Upon activation by stomach acidity, the secretions of the parietal cells ________.

Question

Quizplus · Accepted Answer

The parietal cells secrete hydrochloric acid, which lowers the pH of the stomach and activates pepsinogen, an enzyme produced by chief cells. Pepsinogen is converted to pepsin, which begins the chemical digestion of protein in the stomach.

Option B is incorrect because mechanical digestion of lipids occurs mainly in the mouth and small intestine, and not in the stomach.

Option C is incorrect because the chemical digestion of lipids mainly occurs in the small intestine, not in the stomach.

Option D is incorrect because delaying digestion until the food arrives in the small intestine would not be beneficial as gastric emptying occurs continuously and not all at once.

Upon Activation by Stomach Acidity, the Secretions of the Parietal