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Phys GI 2
Duke PA Physiology
Question | Answer |
---|---|
What phase is regulated by gastrin and histamine? | Gastric phase |
Where does the gastrin bind? | Gastric receptors on parietal cells |
What does gastrin cause? | activates proton pump |
What does histamine cause? | paracrine secretion (regulated by gastrin) turns on proton pump |
When does the gastric phase occur? | when food enters the stomach |
What happens to gastrin in the intestinal phase? | decreases - secretin provides negative feedback for gastrin |
What phase does the majority of acid output occur? | gastric phase |
Where does secretin come from? | duodenum |
What stimulates secretin release? | acid production |
What innervates cephalic phase? | vagal innervation |
What do tums do? | decrease pH by neutralizing acid in stomach - bicarb - immediate relief, titrates acid |
What does tagamet do? | hits the histamine receptors, decreases HCl production |
What do nexium and prilosec do? | knocks off the proton pump - stops acid production |
What is the drug of choice for excess acid production in stomach? | nexium or prilosec |
What are the consequences of nexium or prilosec? | loses protective function of acid against bacteria, cuts off negative feedback loop and increases gastrin levels, interferes with secretin |
What shuts off gastrin secretion? | pH drops back down, around 2 |
What causes ulcers? | H. pylori |
What do NSAIDS cause in the stomach? | shut off mucous barrier |
What is the treatment for ulcers? | antibiotic, but it's hard to get it to the right spot |
What is the name of the cell that secretes gastrin? | G cell |
What is the G cell sensitive to? | amino acids in the lumen |
Is gastrin a hormone? | yes |
What does somatostatin do to gastrin? | inhibits - paracrine |
What effect does high H+ cause on somatostatin? | cause secretion of somatostatin |
How does secretin work? | acts as a hormone - inhibits gastrin |
Where is somatostatin secreted? | antrum of the stomach |
Where are the G-cells located? | antrum |
Where does the secretin come from? | duodenum |
What other use does nexium have? | acid reflux |
Why would acid be damaging to the esophagus? | esophagus does not have protective mucus - constant acid wears it down |
Can you have hyperosmotic materials in the stomach? | Yes - stomach wall does not absorb water |
What 2 other things can turn on acid production? | alcohol and caffeine |
Does the chyme enter the small intestine? | NO - small intestine is very sensitive to acid |
What does the duodenum do to neutralize the acidic chyme? | secretes bicarbonate |
Why does the chyme take so long to go from stomach to duodenum | it has to be neutralized - goes slowly |
What role does secretin have in neutralization of acidic chyme in the duodenum? | signals pancreatic ducts to secrete bicarbonate |
Where is bicarb secreted from to the duodenum? | pancreas |
What does CHO trigger in the duodenum? | GLP-1 (glycogen-like peptide 1) |
Where does GLP-1 act? | pancreas -islet |
What does GLP-1 signal to the islet cells produce? | insulin |
What do fats and peptides trigger in duodenum? | CCK -colecystekinin (check spelling) |
What does CCK signal? | secretion of zyomgens (enzymes) from the pancreas |
What do zymogens do? | degrade |
What is the other target site of the CCK besides the pancreas? | gall bladder |
What does the CCK signaling of the gall bladder cause? | secretion of bile |
Where is the acinus located? | pancreas |
What does the acinus hold? | zymogens (inactive until released into duodenum) |
What do duct cells in the pancrease secrete? | HCO3 |
What effect would damage to the pancreas cause? | potential activation of zymogens in wrong place |
What signals duct cells to release HCO3? | secretin |