Hydrochloric acid contributes to protein digestion by supplying H+ which activates pepsinogen, the precursor to pepsin. Pepsinogen is secreted by chief cells in the gastric glands of the body and antrum of the stomach.
Carbohydrates are digested into maltose in the mouth and protein digestion begins in the stomach.
In the stomach, food undergoes chemical as well as physical digestion.
Due to the peristaltic action of the muscles the bolus breaks up in the stomach wall and mixes well into a chyme. ( <em>Physical digestion</em> )
Several secretions flow into the stomach.
It is collectively known as gastric juice.
Also the juice contains pepsin and HCL acid.
Here, the enzyme pepsin acts on the proteins in the food and forms polypeptides, which are intermediate products of life. ( <em>Chemical digestion</em> )
And the function of the HCL acid is to stimulate pepsin enzyme and make it active
