What do chief cells secrete in the stomach?

Chief cells in the stomach are specialized epithelial cells primarily responsible for the secretion of pepsinogen, which is an inactive precursor of the digestive enzyme pepsin. When pepsinogen enters the acidic environment of the stomach, it is activated to its active form, pepsin, which plays a crucial role in the digestion of proteins. This process is essential for breaking down dietary proteins into smaller peptides that can be further digested and absorbed in the intestine.

In contrast, other cells in the gastric gland have different secretions. For instance, parietal cells secrete hydrochloric acid, which creates the highly acidic environment necessary for pepsin activation and also aids in the digestion of food. Additionally, parietal cells produce intrinsic factor, a protein critical for the absorption of vitamin B12 in the intestines. Gastrin, on the other hand, is a hormone produced by G cells in the gastric mucosa that stimulates the secretion of gastric acid and aids in gastric motility.

Thus, the primary function of chief cells centers around the production of pepsinogen, making pepsinogen the correct answer regarding what chief cells secrete in the stomach.