How does stomach acid break down food?

How does stomach acid break down food?

Stomach acid, also known as gastric acid, is a secretion of the stomach used to break down food. It consists primarily of hydrochloric acid, with significant amounts of sodium chloride and potassium chloride. The acid has a pH of between 1 and 2, although at times in the process it is a bit higher. Stomach acid works in tandem with enzymes to break food down so that nourishment can be derived from it to help the body function, and so that the waste can be discarded. The acid made by the stomach is incredibly strong, so potent that undiluted it would burn through wood, and so the lining of the stomach itself has to be very tough to protect from being burned through.

The stomach contains cells called parietal cells, which excrete stomach acid. This raises the acidity of the stomach drastically, which in turn interacts with food in the stomach. The stomach acid denatures the proteins present within food, exposing their peptide bonds. At the same time, stomach acid activates an important enzyme, pepsinogen, which is also secreted by the stomach. When it activates this enzyme it turns it into pepsin, which then breaks the bonds in proteins that link together the various amino acids, allowing these amino acids to be utilized.