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13 Cards in this Set

  • Front
  • Back
How is Cl- extruded down its electrochemical gradient?
Through channels that are activated by cAMP.
The H+ that is extruded, where does it come from?
It comes from H2CO3, and H2CO3 in turn is formed by the hydration of CO2.
What initiates the formation of H2CO3 via CO2 hydration?
Carbonic anhydrase. The parietal cells are rich in this enzyme.
The HCO3 formed by dissociation of H2CO3 is extruded how?
by an antiport in the basolateral membrane of the parietal cells that exchanges HCO3 for another anion, and since Cl- is the most abundant anion in interstitial fluid, the exchange is mainly for Cl-.
because of the efflux of HCO3, into the blood, the stomach has a negative respiratory quotient(RQ-). TRUE/FALSE
TRUE.The amount of CO2 in areterial blood is greater than the amount in gastric venous blood.
What is the postprandial alkaline tide?
When gastric acid secretion is elevated after a meal, sufficient H+ may be secreted to raise the pH of systemic blood, and make the urine alkaline(postprandial alkaline tide).
How is acid secretion stimulated?
It is stimulated by histamine via H2 receptors and by acetylcholine via M3 muscarinic receptors.
Does Gastrin act directly as well?
It probably acts directly as well, although the main stimulation by gastrin is via enterochromaffin like cells.
What is the difference between the H2 receptors and muscarinic receptors?
The H2 receptors increase intracellular cAMP via G, whereas the muscarinic receptors and gastrin receptors exert their effects by increasing intracellular free Ca2+.
Prostaglandins, particularly those of the E series, inhibit acid secretion by activating G1. TRUE/FALSE
Gastrin also acts by stimulating the secretion of histamine from enterochromaffin like cells. TRUE/FALSE
TRUE. these are vesicle and granule containing cells that are the predominant endocrine cell type in the acid secreting portion of the stomach.
Are ECL cells inhibited by somatostatin?
Yes. They undergo hypertrophy when gastric acid secretion is suppressed for prolonged periods.
Does hypoglycemia have an effect on acid secretion?
It acts via the brain and vagal efferents to stimulate acid and pepsin secretion.
Other stimulants include alcohol and caffeine, both of which act directly on the mucosa.