Digestive System Flashcards
C-9- Exam 2, part 2
These are the parts of the small intestine and descriptions of them (lecture)
Duodenum-first portion•Receives and neutralizes chyme•Entry for bile ducts (liver, gallbladder) and pancreatic ducts•Digestion takes places and finishes hereJejunum-middle portion•Villi for absorptionIleum-last portion•Less villi than jejunum, has lymphoid tissue•Absorptionfinishes up here though most is done in jejunum
What are nutrients?
To understand weight and nutrition, we first have to understand nutrientsNutrientsare components of food that are needed to perform physiological body functions.Nutrients include:◦carbohydrates◦proteins◦lipids◦minerals◦vitamins
Reversed
This is a digestive tract organ where teeth chew food, tongue tastes food and pushes food for swallowing.
Mouth
What happens in lactose intolerance?
Figure 9.7 Digestion and absorption of organic nutrients. a. Carbohydrate is digested to glucose, which is actively transported into the cells of intestinal villi. From there, glucose moves into the bloodstream. b. Proteins are digested to amino acids, which are actively transported into the cells of intestinal villi. From there, amino acids move into the bloodstream. c. Fats are emulsified by bile and digested to monoglycerides (glycerol) and fatty acids. These diffuse into cells, where they recombine and join with proteins. These lipoproteins, called chylomicrons, enter a lacteal.
a protein/steroid produced by a cell that effects the function of a different target cell.
I am a hormone.
Endocrine functions:
Hormones released into bloodstream
Insulin
Decreases blood sugar levels
Glucagon
Increases blood sugar levels
Exocrine functions:
Pancreatic juice released into duodenum
Contains sodium bicarbonate to neutralize stomach acid
Contains digestive enzymes
Pancreatic amylase digests starches
Trypsin digests proteins
Lipase digests fats
These are the endochrine functions and exochrine functions of the pancreas
When the blood glucose level rises rapidly, the pancreas produces an overload of insulin to bring the level under control and back to homeostasis. Type 1 diabetes occurs when the pancreas does not manufacture sufficient amounts of insulin. This condition is normally diagnosed in childhood. Type 2 diabetes occurs when the pancreas does not make enough insulin or when the body’s cells have become insulin-resistant. Type 2 diabetes normally occurs in adulthood with risk factors such as obesity, inactivity, and a family history of the disease (see Section 16.5).
Diabetes
What is the liver?
This organ contains over 100,000 lobules
Reversed
What are the liver, gallbladder and pancreas.
Liver: produces bile for emulsification of fats; major metabolic organ; processes and stores nutrients
Gallbladder: stores bile from liver & sends to small intestines
Pancreas: produces pancreatic juice, contains digestive enzymes, and sends to small intestines, produces insulin and secretes it into blood after eating
These are the accessory organs of the digestive tract and this is what they do.
Look at illustration 9.6
Reversed
It is the process of moves the food through the esophagus. The contractions continue in the stomach and intestines. Page 172The esophagus plays no role in the chemical digestion of food. Its sole purpose is to move the food bolus from the mouth to the stomach. A constriction called thelower gastroesophageal sphincter marks the entrance of the esophagus to t he stomach. Sphincters are muscles that encircle tubes and act as valves. The tubes close when the sphincters contract, and they open when the sphincters relax. When food or saliva is swallowed, the sphincter relaxes for a moment to allow the food or saliva to enter the stomach (Fig. 9.4b). The sphincter then contracts, preventing the acidic stomach contents from backing up into the esophagus.
When the lower esophageal sphincter fails to open and allow food into the stomach, or when the sphincter is opened and food moves from the stomach back to the esophagus, heartburn occurs. As discussed in the Health feature “Heartburn (GERD)” in Section 9.3, this condition can lead to damage of the esophagus and lower esophageal sphincter. Vomiting occurs when strong contractions of the abdominal muscles and the diaphragm (the muscle separating the thoracic and abdominal cavities) force the contents of the stomach into the esophagus and oral cavity.
What is peristalsis and how does it work?
Where does peristalsis take place?
Does the esophagus play a role in chemical digestion of food?
What are sphincters and which one is at the entrance to the esophagus?
What is Gerd and what are the symptoms?
Reversed
It can be mechanical or chemical, breaking food down into subunits
This is the definition of Digestion.
Fish-shaped spongy organ behind the stomachFunctions of the pancreas1. Produces and secretes a wide spectrum of digestive enzymes into the duodenum of small intestineTrypsin digests proteinsLipasedigests fatsPancreatic amylase digests carbohydrates2. Secretes bicarbonateinto the small intestine to neutralize stomach acids3. Secretes insulininto the blood to keep blood sugar levels under control9.4 The Accessory Organs and Regulation of Secretions
•Alkaline fluid introduced with enzymes neutralizes acidic chyme•Cells of the small intestine release hormones when food enters the small intestine which stimulates the pancreas to secrete pancreatic juice•Endocrine products of pancreas•Insulin-signals uptake of glucose from bloodstream•Glucagon-signals liver to break down glycogen stored there into glucose
Pancreas- lecture notes
Reversed
The stomach wall 4 layers- its own version:
What are two functions of HCL?
What is pepsin?
4 layers
2 modified for specific fxns
muscularis: 3 layers of smooth muscle- circular, longitudinal, & smooth muscle layer- oblique to the other 2 – allowing stretching & mechanical digestion into fragments mixed w/ gastric juice
mucosa- deep folds called rugae- disappear when 1 L full; millions gastric pits–> gastric glands –> gastric juice (pepsin- digests protein + HCL [ph 2, very acidic, killing bacteria, breaks down connective tissue of meat & activates pepsin) + mucus)
Reversed
This is where the organs of the digestive system are found.
GI tract
The pancreas produces insulin to counteract blood glucose levels rising too high– when there is a failure to produce insulin, diabetes happens
the pancrease fails to produce adequate amounts of insulin
How does Type 1 Diabetes occur?
Figure 9.4 The process of swallowing. a. When food is swallowed, the tongue pushes a bolus of food up against the soft palate (left). Then, the soft palate closes off the nasal cavities, and the epiglottis closes off the larynx, so the bolus of food enters the esophagus (right). b. Peristalsis moves food through the esophagus and through a sphincter into the stomach.
Swallowing- Now it’s time to review the diagram in the book in 9.2 on swallowing
Reversed
Time to check out the Anatomy of a Tooth slide :)
Well…. go!
Why is the small intestine named as such?
Bc of its small diameter as compared to the large intestine.
What is the pancreas?
located in back of abdomen behind the stomach
secretes enzymatic juices that aid in digestion
secretes insulin
These are 3 functions of the stomach:
1) stores food 2) begins protein digestion process 3) controls movement of food into small intestine
Reversed
What is the anatomy of the stomach?
Located on the left side of the abdominal cavity•J or C-shaped pouch•Food enters at the cardioesophageal sphincter•Food empties into the small intestine at the pyloric sphincter
Functions to store food, start digestion of proteinsand controls movement of chyme(partially digested foodthickliquid)into the small intestineThere are 3layers of muscle in the muscularislayer of the stomach wall helping in mechanical digestion (churning) and allowing it to stretchThe mucosa layer has deep folds called rugaeand gastric pits that lead into gastric glands that secrete gastric juice
Gastric juice secreted by the gastric glands contains pepsin, an enzyme that breaks down proteins, and hydrochloric acid (HCl) and mucusHClgives the stomach a pH of 2 which activates pepsin and helps kill bacteria found in food, breaks down connective tissue in meatA bacterium, Helicobacter pylori, lives in the mucus and can cause gastric ulcers–they survive exposure to gastric juice (remember this bacterium from Ch. 1 scientific method example?)The stomach empties chymeinto the small intestine after 2-6 hrs.
We are the accessory organs.
Pancreas, Liver, Gallbladder.
Reversed
GI tract
This is where the organs of the digestive system are found.
The pancreas is a fish-shaped, spongy, grayish-pink organ that stretches across the back of the abdomen behind the stomach. Most pancreatic cells produce pancreatic juice, which enters the duodenum via the pancreatic duct (Fig. 9.8a). Pancreatic juice contains sodium bicarbonate (NaHCO3) and digestive enzymes for all types of nutrients. Sodium bicarbonate neutralizes acid chyme from the stomach. Pancreatic amylase digests starch, trypsin digests protein, and pancreatic lipase digests fat.
Tell me about the pancreas.
Reversed
Check out the stomach!
Figure 9.5 The layers of the stomach. a. Structure of the stomach showing the three layers of the muscularis and the folds called rugae. b, c. Gastric glands present in the mucosa secrete mucus, HCI, and pepsin, an enzyme that digests protein. d. Contractions of the stomach control the secretion of chyme into the small intestine at the pyloric sphincter.
Reversed
This is the purpose of digestion.
To hydrolyze or break down macromolecules to subunits- polymers to monomers.
Reversed
Heartburn!
This occurs when acids from the stomach pass into the esophagus (acid reflux). There is a burning sensation in the esophagus. Chronic heartburn is called gastroesophageal reflux disease (GERD).
Regulation of digestive secretions: hormones released by the duodenum of small intestine
Secretin◦Release is stimulated by acid in food and gastric juice ◦Stimulates release of pancreatic juiceCholecystokinin (CCK)◦Partially digested proteins and fats stimulate release of CCK◦Stimulates release of pancreatic juice◦Stimulates production of bile in liver and release of bile from gallbladder
Reversed
About a tooth- nitty gritty–
Figure 9.3 Structures of the mouth. a. The chisel-shaped incisors bite; the pointed canines tear; the fairly flat premolars grind; and the flattened molars crush food. b. Longitudinal section of a tooth. The crown is the portion that projects above the gum line and can be replaced by a dentist if damaged. When a “root canal” is done, the nerves are removed. When the periodontal membrane is inflamed, the teeth can loosen.
What happens when a person has eaten a meal particularly rich in protein.
Gastrin. the stomach produces the hormone gastrin. Gastrin enters the bloodstream, and soon the secretory activity of gastric glands increases.
Classes of Nutrients
A nutrient can be defined as a required component of food that performs a physiological function in the body. Nutrients provide us with energy, promote growth and development, and regulate cellular metabolism.
Carbohydrates
Carbohydrates are either simple or complex (see Section 2.4). Glucose is a simple sugar preferred by the body as an energy source. Complex carbohydrates, consisting of multiple sugar units, are digested to glucose. Although body cells can use fatty acids as an energy source, brain cells require glucose.
Any product made from refined grains, such as white bread, cake, and cookies, should be minimized in the diet. During refinement, fiber is removed from the grains, along with vitamins and minerals, in order for the final product to be mainly starch. In contrast, sources of complex carbohydrates, such as beans, peas, nuts, fruits, and whole-grain products, are recommended as good sources of vitamins, minerals, and fiber (Fig. 9.12). Insoluble fiber adds bulk to fecal material and stimulates movements of the large intestine, preventing constipation. Soluble fiber combines with bile salts and cholesterol in the small intestine and prevents them from being absorbed.
Figure 9.12 Foods rich in fiber. Plants provide a good source of fiber in the diet. They also are a good source of vitamins and minerals when they are not processed (refined).
©Cole Group/Getty Images
These are classes of nutrients
Reversed
This is the definition of Digestion.
It can be mechanical or chemical, breaking food down into subunits
The stomach is ____________with the esophagus above and duodenum below.
continuous
Figure 9.7 Digestion and absorption of organic nutrients. a. Carbohydrate is digested to glucose, which is actively transported into the cells of intestinal villi. From there, glucose moves into the bloodstream. b. Proteins are digested to amino acids, which are actively transported into the cells of intestinal villi. From there, amino acids move into the bloodstream. c. Fats are emulsified by bile and digested to monoglycerides (glycerol) and fatty acids. These diffuse into cells, where they recombine and join with proteins. These lipoproteins, called chylomicrons, enter a lacteal.
Check out diagram 9.7!
What are the major digestive enzymes, where are they found, and what do they digest? What is their breakdown (See and study 9.2 chart well)
Salivary amylase- produced by salivary glands- in mouth- ph is neutral, starch H20 & Maltose
Reversed
Mouth lecture notes
** Carb digestion begins in the mouth **
3 pairs of salivary glands secrete salivary amylase that begins carbohydrate digestion. (so carb digestion starts in the mouth!) Tonsils at the back of the mouth are lymphatic tissues, important in fighting disease. The mouth contains teeth that begin the mechanical breakdown of food. The tongue is covered in taste buds and also assists in the mechanical breakdown and movement of food. The tongue forms a bolus (mass of chewed food) and moves it toward the pharynx. Uvula – Prevents food and drink from entering nasal cavities when swallowing
What is glucose? What is actively transported and villi? What is a blood stream?
Carbohydrates digest into this and it is ______ _________ into cells of intestinal __________. From there, glucose moves into ________
Small intestineDigestion•Enzymes from intestinal cells and pancreas mixed with chyme•Bile enters from liver and gallbladder•Carbohydrate digestion finishes (started in mouth)•Protein digestion finishes (started in stomach)•Fat digestion finishes (started in very , very small amounts in stomach–most of it takes place here)Absorption•Most absorption here–increased surface area (villi, also microvilli and plicaecirculares), longest part of GI tractImmune•Submucosa has Peyer’spatches (collections of lymphatic tissue)
processing of food and the initiation of the process of digestion for proteins
What is the stomach responsible for in the digestive system?
What process of digestion for macromolecules begins in the stomach?
Select the two hormones that are produced by the cells of the duodenal wall.
secretin
cholecystokinin (CCK)
Disorders of the Colon and Rectum
The large intestine is subject to a number of disorders. Many of these can be prevented or minimized by a proper diet and hygiene.
Diarrhea
Diarrhea is characterized by bowel movements that are loose or watery. The major causes of diarrhea are infection of the lower intestinal tract and nervous stimulation. The intestinal wall becomes irritated, and peristalsis increases when an infection occurs. Water is not absorbed, and the diarrhea that results rids the body of the infectious organisms. In nervous diarrhea, the nervous system stimulates the intestinal wall and diarrhea results. Most people have several occurrences of diarrhea each year without suffering any health consequences. However, prolonged diarrhea can lead to dehydration because of water loss, which can lead to an imbalance of salts in the blood that can affect heart muscle contraction and potentially lead to death.
Constipation
When a person is constipated, the feces are dry and hard, making it difficult for them to be expelled. Diets that lack whole-grain foods, as well as ignoring the urge to defecate, are often the causes of constipation. When feces are not expelled regularly, additional water is absorbed from them. The material becomes drier, harder, and more difficult to eliminate. Adequate water and fiber intake can help regularity of defecation. The frequent use of laxatives is discouraged, because it can result in dependence on their use for normal bowel movements. If, however, it is necessary to take a laxative, the most natural is a bulk laxative. Like fiber, it produces a soft mass of cellulose in the colon. Lubricants such as mineral oil make the colon slippery; saline laxatives such as milk of magnesia act osmotically by preventing water from being absorbed. Some laxatives are irritants that increase peristalsis.
Chronic constipation is associated with the development of hemorrhoids, enlarged and inflamed blood vessels at the anus. Other contributing factors for hemorrhoid development include pregnancy, aging, and anal intercourse.
Diverticulosis
As mentioned previously (see Section 9.1), diverticulosis is the occurrence of little pouches of mucosa where food can collect. The pouches form when the mucosa pushes through weak spots in the muscularis. A frequent site is the last part of the descending colon.
Irritable Bowel Syndrome
Also mentioned previously (see Section 9.1), irritable bowel syndrome (IBS), or spastic colon, is a condition in which the muscularis contracts powerfully but without its normal coordination. The symptoms are abdominal cramps; gas; constipation; and urgent, explosive stools (feces discharge).
Inflammatory Bowel Disease
Inflammatory bowel disease (IBD) is a collective term for a number of inflammatory disorders. Ulcerative colitis and Crohn’s disease are the most common of these. Ulcerative colitis affects the large intestine and rectum and results in diarrhea, rectal bleeding, abdominal cramps, and urgency in defecation. Crohn’s disease is normally isolated to the small intestine but can affect any area of the digestive tract, including the colon and rectum. It is characterized by the breakdown of the lining of the affected area, resulting in ulcers. Ulcers are painful and cause bleeding, because they erode the submucosal layer, where there are nerves and blood vessels. This also results in the inability to absorb nutrients at the affected sites. Symptoms of Crohn’s disease include diarrhea, weight loss, abdominal cramping, anemia, bleeding, and malnutrition
SCIENCE IN YOUR LIFE
What is a fecal transplant?
The balance of bacteria, or microbiota, in the large intestine is important not only for the health of the digestive tract but for the entire individual. The use of antibiotics to control problems with the colon can alter the balance, allowing detrimental species of bacteria to dominate the colon, causing chronic diarrhea.
In a fecal material transplant, bacteria from a healthy individual are delivered to the colon using an enema, endoscopy, or oral pills to reestablish a healthy community of microbiota.
.Page 181
Polyps and Cancer
The colon is subject to the development of polyps, small growths arising from the epithelial lining. Polyps, whether benign or cancerous, can be removed surgically. If colon cancer is detected while still confined to a polyp, the expected outcome is a complete cure. The American Cancer Society estimates that over 140,000 new cases of colon and rectal (colorectal) cancer are diagnosed per year in the United States. Some investigators believe that dietary fat increases the likelihood of colon cancer, because dietary fat causes an increase in bile secretion. It could be that intestinal bacteria convert bile salts to substances that promote the development of cancer. Fiber in the diet seems to inhibit the development of colon cancer, and regular elimination reduces the time during which the colon wall is exposed to any cancer-promoting agents in feces.
One diagnostic tool for all of these disorders is an endoscopic exam called a colonoscopy. In a colonoscopy, a flexible tube containing a camera is inserted into the GI tract, usually from the anus. The doctor may then examine the length of the colon, as well as take tissue samples (biopsies) for additional tests. However, as discussed in the Health feature “Swallowing a Camera,” this procedure is gradually being replaced by the PillCam, a camera you swallow.
Disorders of the colon and rectumDiarrhea–increased peristalsis and water is not reabsorbed due to either an infection or nervous stimulationConstipation–condition when feces are dry and hard that may be controlled with water and fiberHemorrhoids–enlarged and inflamed blood vessels of the anus due to chronic constipation, pregnancy, aging, and anal intercourse
Disorders of the colon and rectum
These are the vitamins that the liver stores, and the element that it removed from the blood.
The liver is also a storage organ. It removes iron and the vitamins A, D, E, K, and B12 from blood and stores them.
Reversed
gi tract problems: abdominal pain, nausea, vomiting, diahrrea
These are symptoms of celiac disease.
These are functions of the liver
converts amino groups from excess amino acids to urea
stores iron and certain vitamins
produces bile
regulates blood glucose by producing or breaking down glycogen
Incisors- cutting Canines- tearing, piercing Premolarsgrinding Molars- grinding
The different teeth functions and what they are
LipidsLipidsinclude fats, oils, and cholesterol.Saturated fats (usually of animal origin: butter, lard) are usually solid at room temperature, while unsaturated fats are usually liquid at room temperature(example: olive and canola oil.Essential fatty acids are ones that must be ingested; they include linoleic acid and linolenic acid (these can only be found in polyunsaturated oils such as corn and safflower).9.6 Nutrition and Weight Control
see choosing healthy oil slide and see other slides
Can lipids be harmful?CVD is often a result of arteries blocked by plaques/lesions made of cholesterol and saturated fatsLow density lipoproteins (LDL) is the “bad” cholesterol because it carries cholesterol from the liver to the cellsLDL is increased by saturated fats and decreased by unsaturated fatsHigh density lipoproteins (HDL) is the “good” cholesterol because it carries cholesterol to the liver where it is converted to bile saltsTrans-fatty acids are not found in nature◦Made by hydrogenation of unsaturated fatty acids for commercial products and may reduce the ability of cells to clear cholesterol from the bloodstream9.6 Nutrition and Weight Control17
See other slide on cholesterol
Lipids
Reversed
The stomach (Fig. 9.5) is a thick-walled, J-shaped organ that lies on the left side of the body beneath the diaphragm. The stomach is continuous with the esophagus above and the duodenum of the small intestine below. The stomach stores food, initiates the digestion of protein, and controls the movement of food into the small intestine. Nutrients are not absorbed by the stomach. However, it does absorb alcohol, because alcohol is fat soluble and can pass through membranes easily.
What is the shape of the stomach?
Where is it located?
Photo check time- check out the diagram 9.5
T/F- The stomach is on the right side of the body.
What body parts does the stomach connect to?
What are the functions/purposes of the stomach? - Name 3
Are nutrients absorbed by the stomach? Is Alcohol?
Reversed
To hydrolyze or break down macromolecules to subunits- polymers to monomers.
This is the purpose of digestion.
The stomach has a very thin wall.
False
ProteinsProteins are digested into 20 different amino acids which are used to produce cellular proteins. All 20 must be present to be used.Essential amino acids are the 8 amino acids that mustbe attained through diet (our bodies can’t make them). Complete proteins, that have all essential amino acids, are usually derived from animals such as meat and dairy. Non-animal sources of complete proteins are tofu, soymilk, and other processed food from soybeans.
Incomplete proteins are ones that lack at least one essential amino acid (i.e., legumes, nuts, grains, etc.) and need to be combined with another incomplete protein to allow all amino acids to be used in the body.Amino acids cannot be stored in the body, thus small amounts (2 meat servings) need to be ingested on a daily basis.
What about proteins?
What is bile?
This substance emulsifies fat.
Reversed
Swallowing- Now it’s time to review the diagram in the book in 9.2 on swallowing
Figure 9.4 The process of swallowing. a. When food is swallowed, the tongue pushes a bolus of food up against the soft palate (left). Then, the soft palate closes off the nasal cavities, and the epiglottis closes off the larynx, so the bolus of food enters the esophagus (right). b. Peristalsis moves food through the esophagus and through a sphincter into the stomach.
Reversed
What is the stomach responsible for in the digestive system?
What process of digestion for macromolecules begins in the stomach?
processing of food and the initiation of the process of digestion for proteins
How does the liver act as a sewage treatment plant?
It removes poisonous substances from the blood and detoxifies them.
Cells of the duodenal wall produce two other hormones of particular interest—secretin and cholecystokinin (CCK). Secretin release is stimulated by acid, especially the HCl present in chyme. Partially digested proteins and fat stimulate the release of CCK. Soon after these hormones enter the bloodstream, the pancreas increases its output of pancreatic juice. Pancreatic juice buffers the acidic chyme entering the intestine from the stomach and helps digest food. CCK also causes the liver to increase its production of bile and causes the gallbladder to contract and release stored bile. The bile then aids the digestion of fats that stimulated the release of CCK. Figure 9.9 summarizes the actions of gastrin, secretin, and CCK.
These are two hormones produced by cells of the duodenal wall:
Diverticulosis
This is a condition in which portions of the mucosa of any part of the GI tract—but primarily the large intestine—have pushed through the other layers and formed pouches. The pouches can be likened to an inner tube that pokes through weak places in a tire. When food collects in the pouches, they may become infected or inflamed.
Reversed
These are symptoms of celiac disease.
gi tract problems: abdominal pain, nausea, vomiting, diahrrea
Nutrients are not absorbed by the stomach.
True.
mouth, pharynx, and esophagus
These comprise the upper portion of the GI tract
Chyme’s movement is controlled by what?
Stomach
In the stomach, what are the mucosa walls like and what do they do?
The mucosa layer has deep folds called rugaeand gastric pits that lead into gastric glands that secrete gastric juice9.3 The Stomach and Small Intestine
mouth
This is also called the oral cavity.
Reversed
This is where the majority of nutrient processing occurs.
The small intestine.
Reversed
What is the pharynx?
This is a digestive tract organ which is the passageway where food gets swallowed.
The mucosa layer has deep folds called rugaeand gastric pits that lead into gastric glands that secrete gastric juice9.3 The Stomach and Small Intestine
In the stomach, what are the mucosa walls like and what do they do?
Reversed
This is how long the small intestine is.
This are the chief value(s) of the organ
It is also a site of nutrient absorption
This is how far the small intestine extends from this sphincter to the ileocecalvalve which means from the junction between one place to another;
The enzymes secreted by the pancrease into the small intestine digest these three things
Averages 6m (18 ft) in lengthThe body’s major digestive and absorptive organSite of nutrient absorption into the bloodMuscular tube from pyloric sphincter (junction of stomach and small intestine) to ileocecalvalve (junction of small and large intestine)Enzymes secreted by the pancreas into the small intestine digest carbohydrates, proteins, and fats
Well…. go!
Time to check out the Anatomy of a Tooth slide :)
Reversed
What is the small intestine?
Chyme gets mixed here with digestive enzymes for final breakdown, absorbs nutrient molecules into body, secretes digestive hormones into blood.
Where are plasma proteins made?
Liver
What is the pyloric sphyncter?
This is where food empties out after the stomach.
Small intestineDigestion•Enzymes from intestinal cells and pancreas mixed with chyme•Bile enters from liver and gallbladder•Carbohydrate digestion finishes (started in mouth)•Protein digestion finishes (started in stomach)•Fat digestion finishes (started in very , very small amounts in stomach–most of it takes place here)Absorption•Most absorption here–increased surface area (villi, also microvilli and plicaecirculares), longest part of GI tractImmune•Submucosa has Peyer’spatches (collections of lymphatic tissue)
Reversed
This is the second step of digestion. It involves movement of food along the GI tract and this is its purpose.
