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USMLE
GI Phys
Question | Answer |
---|---|
source of gastrin | G cells in antrum of stomach |
source of CCK | I cells in duo and jejunum |
source of secretin | s cells, duodenum |
action of gastrin | increased H+ in stomach increased growth of gatric mucosa increased gastric motility |
action of CCK | increases pancreatic secretions increases gallbladder contraction slows gastric emptying |
action of secretin | release of HCO3- decreased gastric acid secretion |
regulation of gastrin | decreased when stomach pH <1.5 increased when stomach is distended, presence of AA and peptides increased in vagal stimulation |
regulation of CCK | decreased if stomach pH<1.5 decreased by secretin increased by fatty acids and AA |
regulation of secretin | increased by acid, FA in lumen of duo |
source of somatostatin | D cells of pancreatic islets and GI mucosa |
what regulates somatostatin | increased by acid decreased by vagal stimulation |
what is somatostatin used to treat | VIPoma carcinoid tumors |
what releases GIP? | K cells in duo and jejunum |
what does GIP do? | exocrine fxn of decreasing H secretion endocrine fxn of increasing insulin release |
regulation of GIP | increased by fatty acids, AA, oral glucose |
which is used more rapidly: oral or IV glucose? | oral |
source of VIP | parasympathetic ganglia in sphincters, gallbladder and small intestines |
action of VIP | increases intestinal water absorption relaxation of intestinal smooth muscle and sphincters |
regulation of VIP | increased by distention and vagal stimulation decreased by adrenergic imput |
what is VIPoma | non-alpha, non-beta islet cell pancreatic tumor that secrete VIP --> copious watery diarrhea |
action of NO on GI tract | increased smooth muscle relaxation, (NB: lower P in LES) |
what is implicated in decreased NO secretion | accounts for incresed LES tone seen in achalasia |
where is HCO3- released from? | mucosal cells stomach duo |
where is pepsin released from? | chief cells of stomach |
what controls gastric acid release | increased by histamine and ACh decreased by somatostatin, GIP, PG, secretin |
fxn of salivary amylase | hydrolyzes alpha-1,4 linkages --> disaccharides |
fxn of pancreatic amylase | hydrolyzes starch to oligosaccharides and disaccharides |
where is pancreatic amylase found | highest [] in duo lumen |
fxn of oligosaccharide hydrolase | hydrolyzes oligosaccharidses --> monosaccharides RL step in carb digestion |