What is the primary secretion of chief cells in the stomach?

Chief cells are specialized cells located in the gastric glands of the stomach lining, and their primary function is to secrete digestive enzymes. The main secretion produced by chief cells is pepsinogen. Pepsinogen is an inactive precursor (zymogen) of the enzyme pepsin, which plays a crucial role in protein digestion. Once pepsinogen is secreted into the stomach and encounters the acidic environment (due to hydrochloric acid secreted by parietal cells), it is converted into its active form, pepsin. This activation process is essential for initiating the breakdown of proteins into smaller peptides.

Pepsin's activity is crucial for the digestive process, making the secretion by chief cells vital for effective protein digestion in the gastric phase of digestion. Understanding this function helps elucidate the complex interactions that occur within the stomach during the digestive process.