Describe the process of digestion of proteins in the stomach and small intestine.

Protein digestion begins in the stomach, where the enzyme pepsin breaks proteins into polypeptides in an acidic environment. The partially digested proteins then move to the small intestine, where the enzyme trypsin further breaks them down into amino acids. These amino acids are absorbed by the walls of the small intestine into the bloodstream, where they are used by the body for growth, repair, and energy production.