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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 |