Question

In your own words, describe the physiologic functions of the following gastric secretions: hydrochloric acid, pepsin, gastric lipase, intrinsic factor. In your own words, describe the stages of gastric activity: cephalic, gastric, and intestinal.

Answer 1

Hydrochloric acid (HCl) is a component of gastric juice plays an important role in creating pH required for pepsin activity.

Pepsin is a protein digesting enzyme secreated by gastric chief cell, it covert protein into smaller smaller peptides, proteoses and peptons.

Gastric lipase is responsible for digestion of dietary fats in stomach. It is secreated by chief cells in stomach. Catalyse lipolytic process. Gastric lipase is important in newborn as they help to efficiently digest milk.

Intrinsic factor is secreated by parietal cells. They play an important role in the absorption and transportation of vitamin b12.

Stages of gastric activity

Cephalic phase :-

This occurs before the entry of the food into the stomach. This secretion is initiated by sight, smell, thought or taste of food. This phase is under neural control via vagus.

Gastric phase :-

This phase is initiated by the entry into the stomach. This is controlled by neural and hormonal mechanism. This lead to gastic juice secretion. Majority of gastric secretion occur in this phase

Intestinal phase :-

This focus when the chyme begins to empty into duodenum. Initially the secretion is increased and later it is inhibited.

When partially digested food begins to fill duodenum intestinal mucosa secrete intestinal gastrin which stimulate gastric juice secretion.

when the intestine distend with chyme the enterogastric reflex inhibit the gastric juice secretion.