How is gastric juice formed?

Gastric juice is a digestive fluid produced by the stomach. It is composed of hydrochloric acid, pepsin, and mucus. The production of gastric juice is regulated by a variety of factors, including the presence of food in the stomach, the pH of the stomach contents, and the activity of the nervous system.

The first step in the formation of gastric juice is the release of gastrin, a hormone produced by the G cells of the stomach. Gastrin stimulates the parietal cells of the stomach to secrete hydrochloric acid. Hydrochloric acid creates an acidic environment in the stomach, which is necessary for the activation of pepsin.

Pepsin is a protease that breaks down proteins into smaller peptides. It is produced by the chief cells of the stomach in an inactive form called pepsinogen. Pepsinogen is activated by the acidic environment of the stomach.

Mucus is produced by the mucous cells of the stomach. It protects the stomach lining from the acidic environment of the stomach and provides lubrication for food as it moves through the stomach.

The production of gastric juice is also regulated by the nervous system. The vagus nerve stimulates the release of gastrin and hydrochloric acid. The sympathetic nervous system inhibits the release of gastric juice.

The production of gastric juice is essential for the digestion of food. Hydrochloric acid kills bacteria and denatures proteins, making them more susceptible to digestion by pepsin. Mucus protects the stomach lining from the acidic environment of the stomach and provides lubrication for food as it moves through the stomach.