Movement of food along GI tract to obtain nutrients and eliminate waste
Reversed
What is the stomach?
This is a GI tract organ where acid and digestive enzymes for protein churns, mixing food with secretions, and sends chyme to the small intestines.
How does Type 1 Diabetes occur?
The pancreas produces insulin to counteract blood glucose levels rising too high– when there is a failure to produce insulin, diabetes happens
the pancrease fails to produce adequate amounts of insulin
Reversed
This is a digestive tract organ which is the passageway where food gets swallowed.
What is the pharynx?
What is the mouth?
Both mechanical and chemical digestion begin here.
converts amino groups from excess amino acids to urea
stores iron and certain vitamins
produces bile
regulates blood glucose by producing or breaking down glycogen
These are functions of the liver
These are the three regions of the small intestine.
duodenum, jejunum, ileum
continuous
The stomach is ____________with the esophagus above and duodenum below.
Control of digestive activityMostly controlled by reflexes via the parasympathetic division of the autonomic system (the ‘rest and digest’ division of control by the nervous system)Chemical and mechanical receptors are located in organ walls that trigger reflexesStimuli include:◦Stretch of the organ◦pH of the contents◦Presence of breakdown products9.5 The Large Intestine and Defecation31
Control of digestive activityReflexes include:◦Activation or inhibition of glandular secretions◦Smooth muscle activity
Control of digestive activity
Disorders of the colon and rectumDiverticulosis–occurrence of pouches of mucosa from weak spots in the muscularislayer that can become infected often in the colonIrritable bowel syndrome(IBS) –muscularislayer contracts with power but without its normal coordination that is characterized by chronic diarrhea and abdominal painInflammatory bowel disease/colitis (IBD) –a group of inflammatory disorders such as ulcerative colitis or Crohn’sdiseasePolyps and cancer –small growths found in the epithelial lining that can be benign or cancerous
Need a lot of water to excrete our nitrogen based waste products like ureaAn overabundance of protein can result in dehydration during exercise and sweating.An overabundance of proteins can lead to calcium loss in urine which can lead to kidney stones.Eating red meat may lead to cardiovascular disease, since this protein source is high in saturated fats.9.6 Nutrition and Weight Control
Other disorders of the rectum and colon
The small intestine is abundant in this which helps to digest carbohydrtes, proteins, and fat content in food.
Where are these secreted mostly? How do they get to the small intestine?
Enzymes
Pancreas
This is general nutritional information I can break down later
Proteins
Dietary proteins are digested to amino acids (see Section 2.6), which cells use to synthesize hundreds of cellular proteins. Of the 20 different amino acids, 8 are essential amino acids that must be present in the diet because the body cannot make them, and 2 others are ones the body makes insufficiently. Eggs, milk products, meat, poultry, and most other foods derived from animals contain all 8 essential amino acids and are “complete,” or “high-quality,” protein sources. Legumes (beans and peas) (Fig. 9.13), other types of vegetables, seeds and nuts, and grains also supply us with amino acids. However, each of these alone is an incomplete protein source, because each is deficient in at least 1 of the essential amino acids. Absence of 1 essential amino acid prevents use of the other 19 amino acids. Therefore, vegetarians are counseled to combine two or more incomplete types of plant products to acquire all the essential amino acids. Tofu, soy milk, and other foods made from processed soybeans are complete protein sources. A balanced vegetarian diet is possible with a little knowledge and planning (see the Health Feature “Protein and Vegetarians”).
Figure 9.13 Foods rich in proteins and complex carbohydrates. Beans are a good source of complex carbohydrates and protein. But beans don’t supply all the essential amino acids. To ensure a complete source of protein in the diet, beans should be eaten in combination with a grain, such as rice.
©Birgit Reitz-Hofmann/Getty Images
BIOLOGY TODAY Health
Protein and Vegetarians
There are approximately 22.8 million vegetarians in the United States. Although definitions vary, most abstain from eating red meat, poultry, and fish. About a third of vegetarians are vegans, who avoid all animal products, while less stringent vegetarians may include eggs and/or dairy products as a part of their regular diet. Although vegetarianism is an important part of certain Eastern religions, most American vegetarians cite ethical or health reasons. Ethical concerns may include the treatment of animals raised as food, and/or the effects of animal agriculture on the environment. On the health side, most nutritional research seems to support the benefits of a low-fat, well-balanced vegetarian diet in reducing the incidence of cardiovascular disease, obesity, diabetes, and certain cancers, especially colon and prostate cancer.
Certain health risks are associated with vegetarian diets. Highly restricted vegetarian diets are probably not appropriate for pregnant or lactating women, or for very young children. Vegans, especially, have to be careful to obtain enough iron, vitamin D, vitamin B12, and certain fatty acids. However, most American vegetarians would likely agree that the most common question they are asked about their dietary habits is, “Where do you get your protein?” Many people believe that humans require meat in their diet in order to obtain sufficient protein. Adding to the confusion, in 1971, Frances Moore Lappé published Diet for a Small Planet, which advocated vegetarianism as a more ecologically sustainable diet. That book also introduced the concept of protein complementation, the idea that foods with insufficient levels of one or more essential amino acids needed to be ingested at the same time as foods higher in those amino acids. This idea has influenced American nutritionists for several decades, but in a later edition of her famous book, Lappé noted that with the exception of a few extreme diets, “if people are getting enough calories, they are virtually certain of getting enough protein.”
A position paper published in 2003 by the American Dietetic Association and Dietitians of Canada echoed these ideas, stating that “plant protein can meet requirements when a variety of plant foods is consumed and energy needs are met,” as well as “complementary proteins do not need to be consumed at the same meal.” Because proteins in plant food such as cereals may be harder to digest than animal proteins, vegetarians may need to include a higher percentage of protein in their diet. Beans, nuts, and legumes are particularly good protein sources, and according to the U.S. Food and Drug Administration, soybeans (Fig. 9C) contain complete protein, meaning that like animal protein, soy protein contains sufficient amounts of all essential amino acids for human nutrition. Soy may have other benefits. In October 1999, the FDA gave food manufacturers permission to put labels on products high in soy protein indicating that they may help lower heart disease risk.
Figure 9C Protein sources. For most adults, protein needs can be met by eating vegetables, such as soybeans, that contain high-quality proteins.
©McGraw-Hill Education/Andrew Resek, photographer
Questions to Consider
What are some of the challenges an individual faces when moving toward a meat-free diet?
In general, proteins are not stored by the body in the way that carbohydrates or fats can be stored. Considering this idea, why do you think the idea of complementary proteins became so well established?
A daily supply of essential amino acids is needed because they are not stored in the body, unlike the other amino acids, which can be stored as proteins and metabolized for cells’ needs. However, it does not take very much protein to meet the daily requirement. Two servings of meat a day (one serving is equal in size to a deck of cards) is usually plenty.
Can Proteins Be Harmful?
The liver removes the nitrogen-containing compound from an amino acid. By converting this portion to urea, the liver enables potentially toxic nitrogen to be removed from our bodies. However, large amounts of water are needed to properly excrete urea. Therefore, dehydration may occur if protein consumption is excessive. High-protein diets, especially those rich in animal proteins, can also increase calcium loss in urine. Excretion of calcium may lead to kidney stones and bone loss.
Certain types of meat, especially red meat, are known to be high in saturated fats; other sources of protein, such as chicken, fish, and eggs, are more likely to be low in saturated fats. As you recall from Section 5.7, excessive dietary saturated fat is a risk factor for cardiovascular disease.
Sufficient proteins are needed to supply the essential amino acids. Meat and dairy sources of protein may supply unwanted saturated fat, but vegetable sources do not.
Lipids
Fats, oils, and cholesterol are lipids (see Section 2.5). Saturated fats, which are solids at room temperature, usually have an animal origin. Two well-known exceptions are palm oil and coconut oil, which contain mostly saturated fats and come from the plants mentioned (Fig. 9.14). Butter and fats associated with meats (like the fat on steak and bacon) contain saturated fats.
Figure 9.14 Saturated and unsaturated fatty acids. This graph shows the percentages of saturated and unsaturated fatty acids in select fats and oils.
Oils contain unsaturated fatty acids, which do not promote cardiovascular disease. Corn oil and safflower oil are high in polyunsaturated fatty acids. Polyunsaturated oils are the only type of fat that contains linoleic acid and linolenic acid, two fatty acids the body cannot make. These fatty acids must be supplied by diet, so they are called essential fatty acids.
Olive oil and canola oil contain a larger percentage of monounsaturated fatty acids than other types of cooking oils. Omega-3 fatty acids—with a double bond in the third position—are believed to preserve brain function and protect against heart disease. Flaxseed contains abundant omega-3 fatty acids. Cold-water fish like salmon, sardines, and trout are also an excellent source.Page 186
Can Lipids Be Harmful?
The risk for cardiovascular disease is increased by a diet high in saturated fats and cholesterol. Saturated fats contribute to the formation of lesions associated with atherosclerosis inside the blood vessels. These lesions, called atherosclerotic plaques, limit the flow of blood through these vessels (see Section 5.7). Cholesterol is carried in the blood by the two transport proteins: high-density lipoprotein (HDL) and low-density lipoprotein (LDL). Cholesterol transported by HDL (the “good” lipoprotein) ends up in the liver, where the cholesterol is metabolized. Cholesterol carried by LDL (the “bad” lipoprotein) ends up being deposited in the tissues. Atherosclerotic plaques form when levels of HDL are low and/or when levels of LDL are high. Recommended levels of HDL and LDL can be reestablished by a diet low in saturated fats and cholesterol.
Trans fatty acids (trans fats) arise when unsaturated fatty acids are hydrogenated to produce a solid fat. The function of the plasma membrane receptors that clear cholesterol from the bloodstream may be reduced by trans fats, resulting in a higher blood cholesterol level. Trans fats are found in commercially packaged goods, such as cookies and crackers. Unfortunately, other snacks, such as microwave popcorn, may be sources as well. Be aware that any packaged goods containing partially hydrogenated vegetable oils or shortening contain trans fats. Some margarines used for home cooking or baking incorporate hydrogenated vegetable oil. Commercially fried foods, such as french fries from some fast-food chains, should be strictly limited in a healthy diet. Though tasty, these are often full of trans fats.Page 187
Table 9.5 gives suggestions on how to reduce dietary saturated fat and cholesterol. It is not a good idea to rely on commercially produced low-fat foods. In some products, the fat has been replaced by sugars; in some others, the fat has been replaced by protein.
Table 9.5Reducing Lipids in the Diet
Table Summary: Table lists different ways to reduce saturated fats and trans fats in the diet that span multiple rows.
To Reduce Saturated Fats and Trans Fats in the Diet
Choose poultry, fish, or dry beans and peas as a protein source.
Remove skin from poultry, and trim fat from red meats before cooking; place on a rack, so that fat drains off.
Broil, boil, or bake rather than fry.
Limit your intake of butter, cream, trans fats, shortenings, and tropical oils (coconut and palm oils).
Use herbs and spices to season vegetables instead of butter, margarine, or sauces. Use lemon juice instead of salad dressing.
Drink skim milk instead of whole milk, and use skim milk in cooking and baking.
To Reduce Dietary Cholesterol
Avoid cheese, egg yolks, liver, and certain shellfish (shrimp and lobster). Preferably, eat white fish and poultry.
Substitute egg whites for egg yolks in both cooking and eating.
Include soluble fiber in the diet. Oat bran, oatmeal, beans, corn, and fruits, such as apples, citrus fruits, and cranberries, are high in soluble fiber.
Unsaturated fats such as those in oils do not lead to cardiovascular disease and are preferred. Fats and oils contain many more calories per gram than do carbohydrates and protein.
Minerals
Minerals are divided into major minerals and trace minerals. Major minerals are needed at quantities greater than 100 milligrams (mg) per day. Trace minerals are needed at levels less than 100 mg per day. Table 9.6 lists selected minerals and gives their functions and food sources.
Table 9.6Minerals
Table Summary: Table lists the names of different types of minerals grouped into two categories, on the basis of minimum and maximum quantity, in column 1. The functions and food sources of each type of mineral in both the groups appear in columns 2 and 3. The health concerns related to each mineral are further listed in columns 4 and 5, with deficiency and toxicity as their column headings.
MineralFunctionsFood SourcesHealth Concerns
DeficiencyToxicity
Major (More than 100 mg/Day Needed)
Calcium +(Ca2+)Strong bones and teeth, nerve conduction, muscle contraction, blood clottingDairy products, leafy green vegetablesStunted growth in children, low bone density in adultsKidney stones, interferes with iron and zinc absorption
Phosphorus (PO43−)Bone and soft tissue growth; part of phospholipids, ATP, and nucleic acidsMeat, dairy products, sunflower seeds, food additivesWeakness, confusion, pain in bones and jointsLow blood and bone calcium levels
Potassium +(K+)Nerve conduction, muscle contractionMany fruits and vegetables, branParalysis, irregular heartbeat, eventual deathVomiting, heart attack, death
Sulfur (S2−)Stabilizes protein shape, neutralizes toxic substancesMeat, dairy products, legumesNot likelyIn animals, depresses growth
Sodium +(Na+)Nerve conduction, pH and water balanceTable saltLethargy, muscle cramps, loss of appetiteEdema, high blood pressure
Chloride (Cl−)Water balanceTable saltNot likelyVomiting, dehydration
Magnesium +(Mg2+)Part of various enzymes for nerve and muscle contraction, protein synthesisWhole grains, leafy green vegetablesMuscle spasm, irregular heartbeat, convulsions, confusion, personality changesDiarrhea
Trace (Less than 100 mg/Day Needed)
Zinc +(Zn2+)Protein synthesis, wound healing, fetal development and growth, immune functionMeats, legumes, whole grainsDelayed wound healing, stunted growth, diarrhea, mental lethargyAnemia, diarrhea, vomiting, renal failure, abnormal cholesterol levels
Iron +(Fe2+)Hemoglobin synthesisWhole grains, meats, prune juiceAnemia, physical and mental sluggishnessIron toxicity disease, organ failure, eventual death
Copper +(Cu2+)Hemoglobin synthesisMeat, nuts, legumesAnemia, stunted growth in childrenDamage to internal organs if not excreted
Iodine (I−)Thyroid hormone synthesisIodized table salt, seafoodThyroid deficiencyDepressed thyroid function, anxiety
Selenium (SeO43−)Part of antioxidant enzymeSeafood, meats, eggsVascular collapse, possible cancer developmentHair and fingernail loss, discolored skin
Manganese +(Mn2+)Part of enzymesNuts, legumes, green vegetablesWeakness and confusionConfusion, coma, death
The major minerals are constituents of cells and body fluids and are structural components of tissues. The trace minerals are often part of larger molecules. For example, iron (Fe2+) is present in hemoglobin, and iodine (I−) is a part of hormones produced by the thyroid gland. Zinc (Zn2+), copper (Cu2+), and manganese (Mn2+) are present in enzymes that catalyze a variety of reactions. As research continues, more and more elements are added to the list of trace minerals considered essential. During the past three decades, for example, very small amounts of selenium, molybdenum, chromium, nickel, vanadium, silicon, and even arsenic have been found to be essential to good health. Table 9.6 also provides signs of deficiency and toxicity for the selected minerals.
Occasionally, individuals do not receive enough iron (especially women), calcium, magnesium, or zinc in their diets. Adult females need more iron in their diet than males (8–18 mg compared with 8–11 mg), because they lose hemoglobin each month during menstruation. Stress can bring on a magnesium deficiency, and due to its high-fiber content, a vegetarian diet may make zinc less available to the body. However, a varied and complete diet usually supplies enough of each type of mineral.
Calcium
Calcium (Ca2+) is a major mineral needed for the construction of bones and teeth. It is also necessary for nerve conduction, muscle contraction, and blood clotting. Many people take calcium supplements to prevent or counteract osteoporosis, a degenerative bone disease that afflicts an estimated one-fourth of older men and one-half of older women in the United States. Osteoporosis develops because bone-eating cells called osteoclasts are more active than bone-forming cells called osteoblasts. The bones become porous, and they break easily because they lack sufficient calcium. Recommended calcium intakes vary by age, but in general 1,000 mg a day is recommended for men and women. After age 50 in women, and 70 in men, this increases to 1,200 mg a day. For many people, calcium supplements are needed to obtain these levels.
Osteoporosis
Small-framed Caucasian women with a family history of osteoporosis are at greatest risk of developing the disease. Smoking and drinking more than nine cups of caffeinated drinks daily may also contribute. Vitamin D is an essential companion to calcium in preventing osteoporosis. Other vitamins may also be helpful; for example, magnesium has been found to suppress the cycle that leads to bone loss. In addition to adequate calcium and vitamin intake, exercise helps prevent osteoporosis. Medications are also available that slow bone loss while increasing skeletal mass.
Sodium
Sodium plays a major role in regulating the body’s water balance, as does chloride (Cl−). Sodium plays an important role in the movement of materials across the plasma membrane (see Section 3.3), as well as the conduction of a nerve impulse (see Section 14.1). The recommended amount of sodium intake per day is 1,500 mg, although the average American takes in more than 3,400 mg every day. This Page 188imbalance has caused concern, because sodium in the form of salt intensifies hypertension (high blood pressure). About one-third of the sodium we consume occurs naturally in foods. Another third is added during commercial processing, and we add the last third either during home cooking or at the table in the form of table salt.
Clearly, it is possible to cut down on the amount of sodium in the diet. Table 9.7 gives recommendations for doing so.
Table 9.7Reducing Dietary Sodium
Table Summary: Table lists the different ways to reduce dietary sodium that span multiple rows.
To Reduce Dietary Sodium
Use spices instead of salt to flavor foods.
Add little or no salt to foods at the table, and add only small amounts of salt when you cook.
Eat unsalted crackers, pretzels, potato chips, nuts, and popcorn.
Avoid hot dogs, ham, bacon, luncheon meats, smoked salmon, sardines, and anchovies.
Avoid processed cheese and canned or dehydrated soups.
Avoid brine-soaked foods, such as pickles and olives.
Read nutrition labels to avoid high-salt products.
SCIENCE IN YOUR LIFE
Where does most of the sodium in the diet come from?
Contrary to popular belief, the majority of the sodium in your diet does not come from the salt you put on your food when you are eating. Instead, most of our sodium (over three-quarters!) comes from processed foods and condiments. Sodium is used in these items both to preserve the food or condiment and to make it taste better. But sometimes the amount of sodium is phenomenal. A single teaspoon of soy sauce contains almost 1,000 mg of sodium, and a half-cup of prepared tomato sauce typically has over 400 mg of sodium. Websites such as nutritiondata.self.com can help you track your daily sodium intake.
Vitamins
Vitamins are organic compounds (other than carbohydrate, fat, and protein) that the body uses for metabolic purposes but is unable to produce in adequate quantity. Many vitamins are portions of coenzymes, enzyme helpers. For example, niacin is part of the coenzyme NAD, and riboflavin is part of another dehydrogenase, FAD (see Section 3.6). Coenzymes are needed in only small amounts, because each can be used over and over. Not all vitamins are coenzymes. Vitamin A, for example, is a precursor for the visual pigment that prevents night blindness. If vitamins are lacking in the diet, various symptoms develop. There are 13 vitamins, divided into those that are fat soluble (Table 9.8) and those that are water soluble (Table 9.9). The differences between fat-soluble and water-soluble vitamins have to do with how the compound gets absorbed into the body, how it is transported by the body, its interaction with body tissues, and how it is stored in the cells.
B Vitamins
Table 9.8Fat-Soluble Vitamins
Table Summary: Table lists the names of different types of vitamins in column 1. The functions and food sources of each type of vitamin appear in columns 2 and 3. The health concerns related to each vitamin are further listed in columns 4 and 5, with deficiency and toxicity as their column headings.
VitaminFunctionsFood SourcesHealth Concerns
DeficiencyToxicity
Vitamin AAntioxidant synthesized from beta-carotene; needed for healthy eyes, skin, hair, and mucous membranes and for proper bone growthDeep yellow/orange and leafy, dark green vegetables; fruits; cheese; whole milk; butter; eggsNight blindness, impaired growth of bones and teethHeadache, dizziness, nausea, hair loss, abnormal development of fetus
Vitamin DGroup of steroids needed for development and maintenance of bones and teeth and for absorption of calciumMilk fortified with vitamin D, fish liver oil; also made in the skin when exposed to sunlightRickets, decalcification and weakening of bonesCalcification of soft tissues, diarrhea, possible renal damage
Vitamin EAntioxidant that prevents oxidation of vitamin A and polyunsaturated fatty acidsLeafy green vegetables, fruits, vegetable oils, nuts, whole-grain breads and cerealsUnknownDiarrhea, nausea, headaches, fatigue, muscle weakness
Vitamin KNeeded for synthesis of substances active in clotting of bloodLeafy green vegetables, cabbage, cauliflowerEasy bruising and bleedingCan interfere with anticoagulant medication
Table 9.9Water-Soluble Vitamins
Table Summary: Table lists the names of different types of water-soluble vitamins in column 1. The functions and food sources of each type of water-soluble vitamin appear in columns 2 and 3. The health concerns related to each water-soluble vitamin are further listed in columns 4 and 5, with deficiency and toxicity as their column headings.
VitaminFunctionsFood SourcesHealth Concerns
DeficiencyToxicity
Vitamin CAntioxidant; needed for forming collagen; helps maintain capillaries, bones, and teethCitrus fruits, leafy green vegetables, tomatoes, potatoes, cabbageScurvy, delayed wound healing, infectionsGout, kidney stones, diarrhea, decreased copper
Thiamine (vitamin B1)Part of coenzyme needed for cellular respiration; also promotes activity of the nervous systemWhole-grain cereals, dried beans and peas, sunflower seeds, nutsBeriberi, muscular weakness, enlarged heartCan interfere with absorption of other vitamins
Riboflavin (vitamin B2)Part of coenzymes, such as FAD; aids cellular respiration, including oxidation of protein and fatNuts, dairy products, whole-grain cereals, poultry, leafy green vegetablesDermatitis, blurred vision, growth failureUnknown
Niacin (nicotinic acid)Part of coenzyme NAD; needed for cellular respiration, including oxidation of protein and fatPeanuts, poultry, whole-grain cereals, leafy green vegetables, beansPellagra, diarrhea, mental disordersHigh blood sugar and uric acid, vasodilation, etc.
Folacin (folic acid)Coenzyme needed for production of hemoglobin and formation of DNADark, leafy green vegetables; nuts; beans; whole-grain cerealsMegaloblastic anemia, spina bifidaMay mask B12 deficiency
Vitamin B6Coenzyme needed for synthesis of hormones and hemoglobin; CNS controlWhole-grain cereals, bananas, beans, poultry, nuts, leafy green vegetablesRarely, convulsions, vomiting, seborrhea, muscular weaknessInsomnia, neuropathy
Pantothenic acidPart of coenzyme A needed for oxidation of carbohydrates and fats; aids in the formation of hormones and certain neurotransmittersNuts, beans, dark green vegetables, poultry, fruits, milkRarely, loss of appetite, mental depression, numbnessUnknown
Vitamin B12Complex, cobalt-containing compound; part of the coenzyme needed for synthesis of nucleic acids and myelinDairy products, fish, poultry, eggs, fortified cerealsPernicious anemiaUnknown
BiotinCoenzyme needed for metabolism of amino acids and fatty acidsGenerally in foods, especially eggsSkin rash, nausea, fatigueUnknown
FAD = flavin adenine dinucleotide; NAD = nicotinamide adenine dinucleotide
Page 189
Antioxidants
Over the past several decades, numerous statistical studies have determined that a diet rich in fruits and vegetables can protect against cancer. Cellular metabolism generates free radicals, unstable molecules that carry an extra electron. The most common free radicals in cells are superoxide (O2−) and hydroxide (OH−). To stabilize themselves, free radicals donate an electron to DNA, to proteins (including enzymes), or to lipids, which can be found in plasma membranes. Such donations often damage these cellular molecules and thereby may lead to disruptions of cellular functions, including even cancer.
Page 190Vitamins C, E, and A are believed to defend the body against free radicals and are therefore termed antioxidants. These vitamins are especially abundant in fruits and vegetables. Dietary guidelines suggest we increase our consumption of fruits and vegetables each day. To achieve this goal, think in terms of salad greens, raw or cooked vegetables, dried fruit, and fruit juice, in addition to apples and oranges and other fresh fruits.
Dietary supplements may provide a potential safeguard against cancer and cardiovascular disease. Nutritionists do not think people should take supplements instead of improving their intake of fruits and vegetables. There are many beneficial compounds in these foods that cannot be obtained from a vitamin pill. These compounds enhance one another’s absorption or action and perform independent biological functions.
Vitamin D
Skin cells contain a precursor cholesterol molecule converted to vitamin D after UV exposure. Vitamin D leaves the skin and is modified first in the kidneys and then in the liver until finally it becomes calcitriol. Calcitriol promotes the absorption of calcium by the intestines. When taking a calcium supplement, it is a good idea to get one with added vitamin D. The lack of vitamin D leads to rickets in children. Rickets, characterized by bowing of the legs, is caused by defective mineralization of the skeleton. Most milk is fortified with vitamin D, which helps prevent the occurrence of rickets.
