What is the function of the chief cell?
Chief cells (B or arrow) are located, in cluster, at the base of the glands. They synthesize and secret hydrolytic enzymes, which are activated at acid pH. These enzymes include gastric lipase, rennin and pepsin, which is secreted as pepsinogen and activated in the lumen. Pepsin hydrolyzes proteins.
Parietal cells (also known as oxyntic or delomorphous cells), are the epithelial cells that secrete hydrochloric acid (HCl) and intrinsic factor. These cells are located in the gastric glands found in the lining of the fundus and in the cardia of the stomach.
- Small pores called gastric pits contain many exocrine cells that secrete digestive enzymes and hydrochloric acid into the lumen, or hollow region, of the stomach. Mucous cells found throughout the stomach lining and gastric pits secrete mucus to protect the stomach from its own digestive secretions.
- Pepsin is an endopeptidase that breaks down proteins into smaller peptides (that is, a protease). It is produced in the stomach and is one of the main digestive enzymes in the digestive systems of humans and many other animals, where it helps digest the proteins in food.
- Mucus is composed of water, epithelial (surface) cells, dead leukocytes, mucin, and inorganic salts. Mucus is produced by mucous cells, which are frequently clustered into small glands located on the mucous membrane that lines virtually the entire digestive tract.
The two main types of exocrine secretory cells of the stomach are parietal cells and chief cells. Parietal cells secrete hydrochloric acid and chief cells secrete digestive enzymes such as pepsin.
- Goblet cells reside throughout the length of the small and large intestine and are responsible for the production and maintenance of the protective mucus blanket by synthesizing and secreting high-molecular-weight glycoproteins known as mucins.
- Hydrochloric acid is a fluid secreted by the parietal cells of the stomach. It kills bacteria, activates pepsinogen -> pepsin, and lowers the pH of the stomach. Its acidity denatures proteins, aiding in protein digestion. It has a pH of 1.
- Parietal cells (also known as oxyntic or delomorphous cells), are the epithelial cells that secrete hydrochloric acid (HCl) and intrinsic factor. These cells are located in the gastric glands found in the lining of the fundus and in the cardia of the stomach.
In anatomy, the G cell (or γ-cell) is a type of cell in the stomach and duodenum that secretes gastrin. It works in conjunction with gastric chief cells and parietal cells. G cells are found deep within the pyloric glands of the stomach antrum, and occasionally in the pancreas and duodenum.
- Delta cells (δ-cells or D cells) are somatostatin-producing cells. They can be found in the stomach, intestine and the pancreatic islets. Ghrelin can also strongly stimulate somatostatin secretion, thus indirectly inhibiting insulin release.
- Cholecystokinin, previously called pancreozymin, is synthesized and secreted by enteroendocrine cells in the duodenum, the first segment of the small intestine. Its presence causes the release of digestive enzymes and bile from the pancreas and gallbladder, respectively, and also acts as a hunger suppressant.
- In the digestive tract pepsin effects only partial degradation of proteins into smaller units called peptides, which then either are absorbed from the intestine into the bloodstream or are broken down further by pancreatic enzymes.
Updated: 3rd October 2019