Question

how is hydrochloric acid made in the stomach?

Answer 1

Hydrochloric acid (HCL), as the name suggests is a compound with highly acidic properties which aids in the digestion of food particles in the stomach. it also kills harmful pathogens present in food and also converts inactive Pepsinogen enzyme into active pepsin.

The HCL is secreted by stomach wall, which consists of two types of cells (Parietal and Chief cells ). the parietal cells contain an important enzyme called Carbonic Anhydrase which runs acid-base reaction and produce bicarbonate and hydrogen ions. the bicarbonate ions move into blood where as hydrogen ions move into stomach via (H⁺- K⁺ ATPase). During this process energy in the form of ATP is utilized to transfer K⁺ ions from stomach to parietal cells and H⁺ ions from parietal cells into stomach.

The chloride ions are transported into stomach lumen through chloride channels. Thus when two oppositively charged ions are present together in the stomach, they combine together and form hydrochloric acid (HCL). The three chemicals (stimuli) which activate Parietal cells to secrete hydrochloric acid are Histamine, Acetylecholine and Gastrin.