How to Plan Nutritious Meals
Many serious disorders in Americans are linked to a diet that results in excess body fat. Whereas genetics is a factor in being overweight, a person cannot become fat without taking in more food energy (calories) than is needed. People need calories (energy) for their basal metabolism. Basal metabolism is the number of calories a person’s body burns at rest to maintain normal body functions. A person also needs calories for exercise. The less exercise, the fewer calories needed beyond the basal metabolic rate. So the first step in planning a diet is to limit the number of calories to an amount the person will use each day. Let’s say you do all the necessary calculations (beyond the scope of this book). You discover that, as a woman, the maximum number of calories you can take in each day is 2,000. If you’re a man, you can afford 2,500 calories without gaining weight.
The new guidelines developed by the U.S. Department of Agriculture (USDA) are called MyPlate (Fig. 9.15). This graphical representation replaced the older pyramids because most people found the plate graphic easier to interpret. It can be used to help you decide how those calories should be distributed among the foods to eat. MyPlate emphasizes the proportions of each food group that should be consumed daily.
Figure 9.15 The MyPlate dietary recommendations. The U.S. Department of Agriculture (USDA) developed this visual representation of a food plate as a guide to better health. The size differences on the plate for each food group suggest what portion of your meal should consist of each category. The five different colors illustrate that each food category, in correct proportions, is needed each day for good health. See ChooseMyPlate.gov.
Source: USDA, ChooseMyPlate.gov website
In 2015, the U.S. Department of Health and Human Services and the U.S. Department of Agriculture released a new set of dietary guidelines that focuses more on healthy eating patterns than on strict amounts of nutrients. These guidelines are outlined in the Health feature “New Dietary Guidelines.”
BIOLOGY TODAY Health
New Dietary Guidelines
Dietary guidelines are typically revised by the U.S. government every 5 years to reflect changes in nutrition science. The latest guidelines were released in 2015 by the Departments of Agriculture and Health and Human Services. The overall purposes of these guidelines were to:
Promote health.
Prevent chronic (long-term) disease.
Assist people in reaching and maintaining a healthy weight.
The new guidelines focus less on prescribing quantitative levels for nutrients, and more on establishing healthy eating patterns. These patterns include the following foods:
A variety of vegetables, including leafy vegetables, beans, red and yellow vegetables, and starches.
Fruits.
Grains. At least half of all grains should be whole grains.
Fat-free or low-fat dairy products (including soy).
Proteins in the form of seafood, lean meats, poultry, eggs, legumes, nuts, and soy products.
Oils.
To establish these healthy eating patterns, specific recommendations were made to limit certain nutrients that are recognized as raising health concerns:
Consume less than 10 percent of calories per day from added sugar.
Consume less than 10 percent of calories per day from saturated fats.
Consume less than 2,300 milligrams (mg) per day of sodium.
Alcohol should be consumed only in moderation. A maximum of one drink per day for women and up to two drinks per day for men (and only by adults of legal drinking age).
For more information on these guidelines, including the science of how they were determined, visit health.gov/dietaryguidelines/2015/guidelines/.
Questions to Consider
Why do you think quantitative values were removed for many of the nutrients?
Reflect on your diet over the past 24 hours. How does your diet relate to these general guidelines?
Eat a variety of foods. Foods from all food groups should be included in the diet.
Eat more of these foods: fruits, vegetables, whole grains, and fat-free or low-fat milk products. Choose dark green vegetables, orange vegetables, and leafy vegetables. Dry beans and peas are good sources of fiber and a great protein source as well. Limit potatoes and corn. When eating grains, choose whole grains, such as brown rice, oatmeal, and Page 191whole-wheat bread. Choose fruit as a snack or a topping for foods, instead of sugar.
Choose lean meats, such as poultry, and fish high in omega-3 fatty acids, such as salmon, trout, and herring, in moderate-sized portions. Include oils rich in monounsaturated and polyunsaturated fatty acids in the diet.
Eat less of foods high in saturated or trans fats, added sugars, cholesterol, salt, and alcohol.
Be physically active every day. If you need to lose weight, decrease your calorie intake slowly while maintaining an adequate nutrient intake and increasing your physical activity.
Eating Disorders
People with eating disorders are dissatisfied with their body image. Social, cultural, emotional, and biological factors all contribute to the development of an eating disorder. Serious conditions such as obesity, anorexia nervosa, and bulimia nervosa can lead to malnutrition, disability, and death. Regardless of the eating disorder, early recognition and treatment are crucial.
Anorexia nervosa is a severe psychological disorder characterized by an irrational fear of getting fat. Victims refuse to eat enough food to maintain a healthy body weight (Fig. 9.16a). A self-imposed starvation diet is often accompanied by occasional binge eating, followed by purging and extreme physical activity to avoid weight gain. Binges usually include large amounts of high-calorie foods, and purging episodes involve self-induced vomiting and laxative abuse. About 90% of people suffering from anorexia nervosa are young women; an estimated 1 in 200 teenage girls is affected.
Figure 9.16 The characteristics of different eating disorders. a. People with anorexia nervosa have a mistaken body image and think they are fat, even though they are thin. b. Those with bulimia nervosa overeat and then purge their bodies of the food they have eaten. c. People with muscle dysmorphia think their muscles are underdeveloped. They spend hours at the gym and are preoccupied with diet as a way to gain muscle mass.
(a): ©Ted Foxx/Alamy; (b): ©Donna Day/The Image Bank/Getty Images; (c): ©Kevin Dodge/Corbis/Getty Images Plus
Page 192A person with bulimia nervosa binge eats and then purges to avoid gaining weight (Fig. 9.16b). The cyclical binge-purge behavior can occur several times a day. People with bulimia nervosa can be difficult to identify, because their body weights are often normal and they tend to conceal their bingeing and purging practices. Women are more likely than men to develop bulimia; an estimated 4% of young women suffer from this condition.
Other abnormal eating practices include binge-eating disorder and muscle dysmorphia. Many obese people suffer from binge-eating disorder, a condition characterized by episodes of overeating without purging. Stress, anxiety, anger, and depression can trigger food binges. A person suffering from muscle dysmorphia (Fig. 9.16c) thinks his or her body is underdeveloped. Bodybuilding activities and a preoccupation with diet and body form accompany this condition. The person may spend hours in the gym every day, working out on muscle-strengthening equipment. Unlike anorexia nervosa and bulimia, muscle dysmorphia affects more men than women.
CHECK YOUR PROGRESS 9.6
Briefly describe and give an example of each class of nutrients.
Answer
Carbohydrates are simple or complex sugar units used as energy sources. They include products made from refined grains, beans, peas, nuts, fruits, and whole-grain products. Proteins are long chains of amino acids the body breaks down to make other proteins. They are found in meat, eggs, and milk. Lipids are cholesterol or fats and oils that contain either saturated or unsaturated fatty acid chains used for energy storage. Olive oil contains high levels of monounsaturated fat. Minerals are elements needed either in larger quantities (calcium, phosphorus) or trace quantities (zinc, iron). Vitamins are other organic compounds the body cannot synthesize, like vitamins A, D, E, and K.
Discuss why carbohydrates and fats might be the cause of the obesity epidemic today.
Answer
Carbohydrates and fats store lots of energy, they are consumed in excess, and with a sedentary lifestyle are not burned off with exercise but instead stored as fat.
Explain the difference between a vitamin and mineral.
Answer
Vitamins are organic molecules that cannot be synthesized by the body, whereas minerals are chemical elements needed in various amounts by the body.
CONNECTING THE CONCEPTS
For more information on how the body utilizes nutrients, refer to the following discussions:
Section 12.1 explains how vitamin D acts as a hormone that influences bone growth.
Section 15.4 examines the role of vitamin A in vision.
Section 20.2 examines how a diet with adequate levels of vitamins A and C may help prevent cancer.
CONCLUSION
Celiac disease is a serious condition that affects roughly 1 out of every 100 individuals. Unlike gluten sensitivity, which has many of the same symptoms, celiac disease can cause severe damage to the villi and microvilli lining of the small intestine.
As we have seen in this chapter, the small intestine plays a central role in the processing of nutrients. Any condition that damages the villi and microvilli reduces the effectiveness of the small intestine and can result in weight loss, vitamin and mineral deficiencies, and even cancer of the intestines. Currently, the only treatment for celiac disease is a lifelong diet that strictly avoids exposure to the gluten protein.d
Reversed
Movement of food along GI tract to obtain nutrients and eliminate waste
This is the second step of digestion. It involves movement of food along the GI tract and this is its purpose.
Reversed
Time to look at the anatomy of a stomach slide!!
Make sure to really know it!
Reversed
1) Ingestion- when we take in food in our mouth
2) Digestion - breakdown of larger pieces of food into smaller pieces that can be acted upon by digestive enzymes – can either be mechanical or chemical
Mechanical digestion- chewing of the mouth & wavelike contractions of small muscles in stomach
Chemical digestion: digestive enzymes hydrolyze our food’s macromolecules into absorbable subunits.– begins in the mouth, continues in the stomach, and completes in the small intestines
mechanically or chemically breaking down foods into their subunits
Movement– important for tract to fulfill other functions. For example, food must be passed along from one organ to the next, normally by contractions of smooth muscle tissue called peristalsis, and the indigestible remains must be expelled; food must be moved along the GI tract to obtain nutrients from it and eliminate the waste products
Absorption occurs as subunit molecules produced by chemical digestion (i.e., nutrients) cross the wall of the GI tract and enter the cells lining the tract. From there, the nutrients enter the blood for delivery to the cells. movement of nutrients across the GI tract wall to be delivered to cells, transported in blood
Elimination removes molecules that cannot be digested and need to be discharged from the body. The removal of indigestible wastes through the anus is termed defecation. – removal of indigestible molecules ** The purpose of digestion is to hydrolyze or break down the food into basic nutrients in the presence of water to be used in the body**
These are the processes involved in digestion and in order
Common bile duct
This brings bile from the liver to the small intestine.
Reversed
Absorbs water and salt to form feces.
What happens in the large intestines? Is it GI tract organ?
3 pairs of salivary glands secrete salivary amylase that begins carbohydrate digestion. (so carb digestion starts in the mouth!) Tonsils at the back of the mouth are lymphatic tissues, important in fighting disease. The mouth contains teeth that begin the mechanical breakdown of food. The tongue is covered in taste buds and also assists in the mechanical breakdown and movement of food. The tongue forms a bolus (mass of chewed food) and moves it toward the pharynx. Uvula – Prevents food and drink from entering nasal cavities when swallowing
Mouth lecture notes
** Carb digestion begins in the mouth **
4 layers
2 modified for specific fxns
muscularis: 3 layers of smooth muscle- circular, longitudinal, & smooth muscle layer- oblique to the other 2 – allowing stretching & mechanical digestion into fragments mixed w/ gastric juice
mucosa- deep folds called rugae- disappear when 1 L full; millions gastric pits–> gastric glands –> gastric juice (pepsin- digests protein + HCL [ph 2, very acidic, killing bacteria, breaks down connective tissue of meat & activates pepsin) + mucus)
The stomach wall 4 layers- its own version:
What are two functions of HCL?
What is pepsin?
Reversed
What is the rectum?
This is where after the large intestines the body stores and regulates elimination of feces.
Trendy diet programs◦Pritikindiet: high carbohydrate and fiber diet through whole grains and vegetables◦Atkins: low-carbohydrate, and high protein and fat diet◦Zone and South beach diets: low carbohydrate diets that are high in protein and “healthy” fats◦Paleo/Caveman diet: tries to follow diets of humans before agriculture was done, i.e., low/no carbsPrescription drugsAlli-interferes with fat absorption in small intestine
Surgical procedures◦Gastroplasty: stapling or partitioning of a small portion of the stomach◦Gastric bypass: attaching the lower part of the small intestine to the stomach so most of the food bypasses the stomach and small intestine◦Gastric banding: a constriction band is used to reduce stomach size◦Liposuction: removal of fat cells; best used for overweight people that are not obese or morbidly obese9.6 Nutrition and Weight Control
Exercise◦This is important to build in any weight loss regimen, as expenditure of calories over intake of calories is important and easily accomplished with exercise◦A minimum of 10,000 steps should be taken a day for weight maintenance and health◦12,000-15,000 steps should be taken a day to promote weight loss
Magic Bullet Diets
This organ contains over 100,000 lobules
What is the liver?
Reversed
Tell me all about teeth?
What kind of digestion do they participate in?
Mechanical digestion - chew for swallowing;
Teeth: 20 baby teeth- 1st 2 years of life; eventually replaced by 32 adult teeth
The “wisdom teeth,” the third pair of molars, sometimes fail to erupt.
Each tooth: two main divisions: a crown, the portion of the tooth above the gum line, and a root, the portion below the gum line (Fig. 9.3b). The crown has a layer of enamel, an extremely hard outer covering of calcium compounds; dentin, a thick layer of bonelike material; and an inner pulp, which contains the nerves and the blood vessels. Dentin and pulp also make up a portion of the root, which includes periodontal membranes to anchor the tooth into the jawbone.
Tooth decay, called dental caries or cavities, occurs when bacteria within the mouth metabolize sugar. Acids produced during this metabolism erode the teeth. Tooth decay can be painful when it is severe enough to reach the nerves of the inner pulp. Two measures can prevent tooth decay: eating a limited amount of sweets and daily brushing and flossing of teeth. Fluoride treatments, particularly in children, can make the enamel stronger and more resistant to decay. Gum disease, known to be linked to cardiovascular disease, is more apt to occur with aging. Inflammation of the gums, called gingivitis, can spread to the periodontal membrane, which lines the tooth socket. A person then has periodontitis, characterized by a lcoss of bone and loosening of the teeth. Extensive dental work may be required or teeth will be completely lost.
The teeth and tongue and trouble
Mechanical digestion occurs when our teeth chew food into pieces convenient for swallowing. During the first two years of life, the 20 smaller deciduous, or baby, teeth appear. These are eventually replaced by 32 adult teeth (see Fig. 9.3a). The “wisdom teeth,” the third pair of molars, sometimes fail to erupt. If they push on the other teeth and/or cause pain, they can be removed by a dentist or an oral surgeon. Each tooth has two main divisions: a crown, the portion of the tooth above the gum line, and a root, the portion below the gum line (Fig. 9.3b). The crown has a layer of enamel, an extremely hard outer covering of calcium compounds; dentin, a thick layer of bonelike material; and an inner pulp, which contains the nerves and the blood vessels. Dentin and pulp also make up a portion of the root, which includes periodontal membranes to anchor the tooth into the jawbone.
Tooth decay, called dental caries or cavities, occurs when bacteria within the mouth metabolize sugar. Acids produced during this metabolism erode the teeth. Tooth decay can be painful when it is severe enough to reach the nerves of the inner pulp. Two measures can prevent tooth decay: eating a limited amount of sweets and daily brushing and flossing of teeth. Fluoride treatments, particularly in children, can make the enamel stronger and more resistant to decay. Gum disease, known to be linked to cardiovascular disease, is more apt to occur with aging. Inflammation of the gums, called gingivitis, can spread to the periodontal membrane, which lines the tooth socket. A person then has periodontitis, characterized by a lcoss of bone and loosening of the teeth. Extensive dental work may be required or teeth will be completely lost.
The tongue is covered by a mucous membrane, which contains the sensory receptors called taste buds (see Section 15.3). When taste buds are activated by the presence of food, nerve impulses travel by way of nerves to the brain. The tongue is composed of skeletal muscle, and it assists the teeth in carrying out mechanical digestion by moving food around in the mouth. In preparation for swallowing, the tongue forms chewed food into a mass called a bolus, which it pushes toward the pharynx.
What is the pancreas and where is it?
I stretch behind the back of the abdomen behind the stomach.
Reversed
Both the mouth and the nasal passages lead to the pharynx, which is commonly called the throat (see Fig. 9.1). The pharynx opens into both the food passage (esophagus) and the air passage (trachea, or windpipe). These two tubes are parallel to each other, with the trachea in front of the esophagus.
Food is propelled to the esophagus by two muscle layers by alternating contractions (peristalsis) ◦ wave-like movements/rhythmic squeezing down the tract
The pharynx is a cavity between the mouth and esophagus that serves as a passageway for food (and air) ◦ Oropharynx – posterior to oral cavity ◦ Laryngopharynx – below the oropharynx and connected to the esophagus
Swallowing
Swallowing has a voluntary phase; however, once food or drink is pushed back far enough into the pharynx, swallowing becomes a reflex action performed involuntarily. During swallowing, food normally enters the esophagus, a muscular tube that moves food into the stomach, because other possible avenues are blocked. The soft palate moves back to close off the nasal passages, and the trachea moves up under the epiglottis to cover the glottis. The glottis is the opening to the larynx (voice box) and, therefore, the air passage. We do not breathe when we swallow. The up-and-down movement of the Adam’s apple, the front part of the larynx, is easy to observe when a person swallows (Fig. 9.4a). Sometimes, the epiglottis does not cover the glottis fast enough or completely enough and food or liquid can end up in the trachea instead of the esophagus. When this occurs, the muscles around the lungs contract and force a cough that will bring the food back up the trachea and into the pharynx.
How do we swallow food? Voluntary phase ◦ In the beginning, when food is being swallowed from the mouth into the pharynx is a voluntary act.
Esophagus Esophagus is a long, muscular tube that carries food to the stomach Runs from pharynx through diaphragm to stomach Conducts food by peristalsis Passageway for food only (respiratory system branches off after the pharynx)v
What role do the pharynx and esophagus play?
What is the pharynx commonly called?
What passages lead to the pharynx?
What does the pharynx open up to?
What mode of moving the food does the body use in the esophagus?
What are the components of a pharynx and be able to label them on a diagram- what are their functions?
What are the steps of swallowing? Check out the class slide on it -
Is swallowing voluntary or involuntary?
Destroys old red blood cells; excretes bilirubin, a breakdown product of hemoglobin in bile, a liver product
What is the liver?
Reversed
Why does my stomach “growl”?
As you digest food and liquids, you are also moving gas and air through your GI tract. When pockets of gas and air get squeezed by peristalsis in your stomach and small intestine, it makes a noise, or “growl.” So why do you “growl” when your stomach is empty? The process of digestion begins long before you eat. When your stomach is empty, the brain will tell the stomach muscles to begin peristalsis to aid in stimulating hunger. Those muscle contractions around an empty stomach vibrate and echo, causing the “growling” sound.
Why grrrrr?
This substance emulsifies fat.
What is bile?
Located on the left side of the abdominal cavity•J or C-shaped pouch•Food enters at the cardioesophageal sphincter•Food empties into the small intestine at the pyloric sphincter
Functions to store food, start digestion of proteinsand controls movement of chyme(partially digested foodthickliquid)into the small intestineThere are 3layers of muscle in the muscularislayer of the stomach wall helping in mechanical digestion (churning) and allowing it to stretchThe mucosa layer has deep folds called rugaeand gastric pits that lead into gastric glands that secrete gastric juice
Gastric juice secreted by the gastric glands contains pepsin, an enzyme that breaks down proteins, and hydrochloric acid (HCl) and mucusHClgives the stomach a pH of 2 which activates pepsin and helps kill bacteria found in food, breaks down connective tissue in meatA bacterium, Helicobacter pylori, lives in the mucus and can cause gastric ulcers–they survive exposure to gastric juice (remember this bacterium from Ch. 1 scientific method example?)The stomach empties chymeinto the small intestine after 2-6 hrs.
What is the anatomy of the stomach?
How are Nutrients absorbed in small intestine?
The wall of the small intestine absorbs the sugar, amino acid, glycerol, and fatty acid molecules that were the products of the digestive process. The mucosa of the small intestine is modified for absorption. The mucosa of the small intestine contains fingerlike projections called villi (sing., villus), which give the intestinal wall a soft, velvety appearance (Fig. 9.6). A villus has an outer layer of columnar epithelial cells, and each of these cells has thousands of microscopic extensions called microvilli. Collectively, in electron micrographs, microvilli give the villi a fuzzy border known as the brush border. The microvilli contain enzymes, called brush border enzymes, that complete the digestive process. The microvilli greatly increase the surface area of the villus for the absorption of nutrients. The surface area of the small intestine has been estimated to be approximately that of a tennis court.
Reversed
This is a purpose of digestion.
Hydrolyze/break down food
Look at illustration 9.6
Reversed
This is the passageway where peristalsis pushes food to the stomach. It is a GI tract organ.
What is the esophagus?
What role do the pharynx and esophagus play?
What is the pharynx commonly called?
What passages lead to the pharynx?
What does the pharynx open up to?
What mode of moving the food does the body use in the esophagus?
What are the components of a pharynx and be able to label them on a diagram- what are their functions?
What are the steps of swallowing? Check out the class slide on it -
Is swallowing voluntary or involuntary?
Both the mouth and the nasal passages lead to the pharynx, which is commonly called the throat (see Fig. 9.1). The pharynx opens into both the food passage (esophagus) and the air passage (trachea, or windpipe). These two tubes are parallel to each other, with the trachea in front of the esophagus.
Food is propelled to the esophagus by two muscle layers by alternating contractions (peristalsis) ◦ wave-like movements/rhythmic squeezing down the tract
The pharynx is a cavity between the mouth and esophagus that serves as a passageway for food (and air) ◦ Oropharynx – posterior to oral cavity ◦ Laryngopharynx – below the oropharynx and connected to the esophagus
Swallowing
Swallowing has a voluntary phase; however, once food or drink is pushed back far enough into the pharynx, swallowing becomes a reflex action performed involuntarily. During swallowing, food normally enters the esophagus, a muscular tube that moves food into the stomach, because other possible avenues are blocked. The soft palate moves back to close off the nasal passages, and the trachea moves up under the epiglottis to cover the glottis. The glottis is the opening to the larynx (voice box) and, therefore, the air passage. We do not breathe when we swallow. The up-and-down movement of the Adam’s apple, the front part of the larynx, is easy to observe when a person swallows (Fig. 9.4a). Sometimes, the epiglottis does not cover the glottis fast enough or completely enough and food or liquid can end up in the trachea instead of the esophagus. When this occurs, the muscles around the lungs contract and force a cough that will bring the food back up the trachea and into the pharynx.
How do we swallow food? Voluntary phase ◦ In the beginning, when food is being swallowed from the mouth into the pharynx is a voluntary act.
Esophagus Esophagus is a long, muscular tube that carries food to the stomach Runs from pharynx through diaphragm to stomach Conducts food by peristalsis Passageway for food only (respiratory system branches off after the pharynx)v
Can Carbohydrates Be Harmful?
Nutritionists now recognize that the high intake of refined carbohydrates and fructose sweeteners processed from cornstarch is contributing to the increase in obesity in the United States. In addition, these foods are said to have a high glycemic index (GI), because they quickly increase Page 183blood glucose. When the blood glucose level rises rapidly, the pancreas produces an overload of insulin to bring the level under control. Investigators tell us that a chronically high insulin level may lead to insulin resistance, type 2 diabetes, and increased fat deposition. Deposition of fat is associated with coronary heart disease, liver ailments, and several types of cancer.
Table 9.4 gives suggestions on how to reduce your intake of dietary sugars.
Table 9.4Reducing High-Glycemic-Index Carbohydrates
Table Summary: Table lists different ways to reduce dietary sugar that span multiple rows.
To Reduce Dietary Sugar
Eat fewer sweets, such as candy, soft drinks, ice cream, and pastries.
Eat fresh or frozen fruits or fruits canned without heavy syrup. Avoid artificial fruit juices.
Use less sugar—white, brown, or raw—and less honey and syrups.
Avoid sweetened breakfast cereals.
Eat less jelly, jam, and preserves.
When cooking, use spices, such as cinnamon, instead of sugar to flavor foods.
Do not put sugar in tea or coffee.
Avoid processed foods made from refined carbohydrates, such as white bread, rice, and pasta, and limit potato intake.
Carbohydrates are the preferred energy source for the body. The complex carbohydrates in whole grains, beans, nuts, and fruits contain fiber in addition to simple carbohydrates. Complex carbohydrate foods are often a good source of vitamins and minerals.
Page 185
Can carbs be harmful?
What is the pancreas? And what is secreting insulin into the blood.
I am also an endochrine gland in addition to being an accessory organ in the digestive system. This is the reason why.
Reversed
Mouth
This is a digestive tract organ where teeth chew food, tongue tastes food and pushes food for swallowing.
What is lactose intolerant
If I am
bloating
excessive gas
abdominal cramps
then most likely I am
Reversed
an autoimmune response to a protein called gluten that is found in wheat, barley, and rye. In a person with celiac disease, gluten is viewed as a pathogen by the immune system, causing inflammation of the lining of the intestine and loss of specialized structures called villi and microvilli.
This is the cause of Celiac disease
I am a hormone.
a protein/steroid produced by a cell that effects the function of a different target cell.
What is the shape of the stomach?
Where is it located?
Photo check time- check out the diagram 9.5
T/F- The stomach is on the right side of the body.
What body parts does the stomach connect to?
What are the functions/purposes of the stomach? - Name 3
Are nutrients absorbed by the stomach? Is Alcohol?
