What is the main enzyme found in the stomach involved in digestion?

Pepsin is the main enzyme found in the stomach that is crucial for the process of digestion, particularly for breaking down proteins into smaller peptides. It is secreted by the stomach lining in an inactive form known as pepsinogen, which is then activated by the acidic environment of the stomach, created by gastric acid (hydrochloric acid). This activation is vital, as pepsin can only function effectively in the low pH of the stomach.

Proteins are large macromolecules, and pepsin specifically targets peptide bonds within these molecules, leading to their digestion into smaller fragments that can be further processed by other enzymes in the small intestine. This enzymatic action initiates the complex process of protein digestion, which is essential for the absorption of amino acids and the overall metabolism of nutrients necessary for the body's functions.

In contrast, amylase is primarily involved in carbohydrate digestion and is found in saliva and pancreatic fluid. Lipase is associated with the digestion of fats and is produced mainly by the pancreas. Bile, produced in the liver and stored in the gallbladder, aids in the emulsification of fats but is not an enzyme; rather, it is a digestive fluid.