Ch 19 Digestive System Flashcards
How does the digestive system maintain homeostasis?
Maintains homeostasis by taking in food and water and then eliminating the waste products
Functions of the digestive system are carried out by the organs of the alimentarycanal or gastrointestinal tract (GI tract) and accessory organs
What are organs of the alimentary canal ?
Pharynx, esophagus, stomach, small intestine, large intestine, rectum, and anal canal
What are Accessory organs ?
Teeth, tongue, salivary glands, liver, gallbladder, and pancreas
What do salivary glands do?
Accessory organ
Secrete saliva, which contain enzymes that initiate breakdown of carbohydrates
What does mouth do?
alimentary canal
mechanical breakdown of food
chemical digestion of carbs begins
what does pharynx do ?
alimentary canal
connects mouth to esophagus
What does esophagus do?
alimentary canal
peristalsis pushes food to stomach
behind the trachea
What does stomach do?
alimentary canal
secretes acid and enzymes; mixes food with secretions to begin enzymatic digestion of proteins
What does small intestine do?
alimentary canal
mixes food with bile and pancreatic juice
final enzymatic breakdown of food molecules
main site of nutrient absorption
What does the large intestine do?
alimentary canal
absorbs water and electrolytes to form poop
What does rectum do?
alimentary canal
regulates elimination of poop
What is ingestion?
Function of digestive system
Eating and drinking
What is Secretion?
Function of digestive system
Saliva, water, acids, and enzymes enter the mouth and GI tract to help with the breakdown and absorption of foods.
What is Mixing and propulsion?
Function of digestive system
Move food along its way to the anal canal
What is Digestion?
Function of digestive system
Break down food into small molecules
Mechanical digestion begins in the mouth with the mastication of food.
Chemical digestion involves the further breakdown of food by the enzymes secreted by salivary glands, stomach, pancreas, and small intestine.
What is Absorption ?
Function of digestive system
Into the blood and lymph
takes place within the GI tract lumen by epithelial surface layer
What is Defecation
Function of digestive system
Elimination of wastes, indigestible substances, unabsorbed substances, water, some cells, and bacteria
Describe the mouth and its functions
Oral or buccal cavity
Takes in food and reduces its size through mastication
Starts the process of chemical digestion when saliva (has amylase) breaks down carbs
Boundaries are cheek, lips, hard/soft palate
What is the vestibule?
Space located between the lips and cheeks and the teeth
What is the oral cavity proper/
Space behind the teeth
What do the cheeks do?
Hold food in the mouth
Skin, adipose tissue, skeletal muscles, and an inner lining of moist nonkeratinized stratified squamous epithelium
What do lips do?
formed by Orbicularis muscle which closes the mouth
Fold of the mucous membrane called the labial frenulum that attaches the lips to the gingiva
What does the tongue do?
Made of skeletal muscle
Extrinsic muscles - attached to various bones such as the mandible and hyoid bone
Intrinsic muscles - change the shape and size of the tongue to assist with speech and swallowing
Held to the floor of the oral cavity by a fold of mucous membrane called the lingual frenulum (if too short - tongue tied or anklyoglossia)
On the dorsum (upper surface) of the tongue are many small projections called papillae (taste receptors and touch receptors)
Helps mix food and holds it between the teeth
Back of the tongue contains lymphatic tissue, called lingual tonsils, which destroy bacteria and viruses
What is the hard palate in the roof of the mouth?
Formed by the maxillary and palatine bones
Covered by a mucous membrane and stratified squamous epithelium
What is the soft palate in the roof of the mouth?
Posterior to the hard palate
Formed by muscle and is also covered by a mucous membrane
Separates the oral from the nasal cavity
What is the uvula?
Projecting off the posterior aspect of the soft palate
Prevents food and liquids from entering the nasal cavity during swallowing
What are the Lingual, palatine, and pharyngeal tonsils ?
protect the area from bacteria and viruses
Describe teeth
Incisors (most medial teeth), cut off food pieces
Cuspids (canines) are the sharpest teeth and they tear tough food
Premolars and molars are flatter, both are designed to grind food
Two sets of teeth
Primary or deciduous dentition (baby)
Secondary or permanent dentition (adult)
What are Salivary glands?
