Module 3 - Digestive System Flashcards
What are the two main divisions of the digestive system?
1) The alimentary canal (AKA gastrointestinal tract)
2) The accessory organs
Describe the alimentary canal.
It is a continuous muscular tube starting at the mouth and ending at the anus. The parts are the mouth, pharynx, esophagus, stomach, small intestine, large intestine and anus.
What are the accessory digestive organs?
Teeth, tongue, salivary glands, pancreas, liver and gall bladder.
What does heterotrophic mean?
Heterotrophic means you must take in food and digest it- you cannot produce your own nutrients like plants do.
What is an omnivore?
An omnivore is an animal that eats both plants and animals.
Describe the structures of the mouth.
The opening of the oral cavity is the lips. The superior surface is the hard and soft palates. The inferior surface is the tongue. The posterior border of the superior surface is the uvula. The cheeks form the lateral borders.
What is the lingual frenulum?
The vertical mucous membrane that extends from the inferior surface of the tongue to the floor of the mouth.
What is mastication?
The process of chewing food.
What enzyme does saliva contain?
Amylase
The upper jaw is called the ______________.
The lower jaw is the _______________.
Maxilla
Mandible
Describe the structure of the tongue.
The tongue is a muscle that fills the mouth and moves food in the processes of chewing and swallowing. It attaches to the mandible and the hyoid bones. The superior surface is covered with 3 kinds of papillae: circumvallate, fungiform and filiform. Circumvallate and fungiform papillae both contain taste buds.
Where are taste buds located?
The wall of the mouth, surface of the oropharynx, and in the circumvallate and fungiform papillae of the tongue.
The pharynx is lined with two lavers of _________ that alternate to push food down the alimentary canal. The outer layer is ____________, and the inner layer is ______________.
Muscle
Circumferential, logitudinal.
What prevents food from entering the laynx?
The epiglottis.
The part of the alimentary canal that goes from the pharynx to the stomach is the ______________.
Esophagus
What are the four layers of the tissue that forms the esophagus through the large intestine?
1) Mucosa: secretes mucus into the interior of the gastrointestinal tract.
2) Submucosa :contains blood and lymph vessels, lymph nodes, nerves, and mucous glands.
3) Muscularis externa: two layers of muscle, the outer longitudinal fibers and inner circumferential fibers. The exception to this is the stomach, which has a third layer of muscle called the oblique layer.
4) Serosa: cells that make serous fluid.
What is the esophageal hiatus?
The esophageal hiatus is the hole in the diaphragm that the esophagus goes through.
Name the seven sphincters of the digestive tract.
The upper esophageal sphincter, The lower esophageal sphincter (a.k.a. cardiac sphincter or gastroesophageal sphincter), the pyloric sphincter, the sphincter of Oddi, the illeocecal sphincter, the inner anal sphincter and the external anal spincter.
What are the two curves in the stomach called?
The lesser curvature is the smaller interior curve, the greater curvature is the larger curve.
Define peristalsis.
The process of moving food along the alimentary canal via waves of muscular action.
Describe the peritoneum of the stomach.
The peritoneum stretched between the liver and the lesser curvature is called the lesser omentum. The peritoneum thatattaches to the greater curvature is called the greater omentum. It is a pocket of peritoneum tha hangs down over the small intestine and returns to the stomach. The transverse colon is inside the pocket. The greater omentum contains fat deposits and collections of macrophages.
What are the four regions of the stomach?
Cardiac
Fundus
Body
Pylorus
The folds of the stomach wall are called ______________.
Rugae
What is a gastric ulcer?
It is an open sore in the stomach, caused by Heliobacter Pylori, or by NSAID use.
After food is mixed with gastric juices in the stomach, it is called _________.
Chyme
The small intestine starts at the _____________ and runs to the _______________. Its three parts are the ____________, ______________, and the _____________.
Pyloric valve, ileocecal valve
duodenum, jejunum, ileum
What processes of chemical digestion occur in the duodenum?
Bile and pancreatic enzymes are introduced from the ampulla of Vater. The duodenum also has Brunner’s glands, or duodenal glands, that release bicarbonate to raise the pH of the chyme and prevent it from burning the mucosa.
