ANATOMY

Detailed explanation-1: -Pepsin is a stomach enzyme that serves to digest proteins found in ingested food. Gastric chief cells secrete pepsin as an inactive zymogen called pepsinogen. Parietal cells within the stomach lining secrete hydrochloric acid that lowers the pH of the stomach. A low pH (1.5 to 2) activates pepsin.

Detailed explanation-2: -Of these five components, pepsin is the principal enzyme involved in protein digestion. It breaks down proteins into smaller peptides and amino acids that can be easily absorbed in the small intestine.

Detailed explanation-3: -If we zoom in on a section of the stomach, we can see the epithelial cells which line its inner surface. These epithelial cells secrete mucus which forms a layer that pepsin cannot penetrate. The mucus therefore acts as a barrier to prevent pepsin from coming into contact with the proteins that make up the stomach.

Detailed explanation-4: -The two major pancreatic enzymes that digest proteins in the small intestine are chymotrypsin and trypsin . Trypsin activates other protein-digesting enzymes called proteases, and together, these enzymes break proteins down to tripeptides, dipeptides, and individual amino acids.

Detailed explanation-5: -So, the correct answer is ‘Proteins in stomach’