Pepsin is a powerful protein-digesting enzyme. Why does not it digest the stomach walls, which are mostly proteins?

Question

Pepsin is a powerful protein-digesting enzyme. Why does not it digest the stomach walls, which are mostly proteins?

Accepted Answer

We saw that pepsin is not released in its active form. Rather it is secreted as inactive pepsinogen, which requires HCI for activation. The mucous of gastric juice form a thick coating over the inner walls of the stomach and neutralizes the HCI there. It makes pepsinogen difficult to be activated and to attack stomach walls.