DIGESTION AND ABSORPTION
The mechanical digestion of protein begins in the mouth, where the teeth grind the food into small pieces. Chemical digestion begins in the stomach. Hydrochloric acid prepares the stomach so that the enzyme pepsin can begin its task of reducing proteins to polypeptides.
After the polypeptides reach the small intestine, three pancreatic en-zymes (trypsin, chymotrypsin, and carboxypeptidase) continue chemical digestion. Intestinal peptidases finally reduce the proteins to amino acids.
After digestion, the amino acids in the small intestine are absorbed by the villi and are carried by the blood to all body tissues. There, they are used to form needed proteins.