Secrete saliva, a mixture of water, enzymes, and mucus
Serous cells secrete a fluid made up mostly of water and also amylase
Mucous cells secrete mucus
Parotid, submandibular, and sublingual glands
What are serous cells?
cell in salivary gland
secrete a fluid made up mostly of water and also amylase
What are Mucous cells?
cell in salivary gland
secrete mucus
What is mass of mucous and serous cells?
Mass created by food mixed with the saliva and mucus mixture is called a bolus
What are parotid glands?
Salivary gland
largest ones
found under skin in front of ears
secrete serous saliva
What are submandibular glands?
Salivary gland
found on floor of mouth inside mandible
Secrete both serous and mucus
What are sublingual glands?
Salivary gland
smallest ones
under tongue
dry mouth - xerostomia
What is the Pharynx?
also known as the throat
Long, muscular structure
Extends from the area behind the nose to the esophagus
Connects the nasal cavity with the oral cavity for breathing through the nose
Composed of skeletal muscle
Lined with a mucous membrane
Pushes food into esophagus
What are the divisions of the pharynx?
Nasopharynx , behind the nasal cavity
Oropharynx , behind the oral cavity - part of both digestive and respiratory systems)
Laryngopharynx, behind the larynx- continues as the esophagus (part of both digestive and respiratory systems)
What is deglutition?
Swallowing - mostly a reflex
- Soft palate rises, causing the uvula to cover the opening between the nasal and the oral cavities
- Epiglottis covers the opening of the larynx
- Tongue presses against the roof of the mouth, forcing food into the oropharynx
- Muscles in the pharynx contract, forcing food toward the esophagus
- Esophagus opens
- Food is pushed into the esophagus by the muscles of the pharynx.
What is the esophagus?
Muscular tube that connects the pharynx to the stomach
Lies posterior to the trachea
Descends through the mediastinum in the thoracic cavity, through the diaphragm, and into the abdominal cavity
Opening in the diaphragm through which the esophagus passes is called the esophageal hiatus (where hernias occur)
1st section- skeletal muscle 2nd - mix of smooth and skeletal 3rd - smooth muscle
What is a hernia?
when organ pushes through a wall that contains it
What is Upper esophageal sphincter ?
Skeletal muscle and controls food entering the esophagus from the laryngopharynx
What is the Lower esophageal sphincter ?
Smooth muscle and controls food entering the stomach from the esophagus
What is Mucosa?
1st layer of GI tract
GI tract inner lining
Enzyme and mucus- secreting epithelial tissue
Very active in absorbing nutrients
What is submucosa?
2nd layer of GI tract
Areolar connective tissue, blood vessels, and a network of nerves called the submucosa plexus
Blood vessels that carry away absorbed nutrients
What is Muscularis?
3rd layer of GI tract
Smooth muscle, some areas also have skeletal muscle
Contracts to move materials through the canal
What is Serosa or peritoneum?
4th layer of GI tract
Outermost layer or adventita
Serous membrane with areolar connective tissue and simple squamous epithelium
Double-walled, outermost layer
Innermost wall is called the visceral peritoneum - keeps outside of SI moist
Outer layer is called the parietal peritoneum - abdominal lining
What is the stomach?
Below the diaphragm in the left upper quadrant of the abdominal cavity
Cardiac region-Attached to the esophagus (first portion)
Fundus-Superior to the cardiac region (2nd portion)
Does not absorb alot (only h2o, alcoholm fat soluble drugs) , the small intestine does the absorption
What is the pylorus?
Narrow portion connected to the small intestine
Pyloric sphincter controls the movement of substances from the pylorus of the stomach into the small intestine
What are rugae?
Numerous folds on the inner lining of the stomach
Help churn and mix the gastric contents
What are gastric glands?
Mucous cells secrete mucus to protect the lining of the stomach against the acidic pH.
Chief cells secrete pepsinogen, which is changed to pepsin in the presence of acid
Pepsip digests proteins .
What do parietal cells do?
Parietal cells secrete hydrochloric acid, which is necessary to convert pepsinogen to pepsin.
Secrete intrinsic factor, which is necessary for vitamin B 12 absorption
When a person smells food, the parasympathetic NS stimulates gastric glands
How are gastric glands stimulated?
by Gastrin produced by the stomach
What inhibits gastric glands?