The stomach (Fig. 9.5) is a thick-walled, J-shaped organ that lies on the left side of the body beneath the diaphragm. The stomach is continuous with the esophagus above and the duodenum of the small intestine below. The stomach stores food, initiates the digestion of protein, and controls the movement of food into the small intestine. Nutrients are not absorbed by the stomach. However, it does absorb alcohol, because alcohol is fat soluble and can pass through membranes easily.
Today, obesity is often defined as having a body mass index (BMI) of 30 or greater. The body mass index uses a person’s height and weight (Fig. 9.11) to calculate a general approximation of his or her percent body fat. BMI can also be calculated by dividing weight in pounds (lb) by height in inches (in.) squared and multiplying by a conversion factor of 703. Using the metric system, the weight in kilograms (kg) is divided by the height in meters (m) squared:
BMI=weight(lb)height2(in.2)×703BMI=weight(kg)height2(m2)
Most people find it is easier to use a table (Table 9.3), figure (Fig. 9.11), or one of the many online calculators.
Table 9.3BMI Values
Table Summary:
ClassificationBMI Values
Healthy18.5–24.9
Overweight25.0–29.9
Obese30.0–39.9
Extremely obese40.0 and higher
Figure 9.11 The body mass index chart. Match your weight with your height, and then determine your body mass index (BMI). Healthy BMI = 18.5 to 24.9; overweight BMI = 25 to 29.9; obese BMI = 30 to 39.9; extremely obese BMI = 40 or more.
Source: U.S. Department of Agriculture, Dietary Guidelines for Americans, 2005.
Your BMI gives you an idea of how much of your weight is due to adipose tissue, commonly known as fat. In general, the taller you are, the more you could weigh without it being due to fat. Using BMI in this way works for most people, especially if they tend to be sedentary. But your BMI number should be used only as a general guide. It does not take into account fitness, bone structure, or gender. For example, a weightlifter’s BMI might fall in the obese range, not because of the amount of body fat but because of increased bone and muscle weight.
How is obesity defined today? How do you calculate your BMI?
This is when acid reflux occurs, a burning sensation results from stomach acids traveling to esophagus; if it becomes chronic it is gastroesophageal reflux disease (GERD).
Heartburn!
Stomach
This organ controls the movement of food into the small intestine.
What goes on in the stomach during digestion? WHat is secreted? What helps kills bacteria?
Gastric juice secreted by the gastric glands contains pepsin, an enzyme that breaks down proteins, and hydrochloric acid (HCl) and mucusHClgives the stomach a pH of 2 which activates pepsin and helps kill bacteria found in food, breaks down connective tissue in meatA bacterium, Helicobacter pylori, lives in the mucus and can cause gastric ulcers–they survive exposure to gastric juice (remember this bacterium from Ch. 1 scientific method example?)The stomach empties chymeinto the small intestine after 2-6 hrs.
Where does food enter the stomach?
At the cardioesophageal sphincter.
MineralsMajor minerals make up components of cells, body fluids, and tissues (i.e., calcium). You need them at quantities more than 100 mg/dayMinor minerals are components of larger molecules (i.e., iron in hemoglobin). You need them less than 100 mg/dayA varied and complete diet usually provides necessary minerals.9.6 Nutrition and Weight Control19
CalciumCalciumis needed to make bone, nerve impulse conduction, and muscle contraction.1,000 mg/day are recommended to keep bones healthy early in life and 1200 mg/day after 50 years of age in females, 70 years of age in males.Vitamin D is needed with calcium to prevent bone loss (osteoporosis).9.6 Nutrition and Weight Control20
SodiumSodium is needed for regulating water balance.500 mg/day is the recommended amount (on average each American takes in 4,000 -4,700 mg/day!).Sodium can increase hypertension in people who already have it.9.6 Nutrition and Weight Control21
Minerals229.6 Nutrition and Weight Control
VitaminsOrganic compounds (not including proteins, fats, or carbohydrates) are used for metabolism but not produced in high enough quantities by the body.Vitamins are often enzyme helpers (coenzymes).There are a total of 13 vitamins in two groups: fat-soluble (A,D,E,K) and water-soluble (everything else other than A,D,E,K)9.6 Nutrition and Weight Control23
Fat-soluble vitamins9.6 Nutrition and Weight Control24
Water-soluble vitamins9.6 Nutrition and Weight Control25
AntioxidantsFree-radicals–unstable molecules that donate an electron to DNA, proteins, and/or fats in plasma membranes (this leads to cellular damage)Antioxidantsare chemicals that decrease the rate of oxidation or transfer of electrons.Vitamin C, E, and A are considered antioxidants because they are thought to defend the body against free radicals The vitamins are common in fruits and vegetables: ingesting it from food are better than supplements9.6 Nutrition and Weight Control26
- 6 Nutrition and Weight ControlFood label animationBelow is a great explanation of a food label. This was also in Ch. 2 as well, but it fits in nicely here as well!You must be connected to the internet to view this animation and click on the link!http://www.viddler.com/embed/da38cdeb27
- 6 Nutrition and Weight ControlHow to plan nutritious mealsYou do need to consume calories to run your body right!Basal metabolism = number of calories you burn at rest to maintain normal body functionsThe U.S. Department of Agriculture (USDA) has guidelines of the proportions of nutrients you need called “choosemyplate.gov”◦Eat a variety of foods◦Eat more of fruits and veggies, whole grains. fat-free or low-fat milk28
- 6 Nutrition and Weight ControlChoosemyplate.gov29Copyright © McGraw-Hill Education. Permission required for reproduction or display.FruitsGrains ProteinVegetables Dairy ChooseMyPlate.gov
Supplments and nutritional info
A. Liver
B. Gallbladder
C. Pancreas
Reversed
Learn this diagram for structures of the mouth. Also about the teeth:
Teeth Role is mastication (chewing) There are 32 teeth in adults (20 deciduous teeth in babies). ◦ Replacement of deciduous teeth begins between the ages of 6 to 12 Each tooth is made of a crown and a root. A hard covering of enamel and dentin covers the crown.
What is the anatomy of a tongue? What is it composed of? Does it perform mechanical or chemical digestion? What is the mass of food called? Where does it go after it is swallowed?
covered by a mucous membrane, which contains the sensory receptors called taste buds (see Section 15.3). When taste buds are activated by the presence of food, nerve impulses travel by way of nerves to the brain. The tongue is composed of skeletal muscle, and it assists the teeth in carrying out mechanical digestion by moving food around in the mouth. In preparation for swallowing, the tongue forms chewed food into a mass called a bolus, which it pushes toward the pharynx.
The small intestine.
This is where the majority of nutrient processing occurs.
The stomach is beanth this.
What is a diaphragm?
Reversed
How does heartburn happen?
What happens and where does it take place?
What is chronic heart burn called?
This occurs when acids from the stomach pass into the esophagus (acid reflux). There is a burning sensation in the esophagus. Chronic heartburn is called gastroesophageal reflux disease (GERD).
Reversed
The liver is a major organ of the digestive tract.
False
Reversed
Chyme gets mixed here with digestive enzymes for final breakdown, absorbs nutrient molecules into body, secretes digestive hormones into blood.
What is the small intestine?
This vein brings blood to the liver from the GI tract capillary bed.
What is the hepatic portal vein? Be able to identify it on a diagram.
largest gland in the body
lies mainly in the upper right section of the abdominal cavity, under the diaphragm
The liver is a major metabolic gland with approximately 100,000 lobules that serve as its structural and functional units (Fig. 9.8b).
The hepatic portal vein (Fig. 9.8b) brings blood to the liver from the GI tract capillary bed.
Capillaries of the lobules filter this blood. In a sense, the liver acts as a sewage treatment plant when it removes poisonous substances from the blood and detoxifies them (Table 9.2).
<strong>Table 9.2Functions of the Liver</strong>
Table Summary:
Destroys old red blood cells; excretes bilirubin, a breakdown product of hemoglobin in bile, a liver product
Detoxifies blood by removing and metabolizing poisonous substances
Stores iron +(Fe2+), the water-soluble vitamin B12, and the fat-soluble vitamins A, D, E, and K
Makes plasma proteins, such as albumins and fibrinogen, from amino acids
Stores glucose as glycogen after a meal; breaks down glycogen to glucose to maintain the glucose concentration of blood between eating periods
Produces urea after breaking down amino acids
Helps regulate blood cholesterol level, converting some to bile salts
These are all the functions of the liver
Reversed
Both mechanical and chemical digestion begin here.
What is the mouth?
Make sure to really know it!
Time to look at the anatomy of a stomach slide!!
Lactose intolerance
If lactase, the enzyme to break down lactose (milk sugar) is absent, lactose cannot be digestedDiarrhea, gas, bloating, abdominal cramps (from bacteria breaking down lactose not our body) after ingesting dairy products
Why grrrrr?
Why does my stomach “growl”?
As you digest food and liquids, you are also moving gas and air through your GI tract. When pockets of gas and air get squeezed by peristalsis in your stomach and small intestine, it makes a noise, or “growl.” So why do you “growl” when your stomach is empty? The process of digestion begins long before you eat. When your stomach is empty, the brain will tell the stomach muscles to begin peristalsis to aid in stimulating hunger. Those muscle contractions around an empty stomach vibrate and echo, causing the “growling” sound.
I stretch behind the back of the abdomen behind the stomach.
What is the pancreas and where is it?
intolerant
People who do not produce the enzyme lactase in their small intestine have the condition called lactose
Reversed
central space that contains food being digested
open area of a hollow organ or vessel
This is a lumen.
The liver is the largest organ in the body.
False.
Teeth Role is mastication (chewing) There are 32 teeth in adults (20 deciduous teeth in babies). ◦ Replacement of deciduous teeth begins between the ages of 6 to 12 Each tooth is made of a crown and a root. A hard covering of enamel and dentin covers the crown.
Learn this diagram for structures of the mouth. Also about the teeth:
Reversed
This is putting food into the mouth and is the first step of the digestive process.
Ingestion
Tell me about the pancreas.
The pancreas is a fish-shaped, spongy, grayish-pink organ that stretches across the back of the abdomen behind the stomach. Most pancreatic cells produce pancreatic juice, which enters the duodenum via the pancreatic duct (Fig. 9.8a). Pancreatic juice contains sodium bicarbonate (NaHCO3) and digestive enzymes for all types of nutrients. Sodium bicarbonate neutralizes acid chyme from the stomach. Pancreatic amylase digests starch, trypsin digests protein, and pancreatic lipase digests fat.
Regulation of digestive secretions- hormones released by duodenum of small intestine
Regulation of digestive secretions: hormones released by the duodenum of small intestineSecretin◦Release is stimulated by acid in food and gastric juice ◦Stimulates release of pancreatic juiceCholecystokinin (CCK)◦Partially digested proteins and fats stimulate release of CCK◦Stimulates release of pancreatic juice◦Stimulates production of bile in liver and release of bile from gallbladder9.3 The Stomach and Small Intestine
The small intestine is actually longer than the large intestine ( 6 meterscompared to 1.5 meter) - True or False
True
The small intestineBileis secreted by the gallbladderinto the small intestine to emulsify (make into smaller pieces) fats, then the small intestine secretes lipasesto digest themDigested food is absorbed through large surface area created by numerous villi (finger-like projections) and microvilli◦Microvilli are the site of brush border enzymesAmino acids and sugars enter the capillaries while fatty acids and glycerol enter the lacteals(small lymph vessels)
What else happens in the small intestine?
What does bile do?
What are the site of brush border enzymes and what are brush border enzymes?
Where do amino acids go?
Where do sugars go?
Where do fatty acids and glycerol enter?
What are lacteals?
The pancreas is also a gland for which system?
What hormone does it secrete and where?
What is a hormone?
How does the pancreas help regulate in homeostasis and what does it regulate?
What is type 1 diabetes?
What about Type 2 diabetes?
The pancreas is also an endocrine gland (see Section 16.1) that secretes the hormone insulin into the blood. A hormone is a protein or steroid produced by a cell that affects the function of a different (target) cell. When the blood glucose level rises rapidly, the pancreas produces an overload of insulin to bring the level under control and back to homeostasis. Type 1 diabetes occurs when the pancreas does not manufacture sufficient amounts of insulin. This condition is normally diagnosed in childhood. Type 2 diabetes occurs when the pancreas does not make enough insulin or when the body’s cells have become insulin-resistant. Type 2 diabetes normally occurs in adulthood with risk factors such as obesity, inactivity, and a family history of the disease (see Section 16.5).
Reversed
water, minerals, vitamins, salts
These help the body function normally, are found in our food, and are carried by blood and absorbed by the digestive system.
This digests starch
What is pancreatic amylase?
If I am
bloating
excessive gas
abdominal cramps
then most likely I am
What is lactose intolerant
Reversed
False
The liver is a major organ of the digestive tract.
Obesity, or being significantly overweight, has become one of the greatest health problems in the United States. According to the Centers for Disease Control and Prevention (CDC), almost 36.5% of adults, and 17% of children, are classified as obese. These statistics are of great concern, because excess body fat is associated with a higher risk for premature death, type 2 diabetes, hypertension, cardiovascular disease, stroke, gallbladder disease, respiratory dysfunction, osteoarthritis, and certain types of cancer.
The Health feature “Searching for the Magic Weight-Loss Bullet” explains the various ways people have tried to keep their weight under control. The conclusion is that achieving or maintaining a healthy weight requires not only eating a variety of healthy foods but also exercising. In other words, to reverse a trend toward obesity, eat fewer calories by making wiser food choices and be more active.
What are the obesity statistics for children and adults?
Reversed
These are the broken down version of macromolecules and in these forms they can cross the plasma membranes using facilitated and active transport.
amino acids, glycerol, fatty acids, monosaccharides,
Eating disordersAnorexia nervosa –psychological disorder due to fear of getting fat; usually results in self-induced starvation, high physical activity, and may include purgingBulimia nervosa –disorder in which people eat large amounts of high-cloriefood (binge-eating) followed by purging to avoid weight gain, often more than once a day9.6 Nutrition and Weight Control30
Eating disordersBinge-eating disorder –obese people are afflicted; overeating is not followed by purging, and this can lead to depression, anger, anxiety, and more bingesMuscle dysmorphia –characterized by people that think their bodies are underdeveloped and are often preoccupied with body-building activities and diet9.6 Nutrition and Weight Control31
Eating disorders are associated with body imageFigure 9.16 The characteristics of different eating disorders.9.6 Nutrition and Weight ControlCopyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.a. Anorexia nervosab. Bulimia nervosac. Muscle dysmorphiaa: © Ted Foxx/Alamy RF; b: © Donna Day/Stone/Getty Images; c: © Corbis RF32
Eating disorders
Averages 6m (18 ft) in lengthThe body’s major digestive and absorptive organSite of nutrient absorption into the bloodMuscular tube from pyloric sphincter (junction of stomach and small intestine) to ileocecalvalve (junction of small and large intestine)Enzymes secreted by the pancreas into the small intestine digest carbohydrates, proteins, and fats
This is how long the small intestine is.
This are the chief value(s) of the organ
It is also a site of nutrient absorption
This is how far the small intestine extends from this sphincter to the ileocecalvalve which means from the junction between one place to another;
The enzymes secreted by the pancrease into the small intestine digest these three things
mouth pharynx esophagus stomach small intestine large intestine rectum anus
This is the pathway that food follows: **
Reversed
carbohydrates, proteins, lipids
These are three nutrient molecules.
What is Celiac disease?
Celiac Disease
Celiac disease is the result of an autoimmune response (see Section 7.5) against a protein called gluten. Gluten is naturally found in grains such as wheat, barley, and rye. In a person with celiac disease, the presence of gluten in the small intestine results in an inflammatory response, which damages the villi and microvilli of the small intestine. This can lead to a number of medical conditions, including abdominal pain, diarrhea, and malnutrition.
There is a difference between celiac disease and gluten sensitivity. Individuals with gluten sensitivity have some of the same symptoms, but there is no damage to the intestines.
Individuals who have celiac disease are placed on a strict gluten-free diet. Many gluten-free foods can be found in grocery stores, but people who have not been diagnosed with celiac disease or gluten sensitivity will not benefit from a gluten-free diet.
Reversed
This separates the nasal cavity from the oral cavity
roof of the mouth
Muscular sac under liverStores and concentrates bile from the liver Bile is introduced into the duodenum in the presence of fatty foodThe hormone cholecystokinin from small intestine also regulates gall bladder: causes it to contract and release bile
Gallbladder
Reversed
Ingestion
This is putting food into the mouth and is the first step of the digestive process.
This occurs when acids from the stomach pass into the esophagus (acid reflux). There is a burning sensation in the esophagus. Chronic heartburn is called gastroesophageal reflux disease (GERD).
Fix my heartburn
What is a villus?
What is a lacteal?
The lymphatic system is an adjunct to what other system?
Where do monosaccharides and amino acids enter ?
Where do monoglycerides and fatty acids go?
Where do lipoprotein droplets, called chylomicrons go? - what are they? Where do they go next?
After all nutrients are absorbed then where do they go?
Nutrients are absorbed into the vessels of a villus (Fig. 9.7). A villus contains blood capillaries and a small lymphatic capillary called a lacteal. As you know, the lymphatic system is an adjunct to the cardiovascular system. Lymphatic vessels carry a fluid called lymph to the cardiovascular veins. Sugars (monosaccharides) and amino acids enter the blood capillaries of a villus. Single molecules of glycerol, called monoglycerides, and fatty acids enter the epithelial cells of the villi. Lipoprotein droplets, called chylomicrons, are formed when monoglycerides and fatty acids are rejoined in the villi epithelia cells. Chylomicrons then enter a lacteal. After nutrients are absorbed, they are eventually carried to all the cells of the body by the bloodstream.
There are 3 layers of muscle in the muscularislayer of the stomach wall helping in mechanical digestion or this, allowing it to stretch
What is churning?
Reversed
This is a condition in which portions of the mucosa of any part of the GI tract—but primarily the large intestine—have pushed through the other layers and formed pouches. The pouches can be likened to an inner tube that pokes through weak places in a tire. When food collects in the pouches, they may become infected or inflamed.
Diverticulosis
Reversed
What is the anus and what does it do?
The anus controls the release of waste from the digestive tract.
fish-shaped, spongy, grayish-pink organ that stretches across the back of the abdomen behind the stomach.
Most pancreatic cells produce pancreatic juice, which enters the duodenum via the pancreatic duct (Fig. 9.8a). Pancreatic juice contains sodium bicarbonate (NaHCO3) and digestive enzymes for all types of nutrients. Sodium bicarbonate neutralizes acid chyme from the stomach. Pancreatic amylase digests starch, trypsin digests protein, and pancreatic lipase digests fat.
What is the shape of the pancreas and where is it found?
What do pancreatic cells produce and how does it reach the s.i.?
How does the pancreas have a role in ph balance?
What digests starch, what digests protein, adn what digests fat?
What is a stomach?
I am located at the left side of the abdomenal cavity.
Reversed
The different teeth functions and what they are
Incisors- cutting Canines- tearing, piercing Premolarsgrinding Molars- grinding
roof of the mouth
This separates the nasal cavity from the oral cavity
Reversed
lumen-
2) The inner layer next to lumen is mucosa. The mucosal layer contains cells that produce and secrete mucus used to protect all the layers of the tract from the digestive enzymes inside the lumen. Glands in the mucosa of the mouth, stomach, and small intestine also release digestive enzymes that act on specific classes of nutrients. Hydrochloric acid, an important component of digestion, is a compound produced by glands in the mucosa of the stomach
innermost layer– faces the lumen (open space) of GI tract ◦ Produces mucus that protects the lining ◦ Produces digestive enzymes
The second layer in the GI wall is called the submucosa. The submucosal layer is a broad band of loose connective tissue that contains blood vessels, lymphatic vessels, and nerves. These are the vessels that will carry the nutrients absorbed by the mucosa. Lymph nodules, called *Peyer patches, are also in the submucosa of the small intestine. Like the tonsils, they help protect us from disease. The submucosa contains blood vessels, so it can be the site of an inflammatory response (see Section 7.2) that leads to inflammatory bowel disease (IBD). Chronic diarrhea, abdominal pain, fever, and weight loss are symptoms of IBD.
Submucosa – next layer (more superficial) of loose connective tissue that has blood vessels, lymphatic vessels, and nerves ◦ Vessels carry nutrients absorbed by mucosa ◦ Peyer’s patches- immune tissue are found here (we discussed this in Ch7)
The third layer is termed the muscularis and contains two layers of smooth muscle. The inner, circular layer encircles the tract. The outer, longitudinal layer lies in the same direction as the tract. The contraction of these muscles, under nervous and hormonal control, accounts for peristalsis and subsequent movement of digested food from the esophagus to the anus. The muscularis can be associated with irritable bowel syndrome (IBS), in which contractions of the wall cause abdominal pain, constipation, and/or diarrhea. The underlying cause of IBS is not known, although some suggest that because this area is under nervous system control, stress may be an underlying cause.
The fourth and outermost layer of the tract is the serosa, which secretes a lubricating fluid. The serosa is a part of the peritoneum, the internal lining of the abdominal cavity.
Submucosa – next layer (more superficial) of loose connective tissue that has blood vessels, lymphatic vessels, and nerves ◦ Vessels carry nutrients absorbed by mucosa ◦ Peyer’s patches- immune tissue are found here (we discussed this in Ch7)
GI tract wall layers (4)
Duodenum-first portion•Receives and neutralizes chyme•Entry for bile ducts (liver, gallbladder) and pancreatic ducts•Digestion takes places and finishes hereJejunum-middle portion•Villi for absorptionIleum-last portion•Less villi than jejunum, has lymphoid tissue•Absorptionfinishes up here though most is done in jejunum
These are the parts of the small intestine and descriptions of them (lecture)
When an individual is grossly overweight and has a body mass index (BMI)≥ 30BMI = (weight in pounds ÷height in inches)2x 703Healthy = 19.5-24.9BMI is a general guide to estimate how much of a person’s weight is due to adipose tissueBut it does nottake into account gender, fitness, or bone structure, so is only a general guide!
Obesity help!
The liveris a large metabolic organ that lies under the diaphragm and is made of 100,000 lobules.Largest gland in the bodyLocated on the right side of the body under the diaphragmConsists of four lobes Connected to the gall bladder via the common hepatic duct
Filters blood from the GI tract thus acting to remove poisons and detoxify the blood◦Produces urea◦Destroys worn out red blood cells◦Produces blood proteinsRemoves iron, vitamins A, D, E, K (fat soluble vitamins) and B12from the blood and stores themHepatic portal circulation-blood from stomach and small intestine carries nutrients and toxins to the liver
Filters blood from the GI tract thus acting to remove poisons and detoxify the blood◦Produces urea◦Destroys worn out red blood cells◦Produces blood proteinsRemoves iron, vitamins A, D, E, K (fat soluble vitamins) and B12from the blood and stores themHepatic portal circulation-blood from stomach and small intestine carries nutrients and toxins to the liver
Filters blood from the GI tract thus acting to remove poisons and detoxify the blood◦Produces urea◦Destroys worn out red blood cells◦Produces blood proteinsRemoves iron, vitamins A, D, E, K (fat soluble vitamins) and B12from the blood and stores themHepatic portal circulation-blood from stomach and small intestine carries nutrients and toxins to the liver
Filters blood from the GI tract thus acting to remove poisons and detoxify the blood◦Produces urea◦Destroys worn out red blood cells◦Produces blood proteinsRemoves iron, vitamins A, D, E, K (fat soluble vitamins) and B12from the blood and stores themHepatic portal circulation-blood from stomach and small intestine carries nutrients and toxins to the liver
Liver lecture notes
Reversed
What happens in the large intestines? Is it GI tract organ?
Absorbs water and salt to form feces.
Secretin◦Release is stimulated by acid in food and gastric juice ◦Stimulates release of pancreatic juiceCholecystokinin (CCK)◦Partially digested proteins and fats stimulate release of CCK◦Stimulates release of pancreatic juice◦Stimulates production of bile in liver and release of bile from gallbladder
Regulation of digestive secretions: hormones released by the duodenum of small intestine
Reversed
These are three nutrient molecules.
carbohydrates, proteins, lipids
Reversed
Small intestine in digestion (cont)
Bileis secreted by the gallbladderinto this organ to emulsify (make into smaller pieces) fats, then this organ secretes lipasesto digest themDigested food is absorbed through large surface area created by numerous villi (finger-like projections) and microvilli◦Microvilli are the site of brush border enzymesAmino acids and sugars enter the capillaries while fatty acids and glycerol enter the lacteals(small lymph vessels)9.3 The Stomach and Small Intestine
Duodenum-first portion•Receives and neutralizes chyme•Entry for bile ducts (liver, gallbladder) and pancreatic ducts•Digestion takes places and finishes hereJejunum-middle portion•Villi for absorptionIleum-last portion•Less villi than jejunum, has lymphoid tissue•Absorptionfinishes up here though most is done in jejunum7
Small intestineDigestion•Enzymes from intestinal cells and pancreas mixed with chyme•Bile enters from liver and gallbladder•Carbohydrate digestion finishes (started in mouth)•Protein digestion finishes (started in stomach)•Fat digestion finishes (started in very , very small amounts in stomach–most of it takes place here)Absorption•Most absorption here–increased surface area (villi, also microvilli and plicaecirculares), longest part of GI tractImmune•Submucosa has Peyer’spatches (collections of lymphatic tissue)
Bc of its small diameter as compared to the large intestine.
