Which cells of the stomach secrete hydrochloric acid?

• A. Parietal cells
• B. Chief cells
• C. G cells
• D. Mucous neck cells

Answer: (A)

The main idea tested is which stomach cells produce hydrochloric acid. Parietal cells in the gastric glands secrete HCl into the stomach lumen. They use a proton pump (H+/K+-ATPase) to move hydrogen ions into the lumen, with chloride ions accompanying to form hydrochloric acid. This acidic environment is crucial for denaturing proteins and activating pepsinogen to pepsin, kicking off protein digestion. Parietal cells also secrete intrinsic factor, important for vitamin B12 absorption. The other cells have different roles: chief cells secrete pepsinogen, G cells release gastrin to stimulate acid secretion, and mucous neck cells produce mucus and bicarbonate to protect the lining. So, hydrochloric acid is produced by parietal cells.