Hormone cholecystokinin made by the small intestine
What is Chyme?
Mixture of food and gastric juices
Once chyme is well mixed, stomach contractions push small amounts into the small intestine a little at a time
4-8hours to empty stomach
Gastronomy tube can be put into stomach if you cant swallow - Ensure drink
What is the small intestine?
Carries out most of the digestion in the body
Responsible for absorbing most of the nutrients into the bloodstream
First section is called the duodenum - receives secretions from pancreas
Middle portion is called the jejunum - if tummy removed J tube put in for feeding
Third portion is called the ileum - longest
Joins the large intestine at the ileocecal valve
Mesentery
Holds the jejunum and ileum in the abdominal cavity
Mucosa
Enzyme and mucus- secreting epithelial tissue
Very active in absorbing nutrients
Submucosa
Blood vessels that carry away absorbed nutrients
What is churning?
Churning mixes the substances in the canal.
What are microvilli?
Found on the cells of the lining the small intestine
Fingerlike projections greatly increase the surface area
What enzymes are secreted by small intestine?
Peptidase, sucrase, maltase, lactase, and intestinal lipase
What digests sugar?
Sucrase, maltase, and lactase
Where does the small intestine end?
Ileocecal valve - control movement of Chyme from ileum to cecum
Describe part of Large intestine
produces vitamin K
Cecum- Beginning of the large intestine
Cecum gives rise to the ascending colon
Runs up the right side of the abdominal cavity
Vermiform appendix- Projects off the cecum
Contains lymphoid tissue and has a role in immunity
ascending colon-starts in Appendix in RUQ
Makes a turn toward the midline called the hepatic flexure
Becomes the transverse colon as it horizontally crosses the abdominal cavity
Descending colon-turns down from the spleen on LUQ
Begins at the splenic flexure
Forms the S-shaped tube called the sigmoid colon
What is sigmoid colon?
Forms the S-shaped tube connects to rectum
What are the functions of large intestine?
Absorb water
Produce certain vitamins
Form and expel the feces from the body
What is Gastritis?
Inflammation of stomach lining
Caused by bacteria or viruses, some medications, the use of alcohol, caffeine, spicy foods, excessive eating, poisons, and stress
Nausea, lack of appetite, heartburn, vomiting, and abdominal cramps
Avoid foods or medications that irritate the stomach lining, treatment with medications to reduce the production of stomach acids
What is Heartburn or Gastroesophageal Reflux Disease
When stomach acids are pushed into esophagus . If not treated GERD can cause erosion of esophagus
Alcohol, some foods, a defective cardiac sphincter, pregnancy, obesity, hiatal hernia, and repeated vomiting
Frequent burping, difficulty swallowing, pharyngitis, a burning sensation in the chest following meals and when lying down, nausea, and blood in the vomit
Losing weight, dietary changes, reducing alcohol intake, taking medications, and elevating the head and chest when lying down
What are Hiatal Hernias ?
Portion of the stomach protrudes into the thoracic cavity through the diaphragm
Obesity and smoking are considered risk factors
Excessive burping, difficulty swallowing, chest pain, and heartburn
Weight reduction, medications to reduce the production of stomach acid, and surgical repair of the hernia
What is stomach cancer
occurs mostly in uppermost portion - cardiac
Organism Helicobacter pylori has been implicated as well as polyps, some types of atrophic gastritis, and diets high in salt or nitrates.
Frequent bloating, loss of appetite, early satiety, nausea, vomiting, abdominal cramps, excessive gas, and blood in the feces
Radiation therapy, chemotherapy, and surgical removal of the tumor
What are Gastric or Stomach Ulcers
When lining of stomach breaks down
Caused by bacteria such as Helicobacter pylori, smoking, alcohol, excessive aspirin use, and hypersecretion of stomach acid
Nausea, abdominal pain, vomiting, and weight loss
Antibiotics, medications to reduce stomach acid production, surgery to remove the affected portion of the stomach, and a vagotomy
What is Crohns ?
Type of inflammatory bowel disease. Terminal ileitis
Evidence suggests a genetic component and an autoimmune component.
Abdominal pain and diarrhea, rectal bleeding, weight loss due to malnutrition, joint pain, skin problems, and febrile episodes
Change the patient’s diet, medications to reduce inflammation, and bowel rest where intravenous feedings are given so the patient’s digestive system is not used and so “rests
What is diarrhea?
