Chemical digestion of protein

Chemical digestion of proteins begins in the stomach and ends in the small intestine. Here are the steps:

1. Ingestion: The process begins when you consume a protein source such as meat or beans.

2. Stomach: Once the protein reaches the stomach, the gastric glands secrete gastric juice which contains hydrochloric acid and the enzyme pepsin. The hydrochloric acid denatures the protein, unravelling the protein strands and exposing the peptide bonds. Pepsin, which works best in the acidic environment of the stomach, then begins to break down the protein into smaller units called peptides or polypeptides.

3. Small Intestine: The partially digested protein then moves into the small intestine. Here, it is acted upon by the enzymes trypsin, chymotrypsin, and carboxypeptidase that are produced by the pancreas and secreted into the small intestine. These enzymes break down the peptides into even smaller units - amino acids.

4. Absorption: The amino acids are then absorbed by the villi in the small intestine and enter the bloodstream. From here, they can be transported to cells throughout the body where they are used to build new proteins and repair tissues.

5. Excretion: Any undigested protein is passed into the large intestine for excretion.

This is the process of chemical digestion of proteins in the human body.