Describe circular folds.
Circular folds begin in the proximal end of the duodenum and continue until the middle of the ileum. They are folds of tissue that cause the chyme to spiral in its progression down the tract, allowing for intestinal excretions to mix thoroughly with the chyme, and so that the nutrients in the chyme come into contact with the villi for absorption.
Describe the villi of the small intestine.
Intestinal villi are small fingers of tissue, each with its own blood and lymph supply, that increase the surface area of the intestinal mucosa to allow for absorbtion of nutrients.
Enzymes made by the small intestine remain ____________ to the intestinal cells.
Attached
__________________ and _______________ enter the blood stream in the villi. ________________ and _____________ enter the lymph through individual lymphatic vessels in the villi called ______________.
Carbohydrates, amino acids
Fatty acids, other lipid soluble compounds like glycerol
lacteals
The large intestine, or colon, begins at the _________ and ends at the __________. List the 8 parts of the colon.
ileocecal sphincter, exterior anal sphincter
cecum, appendix, ascending colon, transverse colon, decending colon, sigmoid colon, rectum, anal canal
The major functions of the large intestine are:
To collect water from the chyme, absorb vitamins from the bacteria that are present here, and expell waste.
What is the rectum?
The last 20 cm of the intestine, ending in the anus.
What does the pancreas secrete into the duodenum?
Bicarbonate, amylase, tripsin, lipase and other enzymes.
What are the three digestive functions of the liver.
1) to produce bile.
2) to control glycogen production and release
3) to produce urea from excess protein
What is bile?
Bile is a green substance produced by the liver and stored in the gall bladder. Its color comes from broken down hemoglobin. It also contains bile salts, which emulsify fats in our food.
What are the four functions of the digestive system?
ingestion, digestion, absorption, and excretion
Digestion occurs through both ____________ and ____________ processes.
Mechanical, chemical
Describe the beginning steps in digestion.
You sense and think about the food. This starts the production of saliva, gastrin and stomach acid. You chew to break up the food and increase its surface area. You taste it, (sweet, bitter, salty, sour, umami) and salivary glands secrete salivary amylase to break down starches, lingual lipase to break down fats, and mucous to lubricate the bolus on its way down. Little to no absorption occurs here.
Describe what happens in the digestive process between the mouth and the Stomach.
As we swallow, the soft palette closes off the nasal cavity and the epiglottis closes off the the trachea so that food travels down the esophagus. The nervous system signals the muscles in the esophagus to contract and begin peristalsis, which pushes the food down and through the esophageal (or cardiac) sphincter. This sphincter serves to keep the acidic stomach contents in the stomach and away from the delicate esophageal lining. Very little absorption occurs here.
Describe the digestive processes that occur in the stomach?
Food enters the stomach through the cardiac/esophageal sphincter. It can accommodate about 4 cups of food, and holds it for 2 or3 hours. The food undergoes both physical and chemical changes. The muscles around the stomach stir and squeeze the food to mix the digestive juices in. The parietal cells produce hydrochloric acid, and chief cells produce pepsinogen. The HCL breaks the food down and turns pepsinogen into pepsin, which is an enzyme that breaks down proteins. It also halts the action of amylase. The walls of the stomach also excrete gastrin, gastric lipase, intrinsic factor, hormones and mucous.
The food and these secretions mix to form chyme. Very little absorption occurs here. The pyloric valve holds the contents in the stomach until it’s time for food to move on.
What are the function of hormones in the stomach?
To regulate hunger and acid secretion.
Describe the digestive processes that occur in the small intestine.
Chyme leaves the stomach through the pyloric valve and enters the duodenum. This triggers a reflex that closes the pyloric sphincter, and also the release of the hormones cholecystokinen and secretin. These both cause the pancreas to release juices, while the cholecystokinin acts on the gallbladder to release bile, and the secretin causes the liver to create bile. Digestive juices enter from the Ampulla of Vater through the sphincter of Oddi, and serve to raise the pH of the chyme with bicarbonate and emulsify fats through the addition of bile. Amylase, tripsin, and lipase from the pancreas further break down the food. The food is reduced to its chemical parts. Peptides, which result from the first step in protein digestion, are converted by peptidases to amino acids. Maltose, which results from the first step in starch digestion, is converted by maltase to glucose. Other disaccharides, each of which is acted upon by a specific enzyme, are digested in the small intestine. Food moves through the small intestine and nutrients are absorbed through the villi and enter the lymph and blood.