Watery poops
Caused by bacterial, viral, or parasitic infections; ingestion of toxins; food allergies; ulcers; Crohn’s disease; laxative use; antibiotics; chemotherapy; and radiation therapy
Abdominal cramps, watery feces, and the frequent passage of feces
Drink clear fluids to prevent dehydration and antidiarrheal medications
What is colitis ?
Inflammation of large intestine
Caused by a viral or bacterial infection or the use of antibiotics
Abdominal pain, bloating, and diarrhea
In advanced cases, surgery to remove the affected area of the colon, known as a colectomy, may be recommended.
If too much of the colon is affected, a colostomy may be performed.
What is Colorectal Cancer ?
Arises from lining of rectum or colon
Over 60 years of age, a first-degree relative who had colorectal cancer, certain ethnicities, diet high in fat and low in fiber, as well as smoking and alcohol
Anemia, unintended weight loss, abdominal pain, blood in the feces, narrow “pencil-like” feces, or changes in bowel habits
Chemotherapy, and surgery to remove a cancerous tumor
What is constipation?
hard to poop
Causes are a lack of physical activity, lack of adequate fiber and water in the diet, use of certain medications
Infrequent bowel movements, bloating, abdominal pain and pain during bowel movements, hard feces, and blood on the surface of feces
Increase in dietary fiber, adequate fluid intake, regular exercise, and the use of stool softeners, laxatives, and enemas
What is Diverticulitis ?
Inflammation of the diverticuli in the intestine
Causes are mostly unknown.
Fever, nausea, abdominal pain, constipation or diarrhea, blood in the feces, and a high white blood cell count
Diet high in fiber, antibiotics, and keeping a food diary to track foods that cause flare-ups
Peanuts and seeds aggravate it
What are Inguinal Hernias ?
when Large intestine protudes into the inguinal canal
Caused by weak muscles in the abdominal walls
Lump in the groin or scrotum, or pain in the groin area that gets worse when bending or straining
Pain medications and surgery to repair the hernia
What is Appendicitis?
Caused by blockage of the appendix with feces or tumor, infection, or other idiopathic cause
Lack of appetite, pain in the right lower quadrant, nausea, slight fever, and an increased white blood cell count
Antibiotics to prevent infection and appendectomy
What are hemorrhoids?
Varicose veins of rectum or anus
Caused by constipation, excessive straining during bowel movements, liver disease, pregnancy, and obesity
Itching of the anal area, painful bowel movements, bright red blood on feces, and varicosities that protrude from the anus
Eating a high-fiber diet and drinking adequate water, stool softeners, medications to reduce the inflammation, and surgical removal
Describe the pancreas
Accessory organ - behind the stomach
Head, a body, and a tail
Endocrine and exocrine in function
Only 1 percent of the pancreas is endocrine and 99percent is exocrine
Exocrine function
Pancreatic acinar cells that produce pancreatic juice
Ultimately flows through the pancreatic duct to the duodenum
What does the pancreatic juice contain
Secretes juices into duodenum.
Contains
pancreatic amylase-mylase digests carbs. Salivary amylase is inactivated by stomach acids thats why the pancreatic one is needed
pancreatic lipase -digests lipids
pancreatic nucleases - digests nucleic acids
pancreatic trypsin, chymotrypsin, and carboxypeptidase - digests proteins
bicarbonate ions - to neutralize acids
What system is the pancreas part of ? Para or sympa?
Parasympathetic nervous system
Causes the pancreas to secrete bicarbonate ions into the duodenum which neutralize the acidicchyme arriving from the stomach
Where do secretin and cholecystokinin come from?
Come from the small intestine and stimulate the pancreas to release digestive enzymes
Describe the liver
Largest visceral organ in the body
URQ
Enclosed by a tough fibrous capsule
Capsule divides the liver into a large right lobe and a smaller left lobe by a fold of mesentery called the falciform ligament
Each lobe is separated into smaller divisions called hepatic lobules
Branches of the hepatic portal vein carry blood from the digestive organs to the hepatic lobules
What do the lobules in the liver contain?
Each lobule contains many cells called hepatocytes.