Why is the small intestine named as such?
Reversed
This is a GI tract organ where acid and digestive enzymes for protein churns, mixing food with secretions, and sends chyme to the small intestines.
What is the stomach?
Reversed
These are the accessory organs of the digestive tract and this is what they do.
What are the liver, gallbladder and pancreas.
Liver: produces bile for emulsification of fats; major metabolic organ; processes and stores nutrients
Gallbladder: stores bile from liver & sends to small intestines
Pancreas: produces pancreatic juice, contains digestive enzymes, and sends to small intestines, produces insulin and secretes it into blood after eating
Enzymes
Pancreas
The small intestine is abundant in this which helps to digest carbohydrtes, proteins, and fat content in food.
Where are these secreted mostly? How do they get to the small intestine?
How is urea formed?
As amino acids are converted to glucose, the liver combines their amino groups with carbon dioxide to form urea, the usual nitrogenous waste product in humans.
Reversed
These help the body function normally, are found in our food, and are carried by blood and absorbed by the digestive system.
water, minerals, vitamins, salts
Reversed
GI tract wall layers (4)
lumen-
2) The inner layer next to lumen is mucosa. The mucosal layer contains cells that produce and secrete mucus used to protect all the layers of the tract from the digestive enzymes inside the lumen. Glands in the mucosa of the mouth, stomach, and small intestine also release digestive enzymes that act on specific classes of nutrients. Hydrochloric acid, an important component of digestion, is a compound produced by glands in the mucosa of the stomach
innermost layer– faces the lumen (open space) of GI tract ◦ Produces mucus that protects the lining ◦ Produces digestive enzymes
The second layer in the GI wall is called the submucosa. The submucosal layer is a broad band of loose connective tissue that contains blood vessels, lymphatic vessels, and nerves. These are the vessels that will carry the nutrients absorbed by the mucosa. Lymph nodules, called *Peyer patches, are also in the submucosa of the small intestine. Like the tonsils, they help protect us from disease. The submucosa contains blood vessels, so it can be the site of an inflammatory response (see Section 7.2) that leads to inflammatory bowel disease (IBD). Chronic diarrhea, abdominal pain, fever, and weight loss are symptoms of IBD.
Submucosa – next layer (more superficial) of loose connective tissue that has blood vessels, lymphatic vessels, and nerves ◦ Vessels carry nutrients absorbed by mucosa ◦ Peyer’s patches- immune tissue are found here (we discussed this in Ch7)
The third layer is termed the muscularis and contains two layers of smooth muscle. The inner, circular layer encircles the tract. The outer, longitudinal layer lies in the same direction as the tract. The contraction of these muscles, under nervous and hormonal control, accounts for peristalsis and subsequent movement of digested food from the esophagus to the anus. The muscularis can be associated with irritable bowel syndrome (IBS), in which contractions of the wall cause abdominal pain, constipation, and/or diarrhea. The underlying cause of IBS is not known, although some suggest that because this area is under nervous system control, stress may be an underlying cause.
The fourth and outermost layer of the tract is the serosa, which secretes a lubricating fluid. The serosa is a part of the peritoneum, the internal lining of the abdominal cavity.
Submucosa – next layer (more superficial) of loose connective tissue that has blood vessels, lymphatic vessels, and nerves ◦ Vessels carry nutrients absorbed by mucosa ◦ Peyer’s patches- immune tissue are found here (we discussed this in Ch7)
The roof has two parts: an anterior (toward the front) hard palate and a posterior (toward the back) soft palate The hard palate contains several bones, but the soft palate is composed entirely of muscle. The soft palate ends in a finger-shaped projection called the uvula. The tonsils are also in the back of the mouth on either side of the tongue. Tonsils are lymphatic tissue that helps protect us from disease (see Section 7.1). In the nasopharynx, where the nasal cavity opens above the soft palate, there is a single pharyngeal tonsil, commonly called the adenoids.
These are the attributes of the mouth, the root, the soft palate, and the hard palate and what can be found there.
Gastric juice secreted by the gastric glands contains pepsin, an enzyme that breaks down proteins, and hydrochloric acid (HCl) and mucusHClgives the stomach a pH of 2 which activates pepsin and helps kill bacteria found in food, breaks down connective tissue in meatA bacterium, Helicobacter pylori, lives in the mucus and can cause gastric ulcers–they survive exposure to gastric juice (remember this bacterium from Ch. 1 scientific method example?)The stomach empties chymeinto the small intestine after 2-6 hrs.
What goes on in the stomach during digestion? WHat is secreted? What helps kills bacteria?
This brings bile from the liver to the small intestine.
Common bile duct
These are the endochrine functions and exochrine functions of the pancreas
Endocrine functions:
Hormones released into bloodstream
Insulin
Decreases blood sugar levels
Glucagon
Increases blood sugar levels
Exocrine functions:
Pancreatic juice released into duodenum
Contains sodium bicarbonate to neutralize stomach acid
Contains digestive enzymes
Pancreatic amylase digests starches
Trypsin digests proteins
Lipase digests fats
duodenum, jejunum, ileum
These are the three regions of the small intestine.
Incidence has doubled in the US in the last 20 yearsIn the US ~1/3 of adults are obese and it is now prevalent in children and adolescentsIs associated with an increased risk of premature death, Type 2 diabetes, hypertension, cardiovascular disease, stroke, gallbladder disease, respiratory dysfunction, osteoarthritis, and certain cancersObesity tends to increase with an increase in income.
Lecture notes on obesity and why we should be worried about being tubby
False
The stomach has a very thin wall.
How is digestion completed in the small intestine?
What accessory organs are involved in manufacturing which enzymes, and what do they digest?
The small intestine contains a wide range of enzymes to digest the carbohydrate, protein, and fat content of food (Table 9.1). Most of these enzymes are secreted by the pancreas and enter via a duct at the start of the small intestine, also called the duodenum. Another duct brings bile from the liver and gallbladder into the duodenum (see Fig. 9.8). Bile emulsifies fat. Emulsification is a form of mechanical digestion that causes fat droplets to disperse in water. After emulsification, the lipase enzyme, produced by the pancreas, hydrolyzes fats to form glycerol (monoglyceride) and fatty acids. Pancreatic amylase begins the digestion of carbohydrates. An intestinal enzyme completes the digestion of carbohydrates to glucose. Trypsin, a protease enzyme that originates in the pancreas, begins, and then intestinal enzymes finish, the digestion of proteins to amino acids. The intestine has a slightly basic pH, because pancreatic juice contains sodium bicarbonate (NaHCO3), which neutralizes chyme.
The liver helps regulate blood cholesterol levels as well. Some cholesterol is converted to bile salts by the liver. Bile is a solution of bile salts, water, cholesterol, and bicarbonate. It has a yellowish-green color, because it also contains bilirubin, a pigment protein formed during the breakdown of hemoglobin, which is a process also performed by the liver. Bile is stored in the gallbladder, a pear-shaped organ just below the liver, until it is sent via the bile ducts to the duodenum. Gallstones form when liquid stored in the gallbladder hardens into pieces of stonelike material. In the small intestine, bile salts emulsify fat. When fat is emulsified, it breaks up into droplets. The droplets provide a large surface area that can be acted upon by digestive enzymes.
This is another function of the liver related to regulation of blood levels.
The pancreas secretes digestive enzymes directly into the
duodenum
What happens to proteins?
Figure 9.7 Digestion and absorption of organic nutrients. a. Carbohydrate is digested to glucose, which is actively transported into the cells of intestinal villi. From there, glucose moves into the bloodstream. b. Proteins are digested to amino acids, which are actively transported into the cells of intestinal villi. From there, amino acids move into the bloodstream. c. Fats are emulsified by bile and digested to monoglycerides (glycerol) and fatty acids. These diffuse into cells, where they recombine and join with proteins. These lipoproteins, called chylomicrons, enter a lacteal.
Reversed
Three pairs of salivary glands (see Fig. 9.1) secrete saliva by way of ducts to the mouth. One pair of salivary glands lies at the side of the face immediately below and in front of the ears. The ducts of these salivary glands open on the inner surface of the cheek just above the second upper molar. This pair of glands swells when a person has a viral disease called the mumps. The measles, mumps, and rubella (MMR) vaccination you likely had as a child prevents the mumps. Another pair of salivary glands lies beneath the tongue, and still another pair lies beneath the floor of the oral cavity. The ducts from these salivary glands open under the tongue. You can locate the openings if you use your tongue to feel for small flaps on the inside of your cheek and under your tongue. Saliva is a solution of mucus and water. Saliva also contains salivary amylase, an enzyme that begins the chemical digestion of starch, as well as a buffer called bicarbonate and an antimicrobial compound called lysozyme.
How many pairs of salivary glands are there?
Check out the diagram 9.1-
How do the salivary glands secrete saliva?
Where can one find the salivary glands?
What are mumps?
What is saliva comprised of?
What enzyme can be found in it? What is its purpose?
What does bicarbonate do in saliva?
What else is found in saliva?
cecum, the colon, the rectum, and the anal canal (Fig. 9.10). The large intestine is larger in diameter than the small intestine (6.5 cm compared with 2.5 cm), but it is shorter in length (see Fig. 9.1)
The large intestineincludes the cecum, colon, rectum, and anal canal.It is larger in diameter but shorter than the small intestine.Ileocecal valve to anus Cecum–saclike first part of the large intestineAppendix-hangs off of secum and contains lymphatic tissue that sometimes becomes inflamed (appendicitis)
Absorption of waterEliminates indigestible food from the body as fecesDoes not participate in digestion of foodGoblet cells produce mucus to act as a lubricantBacterial flora produce vitamin K and some B vitamins
The cecum is the first portion of the large intestine, joining the end of the small intestine. The cecum usually has a small projection called the vermiform appendix (the term vermiform describes its “wormlike” appearance) (Fig. 9.10). In humans, the appendix is thought to aid in fighting infections. Scientists have recently proposed that the appendix may also contribute to the population of needed bacteria in the large intestine. An inflamed appendix (appendicitis) may be treated using antibiotics or removed surgically. Should the appendix burst, the result can be peritonitis, a life-threatening swelling and infection of the peritoneum.
The colon includes the ascending colon, which goes up the right side of the body to the level of the liver; the transverse colon, which crosses the abdominal cavity just below the liver and the stomach; the descending colon, which passes down the left side of the body; and the sigmoid colon, which enters the rectum, the last 20 cm of the large intestine. The rectum opens at the anus, where defecation, the expulsion of feces, occurs.
Functions of the Large Intestine
The large intestine does not produce any digestive enzymes, and because the majority of nutrients processing occurred in the small intestine, it does not play a major role in the absorption of any nutrients except for some vitamins. The primary function of the large intestine is to absorb water, an important process to prevent dehydration of the body and maintain homeostasis.
The large intestine can absorb vitamins produced by intestinal flora, the bacteria that inhabit the intestine and aid in keeping us healthy. For many years it was believed that Escherichia coli were the major inhabitants of the colon, but culture methods now show that over 99% of the colon bacteria are other types of bacteria. The bacteria in the large intestine break down indigestible material and produce B-complex vitamins and most of the vitamin K needed by our bodies.
The large intestine forms feces. The consistency of normal feces is usually three-fourths water and one-fourth solid wastes. Bacteria, dietary fiber (indigestible remains), and other indigestible Page 180materials make up the solid wastes. Bacterial action on indigestible materials causes the odor of feces and accounts for the presence of gas. Stercobilin, which is a breakdown product of bilirubin (the yellow-orange bile pigment produced from the breakdown of hemoglobin), and oxidized iron cause the brown color of feces.
Defecation, ridding the body of feces, is also a function of the large intestine. Peristalsis occurs infrequently in the large intestine, but when it does, feces are forced into the rectum. Feces collect in the rectum until it is appropriate to defecate. At that time, stretching of the rectal wall initiates nerve impulses to the spinal cord. Shortly thereafter, the rectal muscles contract and the anal sphincters relax. This allows the feces to exit the body through the anus (Fig. 9.10). A person can inhibit defecation by contracting the external anal sphincter made of skeletal muscle. Ridding the body of indigestible remains is another way the digestive system helps maintain homeostasis.
Large intestine
Pancreatic juice carries this as well as other
1) stores food 2) begins protein digestion process 3) controls movement of food into small intestine
These are 3 functions of the stomach:
Figure 9.5 The layers of the stomach. a. Structure of the stomach showing the three layers of the muscularis and the folds called rugae. b, c. Gastric glands present in the mucosa secrete mucus, HCI, and pepsin, an enzyme that digests protein. d. Contractions of the stomach control the secretion of chyme into the small intestine at the pyloric sphincter.
Check out the stomach!
What role does the liver play in homeostasis?
Does the liver release insulin?
The liver is also involved in blood glucose homeostasis. In the presence of insulin, the liver stores glucose as glycogen. When blood glucose becomes low, the liver releases glucose by breaking down Page 178glycogen. If need be, the liver converts glycerol (from fats) and amino acids to glucose molecules.
What is a diaphragm?
The stomach is beanth this.
Mechanical digestion occurs when our teeth chew food into pieces convenient for swallowing. During the first two years of life, the 20 smaller deciduous, or baby, teeth appear. These are eventually replaced by 32 adult teeth (see Fig. 9.3a). The “wisdom teeth,” the third pair of molars, sometimes fail to erupt. If they push on the other teeth and/or cause pain, they can be removed by a dentist or an oral surgeon. Each tooth has two main divisions: a crown, the portion of the tooth above the gum line, and a root, the portion below the gum line (Fig. 9.3b). The crown has a layer of enamel, an extremely hard outer covering of calcium compounds; dentin, a thick layer of bonelike material; and an inner pulp, which contains the nerves and the blood vessels. Dentin and pulp also make up a portion of the root, which includes periodontal membranes to anchor the tooth into the jawbone.
Tooth decay, called dental caries or cavities, occurs when bacteria within the mouth metabolize sugar. Acids produced during this metabolism erode the teeth. Tooth decay can be painful when it is severe enough to reach the nerves of the inner pulp. Two measures can prevent tooth decay: eating a limited amount of sweets and daily brushing and flossing of teeth. Fluoride treatments, particularly in children, can make the enamel stronger and more resistant to decay. Gum disease, known to be linked to cardiovascular disease, is more apt to occur with aging. Inflammation of the gums, called gingivitis, can spread to the periodontal membrane, which lines the tooth socket. A person then has periodontitis, characterized by a lcoss of bone and loosening of the teeth. Extensive dental work may be required or teeth will be completely lost.
The tongue is covered by a mucous membrane, which contains the sensory receptors called taste buds (see Section 15.3). When taste buds are activated by the presence of food, nerve impulses travel by way of nerves to the brain. The tongue is composed of skeletal muscle, and it assists the teeth in carrying out mechanical digestion by moving food around in the mouth. In preparation for swallowing, the tongue forms chewed food into a mass called a bolus, which it pushes toward the pharynx.
The teeth and tongue and trouble
Reversed
What is the esophagus?
This is the passageway where peristalsis pushes food to the stomach. It is a GI tract organ.
True
The small intestine is actually longer than the large intestine ( 6 meterscompared to 1.5 meter) - True or False
The secretion of digestive juices is dictated by this system along with
Nervous system & digestive hormones
Reversed
This is also called the oral cavity.
mouth
located in back of abdomen behind the stomach
secretes enzymatic juices that aid in digestion
secretes insulin
What is the pancreas?
Reversed
This is the pathway that food follows: **
mouth pharynx esophagus stomach small intestine large intestine rectum anus
Hepatitis and cirrhosis are two serious diseases that affect the entire liver and hinder its ability to repair itself.
Therefore, they are life-threatening diseases.
When a person has a liver ailment, bile pigments may leak into the blood, causing jaundice. Jaundice is a yellowish tint to the whites of the eyes and to the skin of light-pigmented persons. Jaundice can result from hepatitis, inflammation of the liver.
Viral hepatitis occurs in several forms. Hepatitis A is usually acquired from sewage-contaminated drinking water and food.
Hepatitis B, which is usually spread by sexual contact, can also be spread by blood transfusions or contaminated needles. The hepatitis B virus is more contagious than the AIDS virus and is spread in the same way. Vaccines are available for hepatitis A and hepatitis B. Hepatitis C is usually acquired by contact with infected blood and can lead to chronic hepatitis, liver cancer, and death. There is not currently a vaccine for hepatitis C.
Cirrhosis is another chronic disease of the liver. First, the organ becomes fatty, and then liver tissue is replaced by inactive, fibrous scar tissue. Cirrhosis of the liver is often seen in alcoholics, due to malnutrition and the excessive amounts of alcohol (a toxin) the liver is forced to break down. Physicians have also observed cirrhosis of the liver in obese people, who are overweight due to a diet high in fatty foods.
The liver has amazing regenerative powers and can recover if the rate of regeneration exceeds the rate of damage. During liver failure, however, there may not be enough time to let the liver heal itself; liver transplantation is usually the preferred treatment. The liver is a vital organ, and its failure leads to death.
These are liver disorders and the story behind them.
Reversed
Hydrolyze/break down food
This is a purpose of digestion.
True.
Nutrients are not absorbed by the stomach.
To store food
What is the primary function of the stomach?
duodenum
The pancreas secretes digestive enzymes directly into the
Reversed
What is the GI tract?
This is where food is digested within its organs. Food follows the pathway of mouth, pharynx, esophagus to stomach, small intestines, large intestines, rectum, anus.
Reversed
The anus controls the release of waste from the digestive tract.
What is the anus and what does it do?
Now, go!
Check out figure 9.8 B!
Reversed
This is where food is digested within its organs. Food follows the pathway of mouth, pharynx, esophagus to stomach, small intestines, large intestines, rectum, anus.
What is the GI tract?
People who do not produce the enzyme lactase in their small intestine have the condition called lactose
intolerant
This is where food empties out after the stomach.
What is the pyloric sphyncter?
The secretions of digestive juices are controlled/regulated by which system along with digestive hormones.
the nervous system and by digestive hormones
When you look at or smell food, the parasympathetic nervous system automatically stimulates gastric secretion.
At the cardioesophageal sphincter.
Where does food enter the stomach?
Upper right section of the abdomenal cavity underneath the diaphragm.
This is where the liver lies and is under.
Averages 6m (18 ft) in lengthThe body’s major digestive and absorptive organSite of nutrient absorption into the bloodMuscular tube from pyloric sphincter (junction of stomach and small intestine) to ileocecalvalve (junction of small and large intestine)Enzymes secreted by the pancreas into the small intestine digest carbohydrates, proteins, and fats
Small intestine
Nervous system & digestive hormones
The secretion of digestive juices is dictated by this system along with
Reversed
These comprise the upper portion of the GI tract
mouth, pharynx, and esophagus
What is the primary function of the stomach?
To store food
What is pancreatic amylase?
This digests starch
Reversed
amino acids, glycerol, fatty acids, monosaccharides,
These are the broken down version of macromolecules and in these forms they can cross the plasma membranes using facilitated and active transport.
A. Liver
B. Gallbladder
C. Pancreas
Reversed
These are the attributes of the mouth, the root, the soft palate, and the hard palate and what can be found there.
The roof has two parts: an anterior (toward the front) hard palate and a posterior (toward the back) soft palate The hard palate contains several bones, but the soft palate is composed entirely of muscle. The soft palate ends in a finger-shaped projection called the uvula. The tonsils are also in the back of the mouth on either side of the tongue. Tonsils are lymphatic tissue that helps protect us from disease (see Section 7.1). In the nasopharynx, where the nasal cavity opens above the soft palate, there is a single pharyngeal tonsil, commonly called the adenoids.
What is churning?
There are 3 layers of muscle in the muscularislayer of the stomach wall helping in mechanical digestion or this, allowing it to stretch
Reversed
This is where after the large intestines the body stores and regulates elimination of feces.
What is the rectum?
What else happens in the small intestine?
What does bile do?
What are the site of brush border enzymes and what are brush border enzymes?
Where do amino acids go?
Where do sugars go?
Where do fatty acids and glycerol enter?
What are lacteals?
The small intestineBileis secreted by the gallbladderinto the small intestine to emulsify (make into smaller pieces) fats, then the small intestine secretes lipasesto digest themDigested food is absorbed through large surface area created by numerous villi (finger-like projections) and microvilli◦Microvilli are the site of brush border enzymesAmino acids and sugars enter the capillaries while fatty acids and glycerol enter the lacteals(small lymph vessels)
Reversed
Normally, the stomach empties in about 2 to 6 hours. When food leaves the stomach, it is a thick, soupy liquid of partially digested food called chyme. Chyme’s entry into the small intestine is regulated, so that small amounts enter at intervals. Peristaltic waves move the chyme toward the pyloric sphincter, which closes and squeezes most of the chyme back, allowing only a small amount to enter the small intestine at one time (Fig. 9.5d).
How long does it take for the stomach to empty?
What is the thick, soupy liquid called?
Is the liquid’s entry into the small intestine regulated? How so?
What is the route the liquid takes in the body and what allows its movement to occur?
True or False.
If false- where are they found and how many?
The lobules are the structural and functional component of the lungs.
Reversed
This is a lumen.
central space that contains food being digested
open area of a hollow organ or vessel
I am also an endochrine gland in addition to being an accessory organ in the digestive system. This is the reason why.
What is the pancreas? And what is secreting insulin into the blood.
Reversed
These are the processes involved in digestion and in order
1) Ingestion- when we take in food in our mouth
2) Digestion - breakdown of larger pieces of food into smaller pieces that can be acted upon by digestive enzymes – can either be mechanical or chemical
Mechanical digestion- chewing of the mouth & wavelike contractions of small muscles in stomach
Chemical digestion: digestive enzymes hydrolyze our food’s macromolecules into absorbable subunits.– begins in the mouth, continues in the stomach, and completes in the small intestines
mechanically or chemically breaking down foods into their subunits
Movement– important for tract to fulfill other functions. For example, food must be passed along from one organ to the next, normally by contractions of smooth muscle tissue called peristalsis, and the indigestible remains must be expelled; food must be moved along the GI tract to obtain nutrients from it and eliminate the waste products
Absorption occurs as subunit molecules produced by chemical digestion (i.e., nutrients) cross the wall of the GI tract and enter the cells lining the tract. From there, the nutrients enter the blood for delivery to the cells. movement of nutrients across the GI tract wall to be delivered to cells, transported in blood
Elimination removes molecules that cannot be digested and need to be discharged from the body. The removal of indigestible wastes through the anus is termed defecation. – removal of indigestible molecules ** The purpose of digestion is to hydrolyze or break down the food into basic nutrients in the presence of water to be used in the body**
How long does it take for the stomach to empty?
What is the thick, soupy liquid called?
Is the liquid’s entry into the small intestine regulated? How so?
What is the route the liquid takes in the body and what allows its movement to occur?
Normally, the stomach empties in about 2 to 6 hours. When food leaves the stomach, it is a thick, soupy liquid of partially digested food called chyme. Chyme’s entry into the small intestine is regulated, so that small amounts enter at intervals. Peristaltic waves move the chyme toward the pyloric sphincter, which closes and squeezes most of the chyme back, allowing only a small amount to enter the small intestine at one time (Fig. 9.5d).
Mechanical digestion - chew for swallowing;
Teeth: 20 baby teeth- 1st 2 years of life; eventually replaced by 32 adult teeth
The “wisdom teeth,” the third pair of molars, sometimes fail to erupt.
Each tooth: two main divisions: a crown, the portion of the tooth above the gum line, and a root, the portion below the gum line (Fig. 9.3b). The crown has a layer of enamel, an extremely hard outer covering of calcium compounds; dentin, a thick layer of bonelike material; and an inner pulp, which contains the nerves and the blood vessels. Dentin and pulp also make up a portion of the root, which includes periodontal membranes to anchor the tooth into the jawbone.
Tooth decay, called dental caries or cavities, occurs when bacteria within the mouth metabolize sugar. Acids produced during this metabolism erode the teeth. Tooth decay can be painful when it is severe enough to reach the nerves of the inner pulp. Two measures can prevent tooth decay: eating a limited amount of sweets and daily brushing and flossing of teeth. Fluoride treatments, particularly in children, can make the enamel stronger and more resistant to decay. Gum disease, known to be linked to cardiovascular disease, is more apt to occur with aging. Inflammation of the gums, called gingivitis, can spread to the periodontal membrane, which lines the tooth socket. A person then has periodontitis, characterized by a lcoss of bone and loosening of the teeth. Extensive dental work may be required or teeth will be completely lost.
Tell me all about teeth?
What kind of digestion do they participate in?
What is the shape of the pancreas and where is it found?
What do pancreatic cells produce and how does it reach the s.i.?
How does the pancreas have a role in ph balance?
What digests starch, what digests protein, adn what digests fat?
fish-shaped, spongy, grayish-pink organ that stretches across the back of the abdomen behind the stomach.
Most pancreatic cells produce pancreatic juice, which enters the duodenum via the pancreatic duct (Fig. 9.8a). Pancreatic juice contains sodium bicarbonate (NaHCO3) and digestive enzymes for all types of nutrients. Sodium bicarbonate neutralizes acid chyme from the stomach. Pancreatic amylase digests starch, trypsin digests protein, and pancreatic lipase digests fat.