How does the body regulate hunger?
Through hormones and the nervous system. The hypothalamus has chemical receptors that monitor nutrient levels and turn hunger on, or signal satiety. Hormones such as ghrelin, endorphines and neuropeptide-y all signal hunger. Leptin, serotonin and cholecystokinin all signal satiety. Ghrelin is made by thte stomach and signals hunger to the brain. Leptin is made by fat cells and signals satiety.
Define bolus.
A wad of food that is swallowed.
What are the six classes of nutrients?
Carbohydrates, Fats, Proteins, Vitamins, Minerals, Water
Categorize the six classes of nutrients as micro- or macronutrients, as organic or inorganic compounds, and list which of the three functions they perform.
1) Carbohydrates are organic macronutrients that provide energy. 2) Proteins are organic macronutrients that can be used to make energy, build tissue and regulate processes. 3) Fats are organic macronutrients that can be used to make energy, build tissue and regulate processes. 4) Vitamins are organic micronutrients that perform regulation. 5) Minerals are inorganic micronutrients generally (16 of them are macronutrients) that are used for building tissues and to regulate processes. 6) Water is an inorganic macronutrient that can build tissues or regulate processes.
The three types of lipids discussed here are _____________, found in animal fats, ___________ found in nuts and seeds, and ____________ which our body makes, but are also found in animal food products.
saturated fats, unsaturated fats, cholesterol
___________ __________ _____________ are proteins that our body can not create and therefore must be consumed. There are __ of these for infants and __ for adults. If a food source contains all __, it is called a _________ protein. Otherwise it is an __________ protein.
Essential amino acids
10
9
9
complete, incomplete
Vitamins are __________ __________ ___________. They are either ______ or ________ soluble. An excess of ______ soluble vitamins can cause a problem because the excess is stored instead of eliminated.
essential organic micronutrients
water
fat
fat
__________ are nonorganic nutrients needed by the body.
Minerals
The process of using metabolism to build bigger molecules from smaller ones is ____________. The process of breaking molecules apart is _____________.
Anabolism
Catabolism
What is cellular respiration?
The process of cells creating ATP
Cellular respiration is either _________ or __________. If it happens in the presence of oxygen it is ___________.
Aerobic or anaerobic.
Aerobic
Describe cellular respiration.
During cellular respiration, glucose combines with oxygen to form carbon dioxide, water, and ATP.
How is the energy released from the breakdown of glucose used by the body?
The energy is released during the breakdown of glucose is used by the body to add a phosphate to an adenosine diphosphate (ADP) molecule and make adenosine triphosphate (ATP).
Describe glycolysis.
In glycolysis glucose is broken down into two pyruvic acid molecules and two ATP molecules are formed.
Describe the citric acid cycle (TCA cycle).
In the citric acid (TCA) cycle the pyruvic acid product of glycolysis is converted to carbon dioxide forming some additional ATP.
Describe the electron transport chain.
In the electron transport chain hydrogen atoms formed during glycolysis and the TCA cycle are converted to water releasing energy which is used to add phosphate to ADP to form ATP.
Lipid metabolism yields _______ the energy formed during glucose metabolism.
twice
Name, tell the location of and explain in detail the first stage of lipid metabolism.
Lipid metabolism occurs in the liver by a process known as beta-oxidation to form acetic acid which is further catabolized by the TCA cycle to carbon dioxide forming some ATP.
What does HCl do in the stomach?
It kills germs, breaks down food, deactivates salivary amylase, and turns pepsinogen in to pepsin.
What are the 7 minerals we use in the largest amounts?
Calcium, magnesium, potassium, sulfur, chloride, sodium, phosphorus