Hepatocytes process the nutrients in blood and make bile, which is used in the emulsification of fats.
Bile leaves the liver through the hepatic duct.
Hepatic duct merges with the cystic duct to form the common bile duct
Delivers bile to the duodenum
What are the functions of the liver?
Carbohydrate, lipid, and protein metabolism
Storage of excess glucose as glycogen, triglycerides, as well as vitamins A, B 12, D, E, and K
Synthesis of cholesterol and bile
Produces many proteins, including albumin and fibrinogen
Metabolizes and detoxifies many substances
Kupffer cells, phagocytize red and white blood cells and bacteria
Describe the gall bladder
accessory organ - pear shaped
Its function is to store bile.
Bile leaves through the cystic duct.
Salts in bile emulsify large fat globules into smaller ones.
Bile salts also increase the absorption of fatty acids, cholesterol, and fat-soluble vitamins into the bloodstream.
What is the gastric phase of digestion
Neural and hormonal control
-Regulation of neural and hormonal control
Stretch and chemical receptors in the stomach activate the parasympathetic system to increase gastric secretions and increase peristalsis and emptying of the stomach
What is the Intestinal phase of digestion?
Neural and hormonal regulation
It inhibits gastric emptying to allow the small intestine time to absorb the nutrients that enter it
What is the Cephalic phase of digestion?
starts in the cerebral cortex
Thought, sight, or smell of food as well as the taste of food can activate the cerebral cortex, hypothalamus, and brain stem
Cranial nerve VII, the facial nerve, and cranial nerve IX, the glossopharyngeal nerve, stimulate the secretion of saliva
Cranial nerve X, the vagus nerve, stimulates the stomach to secrete gastric juices
What is Pancreatic Cancer?
4th leading cause of cancer
Risk factors include smoking, alcohol consumption, increased age, race, being male, and a history of pancreatitis
Depression, fatigue, lack of appetite, nausea or vomiting, abdominal pain, constipation or diarrhea, jaundice, and unintended weight loss
Radiation therapy, chemotherapy, and surgical removal of the tumor
What is Hepatitis?
liver inflammation
Two major causes of hepatitis are alcohol and viruses
Other causes include bacteria, parasites, immune disorders, and an overdose of acetaminophen
Mild fever, bloating, lack of appetite, nausea, vomiting, abdominal pain, weakness, and jaundice, the itching of various body parts, an enlarged liver, dark urine, and gynecomastia- boobs in males
What is Cirrhosis?
chronic liver disease when liver tissue is replaced with nonfunctional scar tissue
Chronic alcoholism is the primary cause
Other causes include hepatitis B and C infections, certain immune disorders, and exposure to toxic metals
Anemia, fatigue, mental confusion, fever, vomiting, blood in the vomit, hepatomegaly, jaundice, unintended weight loss, edema, ascites, abdominal pain, decreased urine output, and pale feces
Alcohol consumption should be discontinued
Liver transplant
What is Cholelithiasis?
gall stones, types - cholesterol and pigment stones
Causes of gallstone formation may be due to too much cholesterol in the bile, too much bilirubin in the bile, or inadequate emptying of the gallbladder
Asymptomatic or may have terrible pain in the abdomen if the gallstones become lodged in a duct
Cholecystecomy is the most common treatment, but medications may be used
What are LDLs?
VLDLs are converted to LDLs
Made up of the same four substances as VLDLs
Have a higher percentage of proteins and cholesterol
Cholesterol in LDLs is considered “bad” cholesterol
Deposited in arteries and is responsible for arteriosclerosis
What are VLDLs?
Consist of proteins, triglycerides, phospholipids, and cholesterol
Made in the liver
Transport triglycerides to adipose tissue for storage
What are HDLs?
Have the highest percentage of proteins
HDLs transport cholesterol to the liver for elimination
Considered “good” cholesterol
What a cholesterol and its limit?
Cholesterol
Obtained from the foods we eat and from synthesis by the liver
Total cholesterol in an adult should be less than 200 mg/dL of blood
LDL cholesterol less than 130 mg/dL
HDL at least 40 mg/dL
Why are lipids important?
Lipids are essential for life.
Necessary for cell membranes
Hormone production
Blood clotting
Myelin production
Excess lipids are stored in adipose tissue.