CarbohydratesCarbohydrates are sugars or polysaccharides that are digested into the simple sugars which are an important energy source.Refined grains should be minimized in the diet because fiber and vitamins are removed (i.e., white bread, cake, and cookies).Complex carbohydrates are recommended as a good source of vitamins and minerals (i.e., beans, whole-grain products, nuts, and fruits).
Can carbohydrates be harmful?Refined sugars and fructose sweeteners may contribute to obesity; have a high glycemic index (quickly increase blood glucose)These foods may cause the pancreas to secrete large amounts of insulin which can lead to insulin resistance seen in type 2 diabetes and increased resistance to fat metabolism.An increase in fat deposition may increase the risk of coronary heart disease, liver diseases, and certain cancers.
Carbohydrates
What is peristalsis and how does it work?
Where does peristalsis take place?
Does the esophagus play a role in chemical digestion of food?
What are sphincters and which one is at the entrance to the esophagus?
What is Gerd and what are the symptoms?
It is the process of moves the food through the esophagus. The contractions continue in the stomach and intestines. Page 172The esophagus plays no role in the chemical digestion of food. Its sole purpose is to move the food bolus from the mouth to the stomach. A constriction called thelower gastroesophageal sphincter marks the entrance of the esophagus to t he stomach. Sphincters are muscles that encircle tubes and act as valves. The tubes close when the sphincters contract, and they open when the sphincters relax. When food or saliva is swallowed, the sphincter relaxes for a moment to allow the food or saliva to enter the stomach (Fig. 9.4b). The sphincter then contracts, preventing the acidic stomach contents from backing up into the esophagus.
When the lower esophageal sphincter fails to open and allow food into the stomach, or when the sphincter is opened and food moves from the stomach back to the esophagus, heartburn occurs. As discussed in the Health feature “Heartburn (GERD)” in Section 9.3, this condition can lead to damage of the esophagus and lower esophageal sphincter. Vomiting occurs when strong contractions of the abdominal muscles and the diaphragm (the muscle separating the thoracic and abdominal cavities) force the contents of the stomach into the esophagus and oral cavity.
Bile
is secreted by the gallbladder
into this organ to emulsify (make into smaller pieces) fats, then this organ secretes lipase
sto digest themDigested food is absorbed through large surface area created by numerous villi (finger-like projections) and microvilli◦Microvilli are the site of brush border enzymesAmino acids and sugars enter the capillaries while fatty acids and glycerol enter the lacteals(small lymph vessels)
See Figure 9.3
Duodenum-first portion•Receives and neutralizes chyme•Entry for bile ducts (liver, gallbladder) and pancreatic ducts•Digestion takes places and finishes hereJejunum-middle portion•Villi for absorptionIleum-last portion•Less villi than jejunum, has lymphoid tissue•Absorptionfinishes up here though most is done in jejunum7
Small intestineDigestion•Enzymes from intestinal cells and pancreas mixed with chyme•Bile enters from liver and gallbladder•Carbohydrate digestion finishes (started in mouth)•Protein digestion finishes (started in stomach)•Fat digestion finishes (started in very , very small amounts in stomach–most of it takes place here)Absorption•Most absorption here–increased surface area (villi, also microvilli and plicaecirculares), longest part of GI tractImmune•Submucosa has Peyer’spatches (collections of lymphatic tissue)
Small intestine in digestion (cont)
How many pairs of salivary glands are there?
Check out the diagram 9.1-
How do the salivary glands secrete saliva?
Where can one find the salivary glands?
What are mumps?
What is saliva comprised of?
What enzyme can be found in it? What is its purpose?
What does bicarbonate do in saliva?
What else is found in saliva?
Three pairs of salivary glands (see Fig. 9.1) secrete saliva by way of ducts to the mouth. One pair of salivary glands lies at the side of the face immediately below and in front of the ears. The ducts of these salivary glands open on the inner surface of the cheek just above the second upper molar. This pair of glands swells when a person has a viral disease called the mumps. The measles, mumps, and rubella (MMR) vaccination you likely had as a child prevents the mumps. Another pair of salivary glands lies beneath the tongue, and still another pair lies beneath the floor of the oral cavity. The ducts from these salivary glands open under the tongue. You can locate the openings if you use your tongue to feel for small flaps on the inside of your cheek and under your tongue. Saliva is a solution of mucus and water. Saliva also contains salivary amylase, an enzyme that begins the chemical digestion of starch, as well as a buffer called bicarbonate and an antimicrobial compound called lysozyme.
Figure 9.3 Structures of the mouth. a. The chisel-shaped incisors bite; the pointed canines tear; the fairly flat premolars grind; and the flattened molars crush food. b. Longitudinal section of a tooth. The crown is the portion that projects above the gum line and can be replaced by a dentist if damaged. When a “root canal” is done, the nerves are removed. When the periodontal membrane is inflamed, the teeth can loosen.
About a tooth- nitty gritty–
This organ controls the movement of food into the small intestine.
Stomach
Reversed
This is the cause of Celiac disease
an autoimmune response to a protein called gluten that is found in wheat, barley, and rye. In a person with celiac disease, gluten is viewed as a pathogen by the immune system, causing inflammation of the lining of the intestine and loss of specialized structures called villi and microvilli.
Salivary amylase- produced by salivary glands- in mouth- ph is neutral, starch H20 & Maltose
What are the major digestive enzymes, where are they found, and what do they digest? What is their breakdown (See and study 9.2 chart well)
Stomach
Chyme’s movement is controlled by what?
Small intestine
Averages 6m (18 ft) in lengthThe body’s major digestive and absorptive organSite of nutrient absorption into the bloodMuscular tube from pyloric sphincter (junction of stomach and small intestine) to ileocecalvalve (junction of small and large intestine)Enzymes secreted by the pancreas into the small intestine digest carbohydrates, proteins, and fats
I am located at the left side of the abdomenal cavity.
What is a stomach?
secretin
cholecystokinin (CCK)
Select the two hormones that are produced by the cells of the duodenal wall.
Regulation of digestive secretions: hormones released by the duodenum of small intestineSecretin◦Release is stimulated by acid in food and gastric juice ◦Stimulates release of pancreatic juiceCholecystokinin (CCK)◦Partially digested proteins and fats stimulate release of CCK◦Stimulates release of pancreatic juice◦Stimulates production of bile in liver and release of bile from gallbladder9.3 The Stomach and Small Intestine
Regulation of digestive secretions- hormones released by duodenum of small intestine
If lactase, the enzyme to break down lactose (milk sugar) is absent, lactose cannot be digestedDiarrhea, gas, bloating, abdominal cramps (from bacteria breaking down lactose not our body) after ingesting dairy products
Lactose intolerance
The small intestine contains a wide range of enzymes to digest the carbohydrate, protein, and fat content of food (Table 9.1). Most of these enzymes are secreted by the pancreas and enter via a duct at the start of the small intestine, also called the duodenum. Another duct brings bile from the liver and gallbladder into the duodenum (see Fig. 9.8). Bile emulsifies fat. Emulsification is a form of mechanical digestion that causes fat droplets to disperse in water. After emulsification, the lipase enzyme, produced by the pancreas, hydrolyzes fats to form glycerol (monoglyceride) and fatty acids. Pancreatic amylase begins the digestion of carbohydrates. An intestinal enzyme completes the digestion of carbohydrates to glucose. Trypsin, a protease enzyme that originates in the pancreas, begins, and then intestinal enzymes finish, the digestion of proteins to amino acids. The intestine has a slightly basic pH, because pancreatic juice contains sodium bicarbonate (NaHCO3), which neutralizes chyme.
How is digestion completed in the small intestine?
What accessory organs are involved in manufacturing which enzymes, and what do they digest?
The wall of the small intestine absorbs the sugar, amino acid, glycerol, and fatty acid molecules that were the products of the digestive process. The mucosa of the small intestine is modified for absorption. The mucosa of the small intestine contains fingerlike projections called villi (sing., villus), which give the intestinal wall a soft, velvety appearance (Fig. 9.6). A villus has an outer layer of columnar epithelial cells, and each of these cells has thousands of microscopic extensions called microvilli. Collectively, in electron micrographs, microvilli give the villi a fuzzy border known as the brush border. The microvilli contain enzymes, called brush border enzymes, that complete the digestive process. The microvilli greatly increase the surface area of the villus for the absorption of nutrients. The surface area of the small intestine has been estimated to be approximately that of a tennis court.
How are Nutrients absorbed in small intestine?
Nutrients are absorbed into the vessels of a villus (Fig. 9.7). A villus contains blood capillaries and a small lymphatic capillary called a lacteal. As you know, the lymphatic system is an adjunct to the cardiovascular system. Lymphatic vessels carry a fluid called lymph to the cardiovascular veins. Sugars (monosaccharides) and amino acids enter the blood capillaries of a villus. Single molecules of glycerol, called monoglycerides, and fatty acids enter the epithelial cells of the villi. Lipoprotein droplets, called chylomicrons, are formed when monoglycerides and fatty acids are rejoined in the villi epithelia cells. Chylomicrons then enter a lacteal. After nutrients are absorbed, they are eventually carried to all the cells of the body by the bloodstream.
What is a villus?
What is a lacteal?
The lymphatic system is an adjunct to what other system?
Where do monosaccharides and amino acids enter ?
Where do monoglycerides and fatty acids go?
Where do lipoprotein droplets, called chylomicrons go? - what are they? Where do they go next?
After all nutrients are absorbed then where do they go?
Check out diagram 9.7!
Figure 9.7 Digestion and absorption of organic nutrients. a. Carbohydrate is digested to glucose, which is actively transported into the cells of intestinal villi. From there, glucose moves into the bloodstream. b. Proteins are digested to amino acids, which are actively transported into the cells of intestinal villi. From there, amino acids move into the bloodstream. c. Fats are emulsified by bile and digested to monoglycerides (glycerol) and fatty acids. These diffuse into cells, where they recombine and join with proteins. These lipoproteins, called chylomicrons, enter a lacteal.
Carbohydrates digest into this and it is ______ _________ into cells of intestinal __________. From there, glucose moves into ________
What is glucose? What is actively transported and villi? What is a blood stream?
Figure 9.7 Digestion and absorption of organic nutrients. a. Carbohydrate is digested to glucose, which is actively transported into the cells of intestinal villi. From there, glucose moves into the bloodstream. b. Proteins are digested to amino acids, which are actively transported into the cells of intestinal villi. From there, amino acids move into the bloodstream. c. Fats are emulsified by bile and digested to monoglycerides (glycerol) and fatty acids. These diffuse into cells, where they recombine and join with proteins. These lipoproteins, called chylomicrons, enter a lacteal.
What happens to proteins?
Figure 9.7 Digestion and absorption of organic nutrients. a. Carbohydrate is digested to glucose, which is actively transported into the cells of intestinal villi. From there, glucose moves into the bloodstream. b. Proteins are digested to amino acids, which are actively transported into the cells of intestinal villi. From there, amino acids move into the bloodstream. c. Fats are emulsified by bile and digested to monoglycerides (glycerol) and fatty acids. These diffuse into cells, where they recombine and join with proteins. These lipoproteins, called chylomicrons, enter a lacteal.
What happens in lactose intolerance?
Celiac Disease
Celiac disease is the result of an autoimmune response (see Section 7.5) against a protein called gluten. Gluten is naturally found in grains such as wheat, barley, and rye. In a person with celiac disease, the presence of gluten in the small intestine results in an inflammatory response, which damages the villi and microvilli of the small intestine. This can lead to a number of medical conditions, including abdominal pain, diarrhea, and malnutrition.
There is a difference between celiac disease and gluten sensitivity. Individuals with gluten sensitivity have some of the same symptoms, but there is no damage to the intestines.
Individuals who have celiac disease are placed on a strict gluten-free diet. Many gluten-free foods can be found in grocery stores, but people who have not been diagnosed with celiac disease or gluten sensitivity will not benefit from a gluten-free diet.
What is Celiac disease?
covered by a mucous membrane, which contains the sensory receptors called taste buds (see Section 15.3). When taste buds are activated by the presence of food, nerve impulses travel by way of nerves to the brain. The tongue is composed of skeletal muscle, and it assists the teeth in carrying out mechanical digestion by moving food around in the mouth. In preparation for swallowing, the tongue forms chewed food into a mass called a bolus, which it pushes toward the pharynx.
What is the anatomy of a tongue? What is it composed of? Does it perform mechanical or chemical digestion? What is the mass of food called? Where does it go after it is swallowed?
Pancreas, Liver, Gallbladder.
We are the accessory organs.
The pancreas is also an endocrine gland (see Section 16.1) that secretes the hormone insulin into the blood. A hormone is a protein or steroid produced by a cell that affects the function of a different (target) cell. When the blood glucose level rises rapidly, the pancreas produces an overload of insulin to bring the level under control and back to homeostasis. Type 1 diabetes occurs when the pancreas does not manufacture sufficient amounts of insulin. This condition is normally diagnosed in childhood. Type 2 diabetes occurs when the pancreas does not make enough insulin or when the body’s cells have become insulin-resistant. Type 2 diabetes normally occurs in adulthood with risk factors such as obesity, inactivity, and a family history of the disease (see Section 16.5).
The pancreas is also a gland for which system?
What hormone does it secrete and where?
What is a hormone?
How does the pancreas help regulate in homeostasis and what does it regulate?
What is type 1 diabetes?
What about Type 2 diabetes?
These are all the functions of the liver
largest gland in the body
lies mainly in the upper right section of the abdominal cavity, under the diaphragm
The liver is a major metabolic gland with approximately 100,000 lobules that serve as its structural and functional units (Fig. 9.8b).
The hepatic portal vein (Fig. 9.8b) brings blood to the liver from the GI tract capillary bed.
Capillaries of the lobules filter this blood. In a sense, the liver acts as a sewage treatment plant when it removes poisonous substances from the blood and detoxifies them (Table 9.2).
<strong>Table 9.2Functions of the Liver</strong>
Table Summary:
Destroys old red blood cells; excretes bilirubin, a breakdown product of hemoglobin in bile, a liver product
Detoxifies blood by removing and metabolizing poisonous substances
Stores iron +(Fe2+), the water-soluble vitamin B12, and the fat-soluble vitamins A, D, E, and K
Makes plasma proteins, such as albumins and fibrinogen, from amino acids
Stores glucose as glycogen after a meal; breaks down glycogen to glucose to maintain the glucose concentration of blood between eating periods
Produces urea after breaking down amino acids
Helps regulate blood cholesterol level, converting some to bile salts
Pancreas- lecture notes
Fish-shaped spongy organ behind the stomachFunctions of the pancreas1. Produces and secretes a wide spectrum of digestive enzymes into the duodenum of small intestineTrypsin digests proteinsLipasedigests fatsPancreatic amylase digests carbohydrates2. Secretes bicarbonateinto the small intestine to neutralize stomach acids3. Secretes insulininto the blood to keep blood sugar levels under control9.4 The Accessory Organs and Regulation of Secretions
•Alkaline fluid introduced with enzymes neutralizes acidic chyme•Cells of the small intestine release hormones when food enters the small intestine which stimulates the pancreas to secrete pancreatic juice•Endocrine products of pancreas•Insulin-signals uptake of glucose from bloodstream•Glucagon-signals liver to break down glycogen stored there into glucose
Liver lecture notes
The liveris a large metabolic organ that lies under the diaphragm and is made of 100,000 lobules.Largest gland in the bodyLocated on the right side of the body under the diaphragmConsists of four lobes Connected to the gall bladder via the common hepatic duct
Filters blood from the GI tract thus acting to remove poisons and detoxify the blood◦Produces urea◦Destroys worn out red blood cells◦Produces blood proteinsRemoves iron, vitamins A, D, E, K (fat soluble vitamins) and B12from the blood and stores themHepatic portal circulation-blood from stomach and small intestine carries nutrients and toxins to the liver
Filters blood from the GI tract thus acting to remove poisons and detoxify the blood◦Produces urea◦Destroys worn out red blood cells◦Produces blood proteinsRemoves iron, vitamins A, D, E, K (fat soluble vitamins) and B12from the blood and stores themHepatic portal circulation-blood from stomach and small intestine carries nutrients and toxins to the liver
Filters blood from the GI tract thus acting to remove poisons and detoxify the blood◦Produces urea◦Destroys worn out red blood cells◦Produces blood proteinsRemoves iron, vitamins A, D, E, K (fat soluble vitamins) and B12from the blood and stores themHepatic portal circulation-blood from stomach and small intestine carries nutrients and toxins to the liver
Filters blood from the GI tract thus acting to remove poisons and detoxify the blood◦Produces urea◦Destroys worn out red blood cells◦Produces blood proteinsRemoves iron, vitamins A, D, E, K (fat soluble vitamins) and B12from the blood and stores themHepatic portal circulation-blood from stomach and small intestine carries nutrients and toxins to the liver
Pancreatic juice carries this as well as other
What is the hepatic portal vein? Be able to identify it on a diagram.
This vein brings blood to the liver from the GI tract capillary bed.
Diabetes
When the blood glucose level rises rapidly, the pancreas produces an overload of insulin to bring the level under control and back to homeostasis. Type 1 diabetes occurs when the pancreas does not manufacture sufficient amounts of insulin. This condition is normally diagnosed in childhood. Type 2 diabetes occurs when the pancreas does not make enough insulin or when the body’s cells have become insulin-resistant. Type 2 diabetes normally occurs in adulthood with risk factors such as obesity, inactivity, and a family history of the disease (see Section 16.5).
It removes poisonous substances from the blood and detoxifies them.
How does the liver act as a sewage treatment plant?
False.
The liver is the largest organ in the body.
This is where the liver lies and is under.
Upper right section of the abdomenal cavity underneath the diaphragm.
The lobules are the structural and functional component of the lungs.
True or False.
If false- where are they found and how many?
Check out figure 9.8 B!
Now, go!
What is the liver?
Destroys old red blood cells; excretes bilirubin, a breakdown product of hemoglobin in bile, a liver product
The liver is also a storage organ. It removes iron and the vitamins A, D, E, K, and B12 from blood and stores them.
These are the vitamins that the liver stores, and the element that it removed from the blood.
The liver is also involved in blood glucose homeostasis. In the presence of insulin, the liver stores glucose as glycogen. When blood glucose becomes low, the liver releases glucose by breaking down Page 178glycogen. If need be, the liver converts glycerol (from fats) and amino acids to glucose molecules.
What role does the liver play in homeostasis?
Does the liver release insulin?
As amino acids are converted to glucose, the liver combines their amino groups with carbon dioxide to form urea, the usual nitrogenous waste product in humans.
How is urea formed?
Liver
Where are plasma proteins made?
This is another function of the liver related to regulation of blood levels.
The liver helps regulate blood cholesterol levels as well. Some cholesterol is converted to bile salts by the liver. Bile is a solution of bile salts, water, cholesterol, and bicarbonate. It has a yellowish-green color, because it also contains bilirubin, a pigment protein formed during the breakdown of hemoglobin, which is a process also performed by the liver. Bile is stored in the gallbladder, a pear-shaped organ just below the liver, until it is sent via the bile ducts to the duodenum. Gallstones form when liquid stored in the gallbladder hardens into pieces of stonelike material. In the small intestine, bile salts emulsify fat. When fat is emulsified, it breaks up into droplets. The droplets provide a large surface area that can be acted upon by digestive enzymes.
Other disorders of the rectum and colon
Disorders of the colon and rectumDiverticulosis–occurrence of pouches of mucosa from weak spots in the muscularislayer that can become infected often in the colonIrritable bowel syndrome(IBS) –muscularislayer contracts with power but without its normal coordination that is characterized by chronic diarrhea and abdominal painInflammatory bowel disease/colitis (IBD) –a group of inflammatory disorders such as ulcerative colitis or Crohn’sdiseasePolyps and cancer –small growths found in the epithelial lining that can be benign or cancerous
Need a lot of water to excrete our nitrogen based waste products like ureaAn overabundance of protein can result in dehydration during exercise and sweating.An overabundance of proteins can lead to calcium loss in urine which can lead to kidney stones.Eating red meat may lead to cardiovascular disease, since this protein source is high in saturated fats.9.6 Nutrition and Weight Control
These are liver disorders and the story behind them.
Hepatitis and cirrhosis are two serious diseases that affect the entire liver and hinder its ability to repair itself.
Therefore, they are life-threatening diseases.
When a person has a liver ailment, bile pigments may leak into the blood, causing jaundice. Jaundice is a yellowish tint to the whites of the eyes and to the skin of light-pigmented persons. Jaundice can result from hepatitis, inflammation of the liver.
Viral hepatitis occurs in several forms. Hepatitis A is usually acquired from sewage-contaminated drinking water and food.
Hepatitis B, which is usually spread by sexual contact, can also be spread by blood transfusions or contaminated needles. The hepatitis B virus is more contagious than the AIDS virus and is spread in the same way. Vaccines are available for hepatitis A and hepatitis B. Hepatitis C is usually acquired by contact with infected blood and can lead to chronic hepatitis, liver cancer, and death. There is not currently a vaccine for hepatitis C.
Cirrhosis is another chronic disease of the liver. First, the organ becomes fatty, and then liver tissue is replaced by inactive, fibrous scar tissue. Cirrhosis of the liver is often seen in alcoholics, due to malnutrition and the excessive amounts of alcohol (a toxin) the liver is forced to break down. Physicians have also observed cirrhosis of the liver in obese people, who are overweight due to a diet high in fatty foods.
The liver has amazing regenerative powers and can recover if the rate of regeneration exceeds the rate of damage. During liver failure, however, there may not be enough time to let the liver heal itself; liver transplantation is usually the preferred treatment. The liver is a vital organ, and its failure leads to death.
the nervous system and by digestive hormones
When you look at or smell food, the parasympathetic nervous system automatically stimulates gastric secretion.
The secretions of digestive juices are controlled/regulated by which system along with digestive hormones.
Gastrin. the stomach produces the hormone gastrin. Gastrin enters the bloodstream, and soon the secretory activity of gastric glands increases.
What happens when a person has eaten a meal particularly rich in protein.
These are two hormones produced by cells of the duodenal wall:
Cells of the duodenal wall produce two other hormones of particular interest—secretin and cholecystokinin (CCK). Secretin release is stimulated by acid, especially the HCl present in chyme. Partially digested proteins and fat stimulate the release of CCK. Soon after these hormones enter the bloodstream, the pancreas increases its output of pancreatic juice. Pancreatic juice buffers the acidic chyme entering the intestine from the stomach and helps digest food. CCK also causes the liver to increase its production of bile and causes the gallbladder to contract and release stored bile. The bile then aids the digestion of fats that stimulated the release of CCK. Figure 9.9 summarizes the actions of gastrin, secretin, and CCK.
Gallbladder
Muscular sac under liverStores and concentrates bile from the liver Bile is introduced into the duodenum in the presence of fatty foodThe hormone cholecystokinin from small intestine also regulates gall bladder: causes it to contract and release bile
Large intestine
cecum, the colon, the rectum, and the anal canal (Fig. 9.10). The large intestine is larger in diameter than the small intestine (6.5 cm compared with 2.5 cm), but it is shorter in length (see Fig. 9.1)
The large intestineincludes the cecum, colon, rectum, and anal canal.It is larger in diameter but shorter than the small intestine.Ileocecal valve to anus Cecum–saclike first part of the large intestineAppendix-hangs off of secum and contains lymphatic tissue that sometimes becomes inflamed (appendicitis)
Absorption of waterEliminates indigestible food from the body as fecesDoes not participate in digestion of foodGoblet cells produce mucus to act as a lubricantBacterial flora produce vitamin K and some B vitamins
The cecum is the first portion of the large intestine, joining the end of the small intestine. The cecum usually has a small projection called the vermiform appendix (the term vermiform describes its “wormlike” appearance) (Fig. 9.10). In humans, the appendix is thought to aid in fighting infections. Scientists have recently proposed that the appendix may also contribute to the population of needed bacteria in the large intestine. An inflamed appendix (appendicitis) may be treated using antibiotics or removed surgically. Should the appendix burst, the result can be peritonitis, a life-threatening swelling and infection of the peritoneum.
The colon includes the ascending colon, which goes up the right side of the body to the level of the liver; the transverse colon, which crosses the abdominal cavity just below the liver and the stomach; the descending colon, which passes down the left side of the body; and the sigmoid colon, which enters the rectum, the last 20 cm of the large intestine. The rectum opens at the anus, where defecation, the expulsion of feces, occurs.
Functions of the Large Intestine
The large intestine does not produce any digestive enzymes, and because the majority of nutrients processing occurred in the small intestine, it does not play a major role in the absorption of any nutrients except for some vitamins. The primary function of the large intestine is to absorb water, an important process to prevent dehydration of the body and maintain homeostasis.
The large intestine can absorb vitamins produced by intestinal flora, the bacteria that inhabit the intestine and aid in keeping us healthy. For many years it was believed that Escherichia coli were the major inhabitants of the colon, but culture methods now show that over 99% of the colon bacteria are other types of bacteria. The bacteria in the large intestine break down indigestible material and produce B-complex vitamins and most of the vitamin K needed by our bodies.
