Factors controlling secretion of the stomach?

Secretion of the stomach is controlled by a variety of factors, including:

1. Nervous control:

- Cephalic phase: The sight, smell, or thought of food stimulates the secretion of gastric juices. This is mediated by the vagus nerve.

- Gastric phase: Distension of the stomach and the presence of food in the stomach stimulate the secretion of gastric juices. This is also mediated by the vagus nerve.

- Intestinal phase: The presence of food in the intestine inhibits the secretion of gastric juices. This is mediated by hormones such as cholecystokinin (CCK) and gastric inhibitory peptide (GIP).

2. Hormonal control:

- Gastrin: Gastrin is a hormone produced by the G cells of the stomach. It stimulates the secretion of gastric juices, including hydrochloric acid and pepsin.

- Secretin: Secretin is a hormone produced by the S cells of the duodenum. It stimulates the secretion of bicarbonate-rich fluid from the pancreas and the liver.

- Somatostatin: Somatostatin is a hormone produced by the D cells of the stomach and the pancreas. It inhibits the secretion of gastric juices and hormones such as gastrin and secretin.

3. Local factors:

- pH of the stomach: The pH of the stomach plays a role in the secretion of gastric juices. Acidic pH stimulates the secretion of gastrin and inhibits the secretion of somatostatin.

- Presence of food: The presence of food in the stomach stimulates the secretion of gastric juices. This is mediated by both mechanical and chemical factors.

4. Drugs and other substances:

- Alcohol: Alcohol stimulates the secretion of gastric juices.

- Caffeine: Caffeine stimulates the secretion of gastric juices.

- Nicotine: Nicotine inhibits the secretion of gastric juices.

- Non-steroidal anti-inflammatory drugs (NSAIDs): NSAIDs inhibit the production of prostaglandins, which play a role in protecting the stomach lining. This can lead to increased secretion of gastric juices and damage to the stomach lining.