The Gastrointestinal System Flashcards
____ is the chemical and mechanical breakdown of foods into smaller compounds that can be utilized by the body.
Digestion
The gastrointestinal system consists of the organs of the ____, the pathway through the body that food travels while being digested and absorbed, as well as the accessory organs that release secretions necessary for digestion to occur.
alimentary canal
The ____ release digestive enzymes that mix with the food to begin chemical digestion and lubricate the mouth.
salivary glands
Swallowing is triggered when the chewed food, the ____, is sensed by the ____.
bolus; pharynx
The bolus passes through to the ____ and then into the stomach aided by ____, a wavelike contraction of smooth muscle that moves digested material along the digestive tract.
esophagus; peristalsis
Both chemical and mechanical digestion continue in the ____, a hollow organ separated from the esophagus by the ____ and from the small intestine by the ____.
stomach; esophageal sphincter; pyloric sphincter
The pH of the stomach is maintained between 1 and 2 by the release of ____, which contains hydrochloric acid (HCI) as well as enzymes that begin the chemical digestion of protein.
gastric juice
The contents of the stomach, now called ____, exit the stomach and enter the ____, where digestion is completed and reabsorption begins.
chyme; small intestine
What are the 3 sections of the small intestine?
duodenum; jejunum; ileum
When chyme enters the intestine, it signals the pancreas and gallbladder to release their digestive enzymes into the ____, the first part of the small intestine.
dudoenum
____, created in the liver and stored in the gallbladder, is secreted into the duodenum through the ____.
bile; common bile duct
The digestion of protein, carbohydrates, and fats occurs in the ____.
duodenum
The small intestine is lined with ____ and ____, finger-like folds in the lining of the intestine that increase surface area to aid absorption.
villi; microvilli
Approximately 90% of all nutrients will be absorbed in the ____, with the exception of Vitamin B12, which is only absorbed in the ____.
jejunum; ileum
The digested material passes from the ilium through the ____, the pouch at the beginning of the intestine, into the large intestine.
cecum
Water, salts, and vitamin K are absorbed in the ____, the proximal part of the large intestine.
colon
Any remaining waste collects in the ____, the terminal section of the large intestine, to be expelled from the body through the ___, regulated by the action of the ____.
rectum; anus; anal sphincter
____ involves enzymes or acids that break down food at the molecular level. Digestive enzymes are secreted by certain exocrine organs – including the pancreas, liver, and salivary glands – and by specialized cells in the lining of the stomach and intestines.
chemical digestion
____ involves the physical breakdown of food into smaller pieces. Chewing, the churning process of the stomach, and the muscular action of peristalsis physically mash food particles apart, creating a greater surface area for chemical digestion to take place.
mechanical digestion
So they do not digest the cells that synthesize them, enzymes are released in the inactive ____ form and are are rendered active only in the presence of other digestive compounds, such as HCI.
zymogen
Enzymes that function best in acidic environments (low pH) are most active in the ____; enzymes that function best in alkaline environments (high pH) are most active in the ____.
stomach; small intestine
____ lubricates the mouth; contains salivary amylase, which breaks down carbohydrates and starches; contains salivary lipase, which breaks down fats.
Saliva salivary glands (mouth)
____ digests protein by breaking bonds of amino acids.
Pepsin(ogen) chief cells (stomach)
____ sterilizes potentially harmful bacteria; causes proteins to denature; converts pepsinogen to pepsin.
Hydrochloric acid (HCI) parietal cells (stomach)
____ helps neutralize the acidic chyme as it enters the small intestine; aids in fat digestion and absorption by emulsifyng lipid particles.
bile
liver
____ neutralizes chyme as it enters the duodenum.
pancreatic bicarbonate
pancreas
____ maintains the mucosal lining of the stomach; protects the stomach walls from the digestive activity of HCI and other gastric enzymes.
mucus Goblet cells (stomach)
____ digests lipids and fats in the small intestine.
pancreatic lipase
pancreas
____ includes lactase and other disaccharidases that breaks down lactose and other simple sugars; nucleases that break down nucleic acids; and peptidases that complete protein digestion and convert trypsinogen to trypsin.
brush border enzymes
microvilli (small intestine)
____ digests proteins in the small intestine.
trypsin(ogen) (proteases)
pancreas and small intestine
Absorption begins in the villi of the small intestine. Most nutrients absorbed in the small intestine move into the capillaries. The capillary network of the digestive tract carries blood to the liver through the ____. Digested fats are absorbed into the lymphatic system.
hepatic portal vein
The hormone ____ stimulates gastric acid and mucosal secretion; increases motility.
gastrin
The hormone ___ stimulates gallbladder to release bile; stimulates the pancreas to release pancreatic enzymes; inhibits gastric emptying and acid secretion.
CCK (cholecystokinin)
The hormone ____ stimulates pancreas to release bicarbonate; inhibits gastric emptying; increases bile secretion.
secretin
The hormone ____ induces hunger.
ghrelin
The hormone ____ reduces hunger by signaling satiety.
leptin
The hormone ____ inhibits gastric secretion and slows digestion.
somatostatin
The hormone ____ inhibits gastric secretion and slows digestion.
somatostatin
The hormone ____ stimulates uptake of glucose for conversion into glycogen; decreases blood glucose levels.
insulin
The hormone ____ initiates breakdown of glycogen; increases blood glucose levels.
glucagon
The hormone ____ initiates breakdown of glycogen; increases blood glucose levels.
glucagon
