Module 8: Gastrointestinal Tract Flashcards
functions of the digestive system
digestion
secretion
absorption
motility
structure of the GI tract wall
mucosa
submucosa
muscular externa
serosa (outermost)
circular folds, villi, microvilli -> increase surface area for absorption
HCI secretion
gastrin (hormone) +
acetylcholine (neurotransmitter) +
histamine (paracrine) +
somatostatin (paracrine) -
amount of fluid ingested by a person per day
1200ml
amount of fluid secreted into the GI tract per day
7000ml
amount of fluid excreted in the feces per day
100ml
most of the fluid that enters the GI tract by ingestion or secretion is
absorbed
net movement of Na+ from lumen to interstitial fluid and water follows by osmosis
absorption
secretes many digestive enzymes
secretes fluid rich in bicarbonate to neutralize stomach acid, which would inactivate the enzymes
pancreas
synthesizes and secretes bile salts, which are needed for fat digestion
secretes bicarbonate
liver
temporarily stores the undigested material
concentrates it by absorbing salt and water
when the rectum contracts, feces are expelled (defecation)
large intestine
stores and concentrates bile from the liver between meals
contracts and releases bile into the small intestine
small sac under liver
gallbladder
amphipathic
cholesterol derivatives for the emulsification of hydrophobic fats
to keep fatty acids and
monoglycerides in solution until
they are absorbed into the
epithelial cells, they are held as ________ and then released
micelles