Helps cushion organs and hold them in place, and acts as an insulator
Hypercholesterolemia
Cause may be dietary, but more often there is a genetic component
Cholesterol deposited around the eyelids, the iris of the eye, tendons of the hands, elbows, knees, and feet
Condition puts individuals at risk for heart disease
Diet low in fat, statins, and bile acid sequestrants
What is catabolism?
As proteins are broken down, amino acids may be recycled or converted into glucose or lipids, or used to synthesize ATP.
Breaking down larger molecules into smaller molecules
Give off more energy than they consume
What is anabolism?
Anabolism of amino acids involves the formation of new chemical bonds
Anabolic reactions
Synthesis of substances
Require energy
What is Basal metabolic rate (BMR
Amount of energy being used in a resting state
Determined by measuring the amount of oxygen used per kilocalorie of food utilized
How does body temperature affect you?
Allows the body to maintain a stable body temperature of 37°C
Hormones and the nervous system affect body temperature.
Heat is lost from the body through evaporation, conduction, radiation, and convection.
Hypothalamus is the control center for temperature regulation
What is needed for a balanced diet ?
One gram of protein or carbohydrate provides 4.1 calories of energy, whereas 1 gram of lipid produces 9.5 calories
Vitamin D
Essential for the absorption of calcium and phosphorus from the GI tract
Vitamin A
Fat soluble Essential for epithelial cells, acts as an antioxidant, participates in the formation of photoreceptors in the eye, and helps with bone and tooth development
Vitamin K
Fat soluble -Involved in blood clotting
Vitamin E
Fat soluble -Antioxidant and also participates in the formation of red blood cells, DNA, and RNA
Involved in normal functioning of the nervous system
Vitamin C
Fat soluble - Antioxidant and is involved in wound healing, is important for the synthesis of collagen, and acts as a coenzyme in many reactions
Folic Acid
Water soluble - Important for many enzyme systems and the development of the nervous system
Vitamin B2(riboflavin)
Water soluble - Coenzyme in metabolic reactions and carbohydrate and protein metabolism
Niacin
Water soluble - Essential in many metabolic reactions
Vitamin B6(pyridoxine)
Water soluble - Important coenzyme
Vitamin B12(cobalamin)
Water soluble - Coenzyme in the Krebs cycle and red blood cell formation
Calcium
Most abundant mineral in the body
Nerve transmission, muscle activity, blood clotting, and cellular activity
Phosphorus
Metabolic reactions, buffering blood pH, part of DNA and RNA, and production of ATP
Potassium
Most abundant cation in the extracellular fluid
Generation of nerve impulses
Sulfur
Production of ATP and is part of several hormones and vitamins
Sodium
Generation of action potentials and helps in water regulation
Chloride
Necessary for digestion, buffering blood pH, and water balance in the body
Iron
Trace - Component of hemoglobin
Iodide
Trace -Synthesis of thyroid hormones
Cobalt
Trace -Component of vitamin B12
Chromium
Trace -Helps with insulin activity
Copper
Trace -Coenzyme in several metabolic reactions
Fluoride
Trace -Component of bone and teeth
Magnesium
Coenzyme and is required for the functioning of muscle and nervous tissue
Zinc
Trace -Sensation of taste, wound healing, and various metabolic reactions
Manganese
Trace -Metabolic reactions
Selenium
Trace -Antioxidant
What is Kwashiorkor?
Too little protein in the diet
Common disorder seen in Africa where there may be sufficient calories in the diet but there is inadequate protein
Ascites, hepatomegaly, hypotension, and delayed mental and physical development
What is Marasmus?
Both protein and calorie insufficiency
Emaciation, muscle wasting, delayed growth, and death
Tests
- Amylase
- Bilirubin
- Carcinoembryonic antigen (CEA)
- Carotene
- Cholesterol/Triglycerides
- CBC
- Glucose
- Lipase
- Occult blood
- Ova and Parasite
- Hgb A1C
what gene mutation causes cystic fibrosis
cftr
what organs are on the left side of the body
heart, stomach, left kidney and spleen
extra glucose is converted into
glycerol and fatty acids
metabolic syndrome
hese conditions include increased blood pressure, high blood sugar, excess body fat around the waist, and abnormal cholesterol or triglyceride levels.