The large intestine forms feces. The consistency of normal feces is usually three-fourths water and one-fourth solid wastes. Bacteria, dietary fiber (indigestible remains), and other indigestible Page 180materials make up the solid wastes. Bacterial action on indigestible materials causes the odor of feces and accounts for the presence of gas. Stercobilin, which is a breakdown product of bilirubin (the yellow-orange bile pigment produced from the breakdown of hemoglobin), and oxidized iron cause the brown color of feces.
Defecation, ridding the body of feces, is also a function of the large intestine. Peristalsis occurs infrequently in the large intestine, but when it does, feces are forced into the rectum. Feces collect in the rectum until it is appropriate to defecate. At that time, stretching of the rectal wall initiates nerve impulses to the spinal cord. Shortly thereafter, the rectal muscles contract and the anal sphincters relax. This allows the feces to exit the body through the anus (Fig. 9.10). A person can inhibit defecation by contracting the external anal sphincter made of skeletal muscle. Ridding the body of indigestible remains is another way the digestive system helps maintain homeostasis.
Disorders of the colon and rectum
Disorders of the Colon and Rectum
The large intestine is subject to a number of disorders. Many of these can be prevented or minimized by a proper diet and hygiene.
Diarrhea
Diarrhea is characterized by bowel movements that are loose or watery. The major causes of diarrhea are infection of the lower intestinal tract and nervous stimulation. The intestinal wall becomes irritated, and peristalsis increases when an infection occurs. Water is not absorbed, and the diarrhea that results rids the body of the infectious organisms. In nervous diarrhea, the nervous system stimulates the intestinal wall and diarrhea results. Most people have several occurrences of diarrhea each year without suffering any health consequences. However, prolonged diarrhea can lead to dehydration because of water loss, which can lead to an imbalance of salts in the blood that can affect heart muscle contraction and potentially lead to death.
Constipation
When a person is constipated, the feces are dry and hard, making it difficult for them to be expelled. Diets that lack whole-grain foods, as well as ignoring the urge to defecate, are often the causes of constipation. When feces are not expelled regularly, additional water is absorbed from them. The material becomes drier, harder, and more difficult to eliminate. Adequate water and fiber intake can help regularity of defecation. The frequent use of laxatives is discouraged, because it can result in dependence on their use for normal bowel movements. If, however, it is necessary to take a laxative, the most natural is a bulk laxative. Like fiber, it produces a soft mass of cellulose in the colon. Lubricants such as mineral oil make the colon slippery; saline laxatives such as milk of magnesia act osmotically by preventing water from being absorbed. Some laxatives are irritants that increase peristalsis.
Chronic constipation is associated with the development of hemorrhoids, enlarged and inflamed blood vessels at the anus. Other contributing factors for hemorrhoid development include pregnancy, aging, and anal intercourse.
Diverticulosis
As mentioned previously (see Section 9.1), diverticulosis is the occurrence of little pouches of mucosa where food can collect. The pouches form when the mucosa pushes through weak spots in the muscularis. A frequent site is the last part of the descending colon.
Irritable Bowel Syndrome
Also mentioned previously (see Section 9.1), irritable bowel syndrome (IBS), or spastic colon, is a condition in which the muscularis contracts powerfully but without its normal coordination. The symptoms are abdominal cramps; gas; constipation; and urgent, explosive stools (feces discharge).
Inflammatory Bowel Disease
Inflammatory bowel disease (IBD) is a collective term for a number of inflammatory disorders. Ulcerative colitis and Crohn’s disease are the most common of these. Ulcerative colitis affects the large intestine and rectum and results in diarrhea, rectal bleeding, abdominal cramps, and urgency in defecation. Crohn’s disease is normally isolated to the small intestine but can affect any area of the digestive tract, including the colon and rectum. It is characterized by the breakdown of the lining of the affected area, resulting in ulcers. Ulcers are painful and cause bleeding, because they erode the submucosal layer, where there are nerves and blood vessels. This also results in the inability to absorb nutrients at the affected sites. Symptoms of Crohn’s disease include diarrhea, weight loss, abdominal cramping, anemia, bleeding, and malnutrition
SCIENCE IN YOUR LIFE
What is a fecal transplant?
The balance of bacteria, or microbiota, in the large intestine is important not only for the health of the digestive tract but for the entire individual. The use of antibiotics to control problems with the colon can alter the balance, allowing detrimental species of bacteria to dominate the colon, causing chronic diarrhea.
In a fecal material transplant, bacteria from a healthy individual are delivered to the colon using an enema, endoscopy, or oral pills to reestablish a healthy community of microbiota.
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Polyps and Cancer
The colon is subject to the development of polyps, small growths arising from the epithelial lining. Polyps, whether benign or cancerous, can be removed surgically. If colon cancer is detected while still confined to a polyp, the expected outcome is a complete cure. The American Cancer Society estimates that over 140,000 new cases of colon and rectal (colorectal) cancer are diagnosed per year in the United States. Some investigators believe that dietary fat increases the likelihood of colon cancer, because dietary fat causes an increase in bile secretion. It could be that intestinal bacteria convert bile salts to substances that promote the development of cancer. Fiber in the diet seems to inhibit the development of colon cancer, and regular elimination reduces the time during which the colon wall is exposed to any cancer-promoting agents in feces.
One diagnostic tool for all of these disorders is an endoscopic exam called a colonoscopy. In a colonoscopy, a flexible tube containing a camera is inserted into the GI tract, usually from the anus. The doctor may then examine the length of the colon, as well as take tissue samples (biopsies) for additional tests. However, as discussed in the Health feature “Swallowing a Camera,” this procedure is gradually being replaced by the PillCam, a camera you swallow.
Disorders of the colon and rectumDiarrhea–increased peristalsis and water is not reabsorbed due to either an infection or nervous stimulationConstipation–condition when feces are dry and hard that may be controlled with water and fiberHemorrhoids–enlarged and inflamed blood vessels of the anus due to chronic constipation, pregnancy, aging, and anal intercourse
Control of digestive activity
Control of digestive activityMostly controlled by reflexes via the parasympathetic division of the autonomic system (the ‘rest and digest’ division of control by the nervous system)Chemical and mechanical receptors are located in organ walls that trigger reflexesStimuli include:◦Stretch of the organ◦pH of the contents◦Presence of breakdown products9.5 The Large Intestine and Defecation31
Control of digestive activityReflexes include:◦Activation or inhibition of glandular secretions◦Smooth muscle activity
Obesity help!
When an individual is grossly overweight and has a body mass index (BMI)≥ 30BMI = (weight in pounds ÷height in inches)2x 703Healthy = 19.5-24.9BMI is a general guide to estimate how much of a person’s weight is due to adipose tissueBut it does nottake into account gender, fitness, or bone structure, so is only a general guide!
What are the obesity statistics for children and adults?
Obesity, or being significantly overweight, has become one of the greatest health problems in the United States. According to the Centers for Disease Control and Prevention (CDC), almost 36.5% of adults, and 17% of children, are classified as obese. These statistics are of great concern, because excess body fat is associated with a higher risk for premature death, type 2 diabetes, hypertension, cardiovascular disease, stroke, gallbladder disease, respiratory dysfunction, osteoarthritis, and certain types of cancer.
The Health feature “Searching for the Magic Weight-Loss Bullet” explains the various ways people have tried to keep their weight under control. The conclusion is that achieving or maintaining a healthy weight requires not only eating a variety of healthy foods but also exercising. In other words, to reverse a trend toward obesity, eat fewer calories by making wiser food choices and be more active.
How is obesity defined today? How do you calculate your BMI?
Today, obesity is often defined as having a body mass index (BMI) of 30 or greater. The body mass index uses a person’s height and weight (Fig. 9.11) to calculate a general approximation of his or her percent body fat. BMI can also be calculated by dividing weight in pounds (lb) by height in inches (in.) squared and multiplying by a conversion factor of 703. Using the metric system, the weight in kilograms (kg) is divided by the height in meters (m) squared:
BMI=weight(lb)height2(in.2)×703BMI=weight(kg)height2(m2)
Most people find it is easier to use a table (Table 9.3), figure (Fig. 9.11), or one of the many online calculators.
Table 9.3BMI Values
Table Summary:
ClassificationBMI Values
Healthy18.5–24.9
Overweight25.0–29.9
Obese30.0–39.9
Extremely obese40.0 and higher
Figure 9.11 The body mass index chart. Match your weight with your height, and then determine your body mass index (BMI). Healthy BMI = 18.5 to 24.9; overweight BMI = 25 to 29.9; obese BMI = 30 to 39.9; extremely obese BMI = 40 or more.
Source: U.S. Department of Agriculture, Dietary Guidelines for Americans, 2005.
Your BMI gives you an idea of how much of your weight is due to adipose tissue, commonly known as fat. In general, the taller you are, the more you could weigh without it being due to fat. Using BMI in this way works for most people, especially if they tend to be sedentary. But your BMI number should be used only as a general guide. It does not take into account fitness, bone structure, or gender. For example, a weightlifter’s BMI might fall in the obese range, not because of the amount of body fat but because of increased bone and muscle weight.
These are classes of nutrients
Classes of Nutrients
A nutrient can be defined as a required component of food that performs a physiological function in the body. Nutrients provide us with energy, promote growth and development, and regulate cellular metabolism.
Carbohydrates
Carbohydrates are either simple or complex (see Section 2.4). Glucose is a simple sugar preferred by the body as an energy source. Complex carbohydrates, consisting of multiple sugar units, are digested to glucose. Although body cells can use fatty acids as an energy source, brain cells require glucose.
Any product made from refined grains, such as white bread, cake, and cookies, should be minimized in the diet. During refinement, fiber is removed from the grains, along with vitamins and minerals, in order for the final product to be mainly starch. In contrast, sources of complex carbohydrates, such as beans, peas, nuts, fruits, and whole-grain products, are recommended as good sources of vitamins, minerals, and fiber (Fig. 9.12). Insoluble fiber adds bulk to fecal material and stimulates movements of the large intestine, preventing constipation. Soluble fiber combines with bile salts and cholesterol in the small intestine and prevents them from being absorbed.
Figure 9.12 Foods rich in fiber. Plants provide a good source of fiber in the diet. They also are a good source of vitamins and minerals when they are not processed (refined).
©Cole Group/Getty Images
Can carbs be harmful?
Can Carbohydrates Be Harmful?
Nutritionists now recognize that the high intake of refined carbohydrates and fructose sweeteners processed from cornstarch is contributing to the increase in obesity in the United States. In addition, these foods are said to have a high glycemic index (GI), because they quickly increase Page 183blood glucose. When the blood glucose level rises rapidly, the pancreas produces an overload of insulin to bring the level under control. Investigators tell us that a chronically high insulin level may lead to insulin resistance, type 2 diabetes, and increased fat deposition. Deposition of fat is associated with coronary heart disease, liver ailments, and several types of cancer.
Table 9.4 gives suggestions on how to reduce your intake of dietary sugars.
Table 9.4Reducing High-Glycemic-Index Carbohydrates
Table Summary: Table lists different ways to reduce dietary sugar that span multiple rows.
To Reduce Dietary Sugar
Eat fewer sweets, such as candy, soft drinks, ice cream, and pastries.
Eat fresh or frozen fruits or fruits canned without heavy syrup. Avoid artificial fruit juices.
Use less sugar—white, brown, or raw—and less honey and syrups.
Avoid sweetened breakfast cereals.
Eat less jelly, jam, and preserves.
When cooking, use spices, such as cinnamon, instead of sugar to flavor foods.
Do not put sugar in tea or coffee.
Avoid processed foods made from refined carbohydrates, such as white bread, rice, and pasta, and limit potato intake.
Carbohydrates are the preferred energy source for the body. The complex carbohydrates in whole grains, beans, nuts, and fruits contain fiber in addition to simple carbohydrates. Complex carbohydrate foods are often a good source of vitamins and minerals.
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Proteins
Dietary proteins are digested to amino acids (see Section 2.6), which cells use to synthesize hundreds of cellular proteins. Of the 20 different amino acids, 8 are essential amino acids that must be present in the diet because the body cannot make them, and 2 others are ones the body makes insufficiently. Eggs, milk products, meat, poultry, and most other foods derived from animals contain all 8 essential amino acids and are “complete,” or “high-quality,” protein sources. Legumes (beans and peas) (Fig. 9.13), other types of vegetables, seeds and nuts, and grains also supply us with amino acids. However, each of these alone is an incomplete protein source, because each is deficient in at least 1 of the essential amino acids. Absence of 1 essential amino acid prevents use of the other 19 amino acids. Therefore, vegetarians are counseled to combine two or more incomplete types of plant products to acquire all the essential amino acids. Tofu, soy milk, and other foods made from processed soybeans are complete protein sources. A balanced vegetarian diet is possible with a little knowledge and planning (see the Health Feature “Protein and Vegetarians”).
Figure 9.13 Foods rich in proteins and complex carbohydrates. Beans are a good source of complex carbohydrates and protein. But beans don’t supply all the essential amino acids. To ensure a complete source of protein in the diet, beans should be eaten in combination with a grain, such as rice.
©Birgit Reitz-Hofmann/Getty Images
BIOLOGY TODAY Health
Protein and Vegetarians
There are approximately 22.8 million vegetarians in the United States. Although definitions vary, most abstain from eating red meat, poultry, and fish. About a third of vegetarians are vegans, who avoid all animal products, while less stringent vegetarians may include eggs and/or dairy products as a part of their regular diet. Although vegetarianism is an important part of certain Eastern religions, most American vegetarians cite ethical or health reasons. Ethical concerns may include the treatment of animals raised as food, and/or the effects of animal agriculture on the environment. On the health side, most nutritional research seems to support the benefits of a low-fat, well-balanced vegetarian diet in reducing the incidence of cardiovascular disease, obesity, diabetes, and certain cancers, especially colon and prostate cancer.
Certain health risks are associated with vegetarian diets. Highly restricted vegetarian diets are probably not appropriate for pregnant or lactating women, or for very young children. Vegans, especially, have to be careful to obtain enough iron, vitamin D, vitamin B12, and certain fatty acids. However, most American vegetarians would likely agree that the most common question they are asked about their dietary habits is, “Where do you get your protein?” Many people believe that humans require meat in their diet in order to obtain sufficient protein. Adding to the confusion, in 1971, Frances Moore Lappé published Diet for a Small Planet, which advocated vegetarianism as a more ecologically sustainable diet. That book also introduced the concept of protein complementation, the idea that foods with insufficient levels of one or more essential amino acids needed to be ingested at the same time as foods higher in those amino acids. This idea has influenced American nutritionists for several decades, but in a later edition of her famous book, Lappé noted that with the exception of a few extreme diets, “if people are getting enough calories, they are virtually certain of getting enough protein.”
A position paper published in 2003 by the American Dietetic Association and Dietitians of Canada echoed these ideas, stating that “plant protein can meet requirements when a variety of plant foods is consumed and energy needs are met,” as well as “complementary proteins do not need to be consumed at the same meal.” Because proteins in plant food such as cereals may be harder to digest than animal proteins, vegetarians may need to include a higher percentage of protein in their diet. Beans, nuts, and legumes are particularly good protein sources, and according to the U.S. Food and Drug Administration, soybeans (Fig. 9C) contain complete protein, meaning that like animal protein, soy protein contains sufficient amounts of all essential amino acids for human nutrition. Soy may have other benefits. In October 1999, the FDA gave food manufacturers permission to put labels on products high in soy protein indicating that they may help lower heart disease risk.
Figure 9C Protein sources. For most adults, protein needs can be met by eating vegetables, such as soybeans, that contain high-quality proteins.
©McGraw-Hill Education/Andrew Resek, photographer
Questions to Consider
What are some of the challenges an individual faces when moving toward a meat-free diet?
In general, proteins are not stored by the body in the way that carbohydrates or fats can be stored. Considering this idea, why do you think the idea of complementary proteins became so well established?
A daily supply of essential amino acids is needed because they are not stored in the body, unlike the other amino acids, which can be stored as proteins and metabolized for cells’ needs. However, it does not take very much protein to meet the daily requirement. Two servings of meat a day (one serving is equal in size to a deck of cards) is usually plenty.
Can Proteins Be Harmful?
The liver removes the nitrogen-containing compound from an amino acid. By converting this portion to urea, the liver enables potentially toxic nitrogen to be removed from our bodies. However, large amounts of water are needed to properly excrete urea. Therefore, dehydration may occur if protein consumption is excessive. High-protein diets, especially those rich in animal proteins, can also increase calcium loss in urine. Excretion of calcium may lead to kidney stones and bone loss.
Certain types of meat, especially red meat, are known to be high in saturated fats; other sources of protein, such as chicken, fish, and eggs, are more likely to be low in saturated fats. As you recall from Section 5.7, excessive dietary saturated fat is a risk factor for cardiovascular disease.
Sufficient proteins are needed to supply the essential amino acids. Meat and dairy sources of protein may supply unwanted saturated fat, but vegetable sources do not.
Lipids
Fats, oils, and cholesterol are lipids (see Section 2.5). Saturated fats, which are solids at room temperature, usually have an animal origin. Two well-known exceptions are palm oil and coconut oil, which contain mostly saturated fats and come from the plants mentioned (Fig. 9.14). Butter and fats associated with meats (like the fat on steak and bacon) contain saturated fats.
Figure 9.14 Saturated and unsaturated fatty acids. This graph shows the percentages of saturated and unsaturated fatty acids in select fats and oils.
Oils contain unsaturated fatty acids, which do not promote cardiovascular disease. Corn oil and safflower oil are high in polyunsaturated fatty acids. Polyunsaturated oils are the only type of fat that contains linoleic acid and linolenic acid, two fatty acids the body cannot make. These fatty acids must be supplied by diet, so they are called essential fatty acids.
Olive oil and canola oil contain a larger percentage of monounsaturated fatty acids than other types of cooking oils. Omega-3 fatty acids—with a double bond in the third position—are believed to preserve brain function and protect against heart disease. Flaxseed contains abundant omega-3 fatty acids. Cold-water fish like salmon, sardines, and trout are also an excellent source.Page 186
Can Lipids Be Harmful?
The risk for cardiovascular disease is increased by a diet high in saturated fats and cholesterol. Saturated fats contribute to the formation of lesions associated with atherosclerosis inside the blood vessels. These lesions, called atherosclerotic plaques, limit the flow of blood through these vessels (see Section 5.7). Cholesterol is carried in the blood by the two transport proteins: high-density lipoprotein (HDL) and low-density lipoprotein (LDL). Cholesterol transported by HDL (the “good” lipoprotein) ends up in the liver, where the cholesterol is metabolized. Cholesterol carried by LDL (the “bad” lipoprotein) ends up being deposited in the tissues. Atherosclerotic plaques form when levels of HDL are low and/or when levels of LDL are high. Recommended levels of HDL and LDL can be reestablished by a diet low in saturated fats and cholesterol.
Trans fatty acids (trans fats) arise when unsaturated fatty acids are hydrogenated to produce a solid fat. The function of the plasma membrane receptors that clear cholesterol from the bloodstream may be reduced by trans fats, resulting in a higher blood cholesterol level. Trans fats are found in commercially packaged goods, such as cookies and crackers. Unfortunately, other snacks, such as microwave popcorn, may be sources as well. Be aware that any packaged goods containing partially hydrogenated vegetable oils or shortening contain trans fats. Some margarines used for home cooking or baking incorporate hydrogenated vegetable oil. Commercially fried foods, such as french fries from some fast-food chains, should be strictly limited in a healthy diet. Though tasty, these are often full of trans fats.Page 187
Table 9.5 gives suggestions on how to reduce dietary saturated fat and cholesterol. It is not a good idea to rely on commercially produced low-fat foods. In some products, the fat has been replaced by sugars; in some others, the fat has been replaced by protein.
Table 9.5Reducing Lipids in the Diet
Table Summary: Table lists different ways to reduce saturated fats and trans fats in the diet that span multiple rows.
To Reduce Saturated Fats and Trans Fats in the Diet
Choose poultry, fish, or dry beans and peas as a protein source.
Remove skin from poultry, and trim fat from red meats before cooking; place on a rack, so that fat drains off.
Broil, boil, or bake rather than fry.
Limit your intake of butter, cream, trans fats, shortenings, and tropical oils (coconut and palm oils).
Use herbs and spices to season vegetables instead of butter, margarine, or sauces. Use lemon juice instead of salad dressing.
Drink skim milk instead of whole milk, and use skim milk in cooking and baking.
To Reduce Dietary Cholesterol
Avoid cheese, egg yolks, liver, and certain shellfish (shrimp and lobster). Preferably, eat white fish and poultry.
Substitute egg whites for egg yolks in both cooking and eating.
Include soluble fiber in the diet. Oat bran, oatmeal, beans, corn, and fruits, such as apples, citrus fruits, and cranberries, are high in soluble fiber.
Unsaturated fats such as those in oils do not lead to cardiovascular disease and are preferred. Fats and oils contain many more calories per gram than do carbohydrates and protein.
Minerals
Minerals are divided into major minerals and trace minerals. Major minerals are needed at quantities greater than 100 milligrams (mg) per day. Trace minerals are needed at levels less than 100 mg per day. Table 9.6 lists selected minerals and gives their functions and food sources.
Table 9.6Minerals
Table Summary: Table lists the names of different types of minerals grouped into two categories, on the basis of minimum and maximum quantity, in column 1. The functions and food sources of each type of mineral in both the groups appear in columns 2 and 3. The health concerns related to each mineral are further listed in columns 4 and 5, with deficiency and toxicity as their column headings.
MineralFunctionsFood SourcesHealth Concerns
DeficiencyToxicity
Major (More than 100 mg/Day Needed)
Calcium +(Ca2+)Strong bones and teeth, nerve conduction, muscle contraction, blood clottingDairy products, leafy green vegetablesStunted growth in children, low bone density in adultsKidney stones, interferes with iron and zinc absorption
Phosphorus (PO43−)Bone and soft tissue growth; part of phospholipids, ATP, and nucleic acidsMeat, dairy products, sunflower seeds, food additivesWeakness, confusion, pain in bones and jointsLow blood and bone calcium levels
Potassium +(K+)Nerve conduction, muscle contractionMany fruits and vegetables, branParalysis, irregular heartbeat, eventual deathVomiting, heart attack, death
Sulfur (S2−)Stabilizes protein shape, neutralizes toxic substancesMeat, dairy products, legumesNot likelyIn animals, depresses growth
Sodium +(Na+)Nerve conduction, pH and water balanceTable saltLethargy, muscle cramps, loss of appetiteEdema, high blood pressure
Chloride (Cl−)Water balanceTable saltNot likelyVomiting, dehydration
Magnesium +(Mg2+)Part of various enzymes for nerve and muscle contraction, protein synthesisWhole grains, leafy green vegetablesMuscle spasm, irregular heartbeat, convulsions, confusion, personality changesDiarrhea
Trace (Less than 100 mg/Day Needed)
Zinc +(Zn2+)Protein synthesis, wound healing, fetal development and growth, immune functionMeats, legumes, whole grainsDelayed wound healing, stunted growth, diarrhea, mental lethargyAnemia, diarrhea, vomiting, renal failure, abnormal cholesterol levels
Iron +(Fe2+)Hemoglobin synthesisWhole grains, meats, prune juiceAnemia, physical and mental sluggishnessIron toxicity disease, organ failure, eventual death
Copper +(Cu2+)Hemoglobin synthesisMeat, nuts, legumesAnemia, stunted growth in childrenDamage to internal organs if not excreted
Iodine (I−)Thyroid hormone synthesisIodized table salt, seafoodThyroid deficiencyDepressed thyroid function, anxiety
Selenium (SeO43−)Part of antioxidant enzymeSeafood, meats, eggsVascular collapse, possible cancer developmentHair and fingernail loss, discolored skin
Manganese +(Mn2+)Part of enzymesNuts, legumes, green vegetablesWeakness and confusionConfusion, coma, death
The major minerals are constituents of cells and body fluids and are structural components of tissues. The trace minerals are often part of larger molecules. For example, iron (Fe2+) is present in hemoglobin, and iodine (I−) is a part of hormones produced by the thyroid gland. Zinc (Zn2+), copper (Cu2+), and manganese (Mn2+) are present in enzymes that catalyze a variety of reactions. As research continues, more and more elements are added to the list of trace minerals considered essential. During the past three decades, for example, very small amounts of selenium, molybdenum, chromium, nickel, vanadium, silicon, and even arsenic have been found to be essential to good health. Table 9.6 also provides signs of deficiency and toxicity for the selected minerals.
Occasionally, individuals do not receive enough iron (especially women), calcium, magnesium, or zinc in their diets. Adult females need more iron in their diet than males (8–18 mg compared with 8–11 mg), because they lose hemoglobin each month during menstruation. Stress can bring on a magnesium deficiency, and due to its high-fiber content, a vegetarian diet may make zinc less available to the body. However, a varied and complete diet usually supplies enough of each type of mineral.
Calcium
Calcium (Ca2+) is a major mineral needed for the construction of bones and teeth. It is also necessary for nerve conduction, muscle contraction, and blood clotting. Many people take calcium supplements to prevent or counteract osteoporosis, a degenerative bone disease that afflicts an estimated one-fourth of older men and one-half of older women in the United States. Osteoporosis develops because bone-eating cells called osteoclasts are more active than bone-forming cells called osteoblasts. The bones become porous, and they break easily because they lack sufficient calcium. Recommended calcium intakes vary by age, but in general 1,000 mg a day is recommended for men and women. After age 50 in women, and 70 in men, this increases to 1,200 mg a day. For many people, calcium supplements are needed to obtain these levels.
