GENERAL HISTOLOGY

Detailed explanation-1: -Gastric chief cells secrete pepsin as an inactive zymogen called pepsinogen. Parietal cells within the stomach lining secrete hydrochloric acid that lowers the pH of the stomach. A low pH (1.5 to 2) activates pepsin.

Detailed explanation-2: -The parietal cells secrete hydrochloric acid (HCl), which lowers the pH of the gastric juice (water + enzymes + acid). Hydrochloric acid inactivates salivary amylase and catalyzes the conversion of pepsinogen to pepsin.

Detailed explanation-3: -Hydrochloric acid secretion by the gastric parietal cell is necessary for pepsinogen activation (pH<5) and for the reduction of bacterial colonization. The main stimulants of gastric acid secretion are histamine, gastrin, and acetylcholine.

Detailed explanation-4: -Gastrin is a hormone that is produced by ‘G’ cells in the lining of the stomach and upper small intestine, and released into the blood circulation. During a meal, gastrin stimulates the stomach to release gastric acid (hydrochloric acid).

Detailed explanation-5: -A substance made by cells in the stomach. Acid in the stomach changes pepsinogen to pepsin, which breaks down proteins in food during digestion.