GI ML: 5 Flashcards
What is the largest portion of the GI tract
small intestine
Where does the small intestine begin
pyloric sphincter
Where does the small intestine end
ileocecal sphincter
What are the three parts of the small intestine
duodenum
jejunum
ileum
What are the four things that increase SA
coilled length
circular folds
Villi
Micovilli
where does digestion and absorption occur
microvilli
- where nutrient moves from GI lumen into epithelial cells
What are the secretions of the small intestine
1500ml of water, mucus, and NaCl
500ml of bile
1500ml of pancreatic secretins
Where do the liver and pacreas connect to small intestine
duodenum
What are the two exocrine parts of the pancreas and what do they secrete
acinar cells= pancreatic enzymes
duct cells= bicarb
What are the pancreatic enzymes
trypsin, chymotrypsin, elastase
carboxypeptidase
lipase
amylase
ribonuclease, deocyribonuclease
What is the substrate for trypsin, chymotrypsin, elastase
proteins- break peptide bonds to form peptide fragments
What is the substrate for carboxypeptidase
proteins- splits off terminal amino acid from carboxyl end of protein
What is the substarte for lipase
triglycerides- splits off two fatty acids from triglcuerides forming free fatty acids
What is the substarte for amylase
polysacchardies- into maltose
What are bile salts made from and what is their job
made from cholestrol and emulsify fats
Where are bile salts reabsorbed
distal ileum
-mostly reaborbed
What feeds into the hepatic portal vein
capillaries from stomach, pancreas, small I, large I
Once in vein what happens
nutrients are sent to liver for processing and then go through inferior vena cava to be put back into circulation
What is motiliaty #1 in the small intestine
segmentation- alternating contration and relaxation at each location
Where is contraction the fastest and slowest
duodenum and ileum
What is segmentation mediated by
both short and long reflexes
What does the segmentation do
mizes chyme with enzymes and bicarb to ensure more exposure of enzymes and neutralization of acid
What is the second motility of the small intestine
MMC-migrating myoelectric complex
When does MMC occur
after a meal during the post absorptive phase
What is MMC
short distance peristaltic wave clears any remaining materials from intestine
