How does hydrochloric acid help in facilitating the action of pepsin?
Show answer & explanation
Correct answer: A
Explanation
The correct answer is Option 1. i.e. Hydrochloric acid creates an acidic medium which facilitates the action of the enzyme pepsin..
Hydrochloric acid (HCl), another component of the gastric juice, plays a crucial role in creating the pH required for pepsin activity. Parietal cells produce HCl by secreting hydrogen and chloride ions. When pepsinogen and hydrochloric acid exist together in the gastric juice, pepsin takes its active form.
An increase in HCl and decreasing pH level also signal gastric motility to turn on to move the partially digested bolus of food along and help kill bacteria normally ingested with food. The pH of the stomach is regulated by a negative feedback loop by antral D cells that release somatostatin which inhibits the release of gastrin. As food moves out of the stomach, the H+ concentration increases which also serves to inhibit HCl secretion.
Hydrochloric acid contributes to protein digestion by supplying H+ which activates pepsinogen, the precursor to pepsin. Pepsinogen is secreted by chief cells in the gastric glands of the body and antrum of the stomach.