Digestive System Overview · Physiology

What is the physiological significance of the 'alkaline tide' observed after a large meal?

  1. An increased secretion of bicarbonate directly into the duodenal lumen after eating
  2. Release of bicarbonate into the blood in exchange for chloride during HCl production
  3. The breakdown of dietary proteins into basic amino acids within the acidic stomach lumen
  4. A systemic decrease in blood pH resulting from heightened gastric secretory activity
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Correct answer: Release of bicarbonate into the blood in exchange for chloride during HCl production

When parietal cells secrete $H^+$ into the stomach lumen, they transport $HCO_{3}^{-}$ across the basolateral membrane into the bloodstream. This efflux of bicarbonate causes a transient increase in the pH of the venous blood leaving the stomach.

Difficulty: Medium Question 26 of 39

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