Digestive System — BIOLOGY STD 9 — Question

There is no digestion of protein in the oral cavity because protein digestive enzymes are absent in the saliva.

1. Digestion of protein in the stomach:

Gastric juice contains HCl and two proenzyme, pepsinogen and prorennin. HCI maintains a pH of 2 - 3.7 and kills bacteria and other pathogens. Gastric juice mixes with food until it becomes semi-solid mass called Chyme. Proenzymes become activated as below:

These enzymes act as follows:

2. Digestion of protein the small intestine

Action of pancreatic juice. It contains proenzymes trypsinogen, chymotry-psinogen and procarboxy peptidase.

Action of intestinal juice. Intestinal juice contains endokinase, aminopeptidase and dipeptidase. Actions of these enzymes are summarized below:

Peptides —Aminopentidase _. cm aller peptides + Amino acid

Peptides —Dipentidase_. amino acid