Final answer:
The protection of gastric epithelial cells from corrosion by acid and digestion by pepsin is afforded by the mucosal barrier of the stomach, which includes a thick coating of bicarbonate-rich mucus, tight junctions between epithelial cells, and rapid cell replacement.
Step-by-step explanation:
The protection of gastric epithelial cells from corrosion by acid and digestion by pepsin is afforded by the mucosal barrier of the stomach. This barrier consists of several components, including a thick coating of bicarbonate-rich mucus that forms a physical barrier and neutralizes acid, tight junctions between epithelial cells that block gastric juice penetration, and the rapid replacement of damaged cells by stem cells. Additionally, the stomach has a thick mucus lining that protects the underlying tissue from digestive juices like pepsin.