Osteoporosis
Small-framed Caucasian women with a family history of osteoporosis are at greatest risk of developing the disease. Smoking and drinking more than nine cups of caffeinated drinks daily may also contribute. Vitamin D is an essential companion to calcium in preventing osteoporosis. Other vitamins may also be helpful; for example, magnesium has been found to suppress the cycle that leads to bone loss. In addition to adequate calcium and vitamin intake, exercise helps prevent osteoporosis. Medications are also available that slow bone loss while increasing skeletal mass.
Sodium
Sodium plays a major role in regulating the body’s water balance, as does chloride (Cl−). Sodium plays an important role in the movement of materials across the plasma membrane (see Section 3.3), as well as the conduction of a nerve impulse (see Section 14.1). The recommended amount of sodium intake per day is 1,500 mg, although the average American takes in more than 3,400 mg every day. This Page 188imbalance has caused concern, because sodium in the form of salt intensifies hypertension (high blood pressure). About one-third of the sodium we consume occurs naturally in foods. Another third is added during commercial processing, and we add the last third either during home cooking or at the table in the form of table salt.
Clearly, it is possible to cut down on the amount of sodium in the diet. Table 9.7 gives recommendations for doing so.
Table 9.7Reducing Dietary Sodium
Table Summary: Table lists the different ways to reduce dietary sodium that span multiple rows.
To Reduce Dietary Sodium
Use spices instead of salt to flavor foods.
Add little or no salt to foods at the table, and add only small amounts of salt when you cook.
Eat unsalted crackers, pretzels, potato chips, nuts, and popcorn.
Avoid hot dogs, ham, bacon, luncheon meats, smoked salmon, sardines, and anchovies.
Avoid processed cheese and canned or dehydrated soups.
Avoid brine-soaked foods, such as pickles and olives.
Read nutrition labels to avoid high-salt products.
SCIENCE IN YOUR LIFE
Where does most of the sodium in the diet come from?
Contrary to popular belief, the majority of the sodium in your diet does not come from the salt you put on your food when you are eating. Instead, most of our sodium (over three-quarters!) comes from processed foods and condiments. Sodium is used in these items both to preserve the food or condiment and to make it taste better. But sometimes the amount of sodium is phenomenal. A single teaspoon of soy sauce contains almost 1,000 mg of sodium, and a half-cup of prepared tomato sauce typically has over 400 mg of sodium. Websites such as nutritiondata.self.com can help you track your daily sodium intake.
Vitamins
Vitamins are organic compounds (other than carbohydrate, fat, and protein) that the body uses for metabolic purposes but is unable to produce in adequate quantity. Many vitamins are portions of coenzymes, enzyme helpers. For example, niacin is part of the coenzyme NAD, and riboflavin is part of another dehydrogenase, FAD (see Section 3.6). Coenzymes are needed in only small amounts, because each can be used over and over. Not all vitamins are coenzymes. Vitamin A, for example, is a precursor for the visual pigment that prevents night blindness. If vitamins are lacking in the diet, various symptoms develop. There are 13 vitamins, divided into those that are fat soluble (Table 9.8) and those that are water soluble (Table 9.9). The differences between fat-soluble and water-soluble vitamins have to do with how the compound gets absorbed into the body, how it is transported by the body, its interaction with body tissues, and how it is stored in the cells.
B Vitamins
Table 9.8Fat-Soluble Vitamins
Table Summary: Table lists the names of different types of vitamins in column 1. The functions and food sources of each type of vitamin appear in columns 2 and 3. The health concerns related to each vitamin are further listed in columns 4 and 5, with deficiency and toxicity as their column headings.
VitaminFunctionsFood SourcesHealth Concerns
DeficiencyToxicity
Vitamin AAntioxidant synthesized from beta-carotene; needed for healthy eyes, skin, hair, and mucous membranes and for proper bone growthDeep yellow/orange and leafy, dark green vegetables; fruits; cheese; whole milk; butter; eggsNight blindness, impaired growth of bones and teethHeadache, dizziness, nausea, hair loss, abnormal development of fetus
Vitamin DGroup of steroids needed for development and maintenance of bones and teeth and for absorption of calciumMilk fortified with vitamin D, fish liver oil; also made in the skin when exposed to sunlightRickets, decalcification and weakening of bonesCalcification of soft tissues, diarrhea, possible renal damage
Vitamin EAntioxidant that prevents oxidation of vitamin A and polyunsaturated fatty acidsLeafy green vegetables, fruits, vegetable oils, nuts, whole-grain breads and cerealsUnknownDiarrhea, nausea, headaches, fatigue, muscle weakness
Vitamin KNeeded for synthesis of substances active in clotting of bloodLeafy green vegetables, cabbage, cauliflowerEasy bruising and bleedingCan interfere with anticoagulant medication
Table 9.9Water-Soluble Vitamins
Table Summary: Table lists the names of different types of water-soluble vitamins in column 1. The functions and food sources of each type of water-soluble vitamin appear in columns 2 and 3. The health concerns related to each water-soluble vitamin are further listed in columns 4 and 5, with deficiency and toxicity as their column headings.
VitaminFunctionsFood SourcesHealth Concerns
DeficiencyToxicity
Vitamin CAntioxidant; needed for forming collagen; helps maintain capillaries, bones, and teethCitrus fruits, leafy green vegetables, tomatoes, potatoes, cabbageScurvy, delayed wound healing, infectionsGout, kidney stones, diarrhea, decreased copper
Thiamine (vitamin B1)Part of coenzyme needed for cellular respiration; also promotes activity of the nervous systemWhole-grain cereals, dried beans and peas, sunflower seeds, nutsBeriberi, muscular weakness, enlarged heartCan interfere with absorption of other vitamins
Riboflavin (vitamin B2)Part of coenzymes, such as FAD; aids cellular respiration, including oxidation of protein and fatNuts, dairy products, whole-grain cereals, poultry, leafy green vegetablesDermatitis, blurred vision, growth failureUnknown
Niacin (nicotinic acid)Part of coenzyme NAD; needed for cellular respiration, including oxidation of protein and fatPeanuts, poultry, whole-grain cereals, leafy green vegetables, beansPellagra, diarrhea, mental disordersHigh blood sugar and uric acid, vasodilation, etc.
Folacin (folic acid)Coenzyme needed for production of hemoglobin and formation of DNADark, leafy green vegetables; nuts; beans; whole-grain cerealsMegaloblastic anemia, spina bifidaMay mask B12 deficiency
Vitamin B6Coenzyme needed for synthesis of hormones and hemoglobin; CNS controlWhole-grain cereals, bananas, beans, poultry, nuts, leafy green vegetablesRarely, convulsions, vomiting, seborrhea, muscular weaknessInsomnia, neuropathy
Pantothenic acidPart of coenzyme A needed for oxidation of carbohydrates and fats; aids in the formation of hormones and certain neurotransmittersNuts, beans, dark green vegetables, poultry, fruits, milkRarely, loss of appetite, mental depression, numbnessUnknown
Vitamin B12Complex, cobalt-containing compound; part of the coenzyme needed for synthesis of nucleic acids and myelinDairy products, fish, poultry, eggs, fortified cerealsPernicious anemiaUnknown
BiotinCoenzyme needed for metabolism of amino acids and fatty acidsGenerally in foods, especially eggsSkin rash, nausea, fatigueUnknown
FAD = flavin adenine dinucleotide; NAD = nicotinamide adenine dinucleotide
Page 189
Antioxidants
Over the past several decades, numerous statistical studies have determined that a diet rich in fruits and vegetables can protect against cancer. Cellular metabolism generates free radicals, unstable molecules that carry an extra electron. The most common free radicals in cells are superoxide (O2−) and hydroxide (OH−). To stabilize themselves, free radicals donate an electron to DNA, to proteins (including enzymes), or to lipids, which can be found in plasma membranes. Such donations often damage these cellular molecules and thereby may lead to disruptions of cellular functions, including even cancer.
Page 190Vitamins C, E, and A are believed to defend the body against free radicals and are therefore termed antioxidants. These vitamins are especially abundant in fruits and vegetables. Dietary guidelines suggest we increase our consumption of fruits and vegetables each day. To achieve this goal, think in terms of salad greens, raw or cooked vegetables, dried fruit, and fruit juice, in addition to apples and oranges and other fresh fruits.
Dietary supplements may provide a potential safeguard against cancer and cardiovascular disease. Nutritionists do not think people should take supplements instead of improving their intake of fruits and vegetables. There are many beneficial compounds in these foods that cannot be obtained from a vitamin pill. These compounds enhance one another’s absorption or action and perform independent biological functions.
Vitamin D
Skin cells contain a precursor cholesterol molecule converted to vitamin D after UV exposure. Vitamin D leaves the skin and is modified first in the kidneys and then in the liver until finally it becomes calcitriol. Calcitriol promotes the absorption of calcium by the intestines. When taking a calcium supplement, it is a good idea to get one with added vitamin D. The lack of vitamin D leads to rickets in children. Rickets, characterized by bowing of the legs, is caused by defective mineralization of the skeleton. Most milk is fortified with vitamin D, which helps prevent the occurrence of rickets.
How to Plan Nutritious Meals
Many serious disorders in Americans are linked to a diet that results in excess body fat. Whereas genetics is a factor in being overweight, a person cannot become fat without taking in more food energy (calories) than is needed. People need calories (energy) for their basal metabolism. Basal metabolism is the number of calories a person’s body burns at rest to maintain normal body functions. A person also needs calories for exercise. The less exercise, the fewer calories needed beyond the basal metabolic rate. So the first step in planning a diet is to limit the number of calories to an amount the person will use each day. Let’s say you do all the necessary calculations (beyond the scope of this book). You discover that, as a woman, the maximum number of calories you can take in each day is 2,000. If you’re a man, you can afford 2,500 calories without gaining weight.
The new guidelines developed by the U.S. Department of Agriculture (USDA) are called MyPlate (Fig. 9.15). This graphical representation replaced the older pyramids because most people found the plate graphic easier to interpret. It can be used to help you decide how those calories should be distributed among the foods to eat. MyPlate emphasizes the proportions of each food group that should be consumed daily.
Figure 9.15 The MyPlate dietary recommendations. The U.S. Department of Agriculture (USDA) developed this visual representation of a food plate as a guide to better health. The size differences on the plate for each food group suggest what portion of your meal should consist of each category. The five different colors illustrate that each food category, in correct proportions, is needed each day for good health. See ChooseMyPlate.gov.
Source: USDA, ChooseMyPlate.gov website
In 2015, the U.S. Department of Health and Human Services and the U.S. Department of Agriculture released a new set of dietary guidelines that focuses more on healthy eating patterns than on strict amounts of nutrients. These guidelines are outlined in the Health feature “New Dietary Guidelines.”
BIOLOGY TODAY Health
New Dietary Guidelines
Dietary guidelines are typically revised by the U.S. government every 5 years to reflect changes in nutrition science. The latest guidelines were released in 2015 by the Departments of Agriculture and Health and Human Services. The overall purposes of these guidelines were to:
Promote health.
Prevent chronic (long-term) disease.
Assist people in reaching and maintaining a healthy weight.
The new guidelines focus less on prescribing quantitative levels for nutrients, and more on establishing healthy eating patterns. These patterns include the following foods:
A variety of vegetables, including leafy vegetables, beans, red and yellow vegetables, and starches.
Fruits.
Grains. At least half of all grains should be whole grains.
Fat-free or low-fat dairy products (including soy).
Proteins in the form of seafood, lean meats, poultry, eggs, legumes, nuts, and soy products.
Oils.
To establish these healthy eating patterns, specific recommendations were made to limit certain nutrients that are recognized as raising health concerns:
Consume less than 10 percent of calories per day from added sugar.
Consume less than 10 percent of calories per day from saturated fats.
Consume less than 2,300 milligrams (mg) per day of sodium.
Alcohol should be consumed only in moderation. A maximum of one drink per day for women and up to two drinks per day for men (and only by adults of legal drinking age).
For more information on these guidelines, including the science of how they were determined, visit health.gov/dietaryguidelines/2015/guidelines/.
Questions to Consider
Why do you think quantitative values were removed for many of the nutrients?
Reflect on your diet over the past 24 hours. How does your diet relate to these general guidelines?
Eat a variety of foods. Foods from all food groups should be included in the diet.
Eat more of these foods: fruits, vegetables, whole grains, and fat-free or low-fat milk products. Choose dark green vegetables, orange vegetables, and leafy vegetables. Dry beans and peas are good sources of fiber and a great protein source as well. Limit potatoes and corn. When eating grains, choose whole grains, such as brown rice, oatmeal, and Page 191whole-wheat bread. Choose fruit as a snack or a topping for foods, instead of sugar.
Choose lean meats, such as poultry, and fish high in omega-3 fatty acids, such as salmon, trout, and herring, in moderate-sized portions. Include oils rich in monounsaturated and polyunsaturated fatty acids in the diet.
Eat less of foods high in saturated or trans fats, added sugars, cholesterol, salt, and alcohol.
Be physically active every day. If you need to lose weight, decrease your calorie intake slowly while maintaining an adequate nutrient intake and increasing your physical activity.
Eating Disorders
People with eating disorders are dissatisfied with their body image. Social, cultural, emotional, and biological factors all contribute to the development of an eating disorder. Serious conditions such as obesity, anorexia nervosa, and bulimia nervosa can lead to malnutrition, disability, and death. Regardless of the eating disorder, early recognition and treatment are crucial.
Anorexia nervosa is a severe psychological disorder characterized by an irrational fear of getting fat. Victims refuse to eat enough food to maintain a healthy body weight (Fig. 9.16a). A self-imposed starvation diet is often accompanied by occasional binge eating, followed by purging and extreme physical activity to avoid weight gain. Binges usually include large amounts of high-calorie foods, and purging episodes involve self-induced vomiting and laxative abuse. About 90% of people suffering from anorexia nervosa are young women; an estimated 1 in 200 teenage girls is affected.
Figure 9.16 The characteristics of different eating disorders. a. People with anorexia nervosa have a mistaken body image and think they are fat, even though they are thin. b. Those with bulimia nervosa overeat and then purge their bodies of the food they have eaten. c. People with muscle dysmorphia think their muscles are underdeveloped. They spend hours at the gym and are preoccupied with diet as a way to gain muscle mass.
(a): ©Ted Foxx/Alamy; (b): ©Donna Day/The Image Bank/Getty Images; (c): ©Kevin Dodge/Corbis/Getty Images Plus
Page 192A person with bulimia nervosa binge eats and then purges to avoid gaining weight (Fig. 9.16b). The cyclical binge-purge behavior can occur several times a day. People with bulimia nervosa can be difficult to identify, because their body weights are often normal and they tend to conceal their bingeing and purging practices. Women are more likely than men to develop bulimia; an estimated 4% of young women suffer from this condition.
Other abnormal eating practices include binge-eating disorder and muscle dysmorphia. Many obese people suffer from binge-eating disorder, a condition characterized by episodes of overeating without purging. Stress, anxiety, anger, and depression can trigger food binges. A person suffering from muscle dysmorphia (Fig. 9.16c) thinks his or her body is underdeveloped. Bodybuilding activities and a preoccupation with diet and body form accompany this condition. The person may spend hours in the gym every day, working out on muscle-strengthening equipment. Unlike anorexia nervosa and bulimia, muscle dysmorphia affects more men than women.
CHECK YOUR PROGRESS 9.6
Briefly describe and give an example of each class of nutrients.
Answer
Carbohydrates are simple or complex sugar units used as energy sources. They include products made from refined grains, beans, peas, nuts, fruits, and whole-grain products. Proteins are long chains of amino acids the body breaks down to make other proteins. They are found in meat, eggs, and milk. Lipids are cholesterol or fats and oils that contain either saturated or unsaturated fatty acid chains used for energy storage. Olive oil contains high levels of monounsaturated fat. Minerals are elements needed either in larger quantities (calcium, phosphorus) or trace quantities (zinc, iron). Vitamins are other organic compounds the body cannot synthesize, like vitamins A, D, E, and K.
Discuss why carbohydrates and fats might be the cause of the obesity epidemic today.
Answer
Carbohydrates and fats store lots of energy, they are consumed in excess, and with a sedentary lifestyle are not burned off with exercise but instead stored as fat.
Explain the difference between a vitamin and mineral.
Answer
Vitamins are organic molecules that cannot be synthesized by the body, whereas minerals are chemical elements needed in various amounts by the body.
CONNECTING THE CONCEPTS
For more information on how the body utilizes nutrients, refer to the following discussions:
Section 12.1 explains how vitamin D acts as a hormone that influences bone growth.
Section 15.4 examines the role of vitamin A in vision.
Section 20.2 examines how a diet with adequate levels of vitamins A and C may help prevent cancer.
CONCLUSION
Celiac disease is a serious condition that affects roughly 1 out of every 100 individuals. Unlike gluten sensitivity, which has many of the same symptoms, celiac disease can cause severe damage to the villi and microvilli lining of the small intestine.
As we have seen in this chapter, the small intestine plays a central role in the processing of nutrients. Any condition that damages the villi and microvilli reduces the effectiveness of the small intestine and can result in weight loss, vitamin and mineral deficiencies, and even cancer of the intestines. Currently, the only treatment for celiac disease is a lifelong diet that strictly avoids exposure to the gluten protein.d
This is general nutritional information I can break down later
Lecture notes on obesity and why we should be worried about being tubby
Incidence has doubled in the US in the last 20 yearsIn the US ~1/3 of adults are obese and it is now prevalent in children and adolescentsIs associated with an increased risk of premature death, Type 2 diabetes, hypertension, cardiovascular disease, stroke, gallbladder disease, respiratory dysfunction, osteoarthritis, and certain cancersObesity tends to increase with an increase in income.
Magic Bullet Diets
Trendy diet programs◦Pritikindiet: high carbohydrate and fiber diet through whole grains and vegetables◦Atkins: low-carbohydrate, and high protein and fat diet◦Zone and South beach diets: low carbohydrate diets that are high in protein and “healthy” fats◦Paleo/Caveman diet: tries to follow diets of humans before agriculture was done, i.e., low/no carbsPrescription drugsAlli-interferes with fat absorption in small intestine
Surgical procedures◦Gastroplasty: stapling or partitioning of a small portion of the stomach◦Gastric bypass: attaching the lower part of the small intestine to the stomach so most of the food bypasses the stomach and small intestine◦Gastric banding: a constriction band is used to reduce stomach size◦Liposuction: removal of fat cells; best used for overweight people that are not obese or morbidly obese9.6 Nutrition and Weight Control
Exercise◦This is important to build in any weight loss regimen, as expenditure of calories over intake of calories is important and easily accomplished with exercise◦A minimum of 10,000 steps should be taken a day for weight maintenance and health◦12,000-15,000 steps should be taken a day to promote weight loss
To understand weight and nutrition, we first have to understand nutrientsNutrientsare components of food that are needed to perform physiological body functions.Nutrients include:◦carbohydrates◦proteins◦lipids◦minerals◦vitamins
What are nutrients?
Carbohydrates
CarbohydratesCarbohydrates are sugars or polysaccharides that are digested into the simple sugars which are an important energy source.Refined grains should be minimized in the diet because fiber and vitamins are removed (i.e., white bread, cake, and cookies).Complex carbohydrates are recommended as a good source of vitamins and minerals (i.e., beans, whole-grain products, nuts, and fruits).
Can carbohydrates be harmful?Refined sugars and fructose sweeteners may contribute to obesity; have a high glycemic index (quickly increase blood glucose)These foods may cause the pancreas to secrete large amounts of insulin which can lead to insulin resistance seen in type 2 diabetes and increased resistance to fat metabolism.An increase in fat deposition may increase the risk of coronary heart disease, liver diseases, and certain cancers.
What about proteins?
ProteinsProteins are digested into 20 different amino acids which are used to produce cellular proteins. All 20 must be present to be used.Essential amino acids are the 8 amino acids that mustbe attained through diet (our bodies can’t make them). Complete proteins, that have all essential amino acids, are usually derived from animals such as meat and dairy. Non-animal sources of complete proteins are tofu, soymilk, and other processed food from soybeans.
Incomplete proteins are ones that lack at least one essential amino acid (i.e., legumes, nuts, grains, etc.) and need to be combined with another incomplete protein to allow all amino acids to be used in the body.Amino acids cannot be stored in the body, thus small amounts (2 meat servings) need to be ingested on a daily basis.
- Lipids
LipidsLipidsinclude fats, oils, and cholesterol.Saturated fats (usually of animal origin: butter, lard) are usually solid at room temperature, while unsaturated fats are usually liquid at room temperature(example: olive and canola oil.Essential fatty acids are ones that must be ingested; they include linoleic acid and linolenic acid (these can only be found in polyunsaturated oils such as corn and safflower).9.6 Nutrition and Weight Control
see choosing healthy oil slide and see other slides
Can lipids be harmful?CVD is often a result of arteries blocked by plaques/lesions made of cholesterol and saturated fatsLow density lipoproteins (LDL) is the “bad” cholesterol because it carries cholesterol from the liver to the cellsLDL is increased by saturated fats and decreased by unsaturated fatsHigh density lipoproteins (HDL) is the “good” cholesterol because it carries cholesterol to the liver where it is converted to bile saltsTrans-fatty acids are not found in nature◦Made by hydrogenation of unsaturated fatty acids for commercial products and may reduce the ability of cells to clear cholesterol from the bloodstream9.6 Nutrition and Weight Control17
See other slide on cholesterol
Supplments and nutritional info
MineralsMajor minerals make up components of cells, body fluids, and tissues (i.e., calcium). You need them at quantities more than 100 mg/dayMinor minerals are components of larger molecules (i.e., iron in hemoglobin). You need them less than 100 mg/dayA varied and complete diet usually provides necessary minerals.9.6 Nutrition and Weight Control19
CalciumCalciumis needed to make bone, nerve impulse conduction, and muscle contraction.1,000 mg/day are recommended to keep bones healthy early in life and 1200 mg/day after 50 years of age in females, 70 years of age in males.Vitamin D is needed with calcium to prevent bone loss (osteoporosis).9.6 Nutrition and Weight Control20
SodiumSodium is needed for regulating water balance.500 mg/day is the recommended amount (on average each American takes in 4,000 -4,700 mg/day!).Sodium can increase hypertension in people who already have it.9.6 Nutrition and Weight Control21
Minerals229.6 Nutrition and Weight Control
VitaminsOrganic compounds (not including proteins, fats, or carbohydrates) are used for metabolism but not produced in high enough quantities by the body.Vitamins are often enzyme helpers (coenzymes).There are a total of 13 vitamins in two groups: fat-soluble (A,D,E,K) and water-soluble (everything else other than A,D,E,K)9.6 Nutrition and Weight Control23
Fat-soluble vitamins9.6 Nutrition and Weight Control24
Water-soluble vitamins9.6 Nutrition and Weight Control25
AntioxidantsFree-radicals–unstable molecules that donate an electron to DNA, proteins, and/or fats in plasma membranes (this leads to cellular damage)Antioxidantsare chemicals that decrease the rate of oxidation or transfer of electrons.Vitamin C, E, and A are considered antioxidants because they are thought to defend the body against free radicals The vitamins are common in fruits and vegetables: ingesting it from food are better than supplements9.6 Nutrition and Weight Control26
- 6 Nutrition and Weight ControlFood label animationBelow is a great explanation of a food label. This was also in Ch. 2 as well, but it fits in nicely here as well!You must be connected to the internet to view this animation and click on the link!http://www.viddler.com/embed/da38cdeb27
- 6 Nutrition and Weight ControlHow to plan nutritious mealsYou do need to consume calories to run your body right!Basal metabolism = number of calories you burn at rest to maintain normal body functionsThe U.S. Department of Agriculture (USDA) has guidelines of the proportions of nutrients you need called “choosemyplate.gov”◦Eat a variety of foods◦Eat more of fruits and veggies, whole grains. fat-free or low-fat milk28
- 6 Nutrition and Weight ControlChoosemyplate.gov29Copyright © McGraw-Hill Education. Permission required for reproduction or display.FruitsGrains ProteinVegetables Dairy ChooseMyPlate.gov
Eating disorders
Eating disordersAnorexia nervosa –psychological disorder due to fear of getting fat; usually results in self-induced starvation, high physical activity, and may include purgingBulimia nervosa –disorder in which people eat large amounts of high-cloriefood (binge-eating) followed by purging to avoid weight gain, often more than once a day9.6 Nutrition and Weight Control30
Eating disordersBinge-eating disorder –obese people are afflicted; overeating is not followed by purging, and this can lead to depression, anger, anxiety, and more bingesMuscle dysmorphia –characterized by people that think their bodies are underdeveloped and are often preoccupied with body-building activities and diet9.6 Nutrition and Weight Control31
Eating disorders are associated with body imageFigure 9.16 The characteristics of different eating disorders.9.6 Nutrition and Weight ControlCopyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.a. Anorexia nervosab. Bulimia nervosac. Muscle dysmorphiaa: © Ted Foxx/Alamy RF; b: © Donna Day/Stone/Getty Images; c: © Corbis RF32
