Question

pharm ch 32

Describe the three of secretory cells in the stomach: cheif, parietal, and mucous cells. Review the role of pepsinogen, hydrochloric acid, intrinsic factor, and prostaglandins and digestion.

Answer 1

Chief cell in the stomach: The gastric chief cell (also known as a zymogenic cell or peptic cell) is a cell in the stomach that releases pepsinogen and chymosin. Pepsinogen is activated into the digestive enzyme pepsin when it comes in contact with acid produced by gastric parietal cells

parietal cell in the stomach: Parietal cells (also known as oxyntic cells) are epithelial cells in the stomach that secrete hydrochloric acid (HCl) and intrinsic factor. They contain an extensive secretory network of canaliculi from which the HCl is secreted by active transport into the stomach.

Mucous cell in the stomach: mucous cells are mucus-producing cells which cover the inside of the stomach, protecting it from the corrosive nature of gastric acid. These cells line the gastric mucosa (mucous neck cells are found in the necks of the gastric pits).

Role of pepsinogen: Pepsinogen is a powerful and abundant protein digestive enzyme secreted by the gastric chief cells as a proenzyme and then converted by gastric acid in the gastric lumen to the active enzyme pepsin.

Role of HCL: The hydrochloric acid in the gastric juice breaks down the food and the digestive enzymes split up the proteins. The acidic gastric juice also kills bacteria. The mucus covers the stomach wall with a protective coating.

Role of intrensic factor: The intrinsic factor (IF) is a glycoprotein produced by the parietal cells (oxyntic cells) located at the gastric body and fundus. Intrinsic factor plays a crucial role in the transportation and absorption of the vital micronutrient vitamin B12 (cobalamin, Cbl) by the terminal ileum.

Role of prostaglandins: Prostaglandins are found in high concentration in the gastric mucosa and gastricjuice. Exogenous prostaglandins inhibit acid secretion, stimulate mucus and bicarbonate secretion, alter mucosal blood flow, and provide dramatic protection against a wide variety of agents which cause acute mucosal damage.