Send to

Choose Destination

Physiology, Pepsin.


Heda R1, Tombazzi CR2.


StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2019-.
2018 Dec 19.

Author information

University of Tennessee HSC
University of Tennessee, Memphis


The stomach plays a critical role in the early stages of food digestion. Specifically, the stomach lining secretes a mixture of compounds, collectively known as "gastric juice." Gastric juice comprises water, mucus, hydrochloric acid, pepsin, and intrinsic factor. Of these 5 components, pepsin is the principal enzyme involved in digestion of protein. However, pepsin is released in its inactive form, or zymogen form, known as pepsinogen. By secreting pepsin in its inactive form, the stomach prevents digestion of protective proteins in the lining of the digestive tract. Specific cells within the gastric lining, known as the chief cells, release pepsin when stimulated by gastrin, another gastrointestinal hormone, and acetylcholine, a neurotransmitter. As chief cells release pepsinogen, activation by an acidic environment is necessary. Hydrochloric acid, another component of the gastric juice, plays a crucial role in creating the acidic environment required for pepsin activity. Cells that are known as parietal cells release hydrogen ions through a proton pump. Parietal cells also release chloride ions to form hydrochloric acid. Similar to chief cells, gastrin and acetylcholine also stimulate parietal cells to release hydrochloric acid. The most potent activator of the parietal cells, however, is histamine. When both pepsinogen and hydrochloric acid are present in the gastric juice, pepsin takes its active form.

Copyright © 2019, StatPearls Publishing LLC.

Supplemental Content

Loading ...
Support Center