Question

why does stomach secrete pepsin in ian inactive form?​

Answer 1

Pepsinogen is secreted by the Chief cells present in the stomach wall in response to lower pH, which results from the enhanced secretion of HCl, in response to specific stimuli, such as the parasympathetic response to taste, smell and sight in the cephalic phase, distention in the gastric phase etc.

Exposure to low pH in the stomach lumen activates an auto-catalytic process by which Pepsinogen, a zymogen (inactive enzyme precursor), gets activated to Pepsin. However, pepsin cannot be secreted in the active form.

Secretion of zymogens protects the stomach wall, primarily the chief cells that secrete it, from auto-digestion.

If pepsin was secreted in the active form, it would break down the mucosal barrier and expose the underlying tissue to corrosion by HCl and the proteolytic enzymes, leading to ulcer formation.

Hope this helps! :)

Answer 2

Pepsinogen, inactive precursor formof pepsin, is secreted by Chief cells in the stomach. Pepsinogen is activated by Hydrochloric acid (secretion from Parietal cells) because Hydrochloric acid provides the necessary acidic environment for which pepsin works best.