22. ***Gastric parietal cell Flashcards Preview

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Flashcards in 22. ***Gastric parietal cell Deck (11)
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• The proton pump of parietal cells can be found on which side of the cell?

The luminal side


• The proton pump of the parietal cells pumps ____ into the cell and sends ____ out of the cell and into the lumen.

Potassium ions; protons


• A patient in the United States with raw epigastric pain after eating might get relief with which class of medication?

Proton pump inhibitors (H2 receptor blockers are also useful, but most guidelines recommend starting with a PPI first)


• How does acetylcholine stimulate acid production by parietal cells?

It activates an M3 receptor on the cells that directly stimulates acid secretion through the proton pump via a G-protein cascade


• In what two ways does gastrin stimulate acid production by parietal cells?

Gastrin primarily stimulates histamine production by ECL cells, and binds directly to parietal cell cholecystokinin (CCKB) receptors


• Carbonic anhydrase is an enzyme that converts carbonic acid to what two molecules in the parietal cell?

Carbon dioxide and water


• As a proton leaves the parietal cell on the luminal side, bicarbonate leaves the cell via the basolateral side and causes what effect?

The alkaline tide, a transient increase in interstitial pH secondary to gastric acid production/bicarbonate secretion from the parietal cell


• What is the second messenger that is used in histamine-induced acid secretion?

cAMP, stimulated by the H2 receptor


• What substances inhibit acid secretion by the parietal cells?

Prostaglandins, somatostatin


• Each of these pathways has an inhibitory drug to decrease acid release, except for which one?

(ACh to M3, gastrin to CCKB, histamine to H2)
Gastrin to CCKB receptor, as gastrin has no clinically useful pharmacologic inhibitor


• A woman with too much gastric acid takes a drug that decreases parietal cell cAMP levels. By what pathway does this drug act?

Acts via the Gi pathway to decrease parietal cell cAMP levels and lower acid secretion (the drug is misoprostol, a prostaglandin analog)

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