Gut reaction

[Allan]

What stops your stomach from digesting itself?

[Ginbottle]

When the stomach is empty, bile is produced from the gall bladder to stop the stomach becoming too acid.

[incitatus]

The bile duct leads to the gut, not the stomach. The answer is snot. The stomach wall is protected by a constantly released layer of mucus. This acts rather like a barrier cream. When the stomach becomes too acidic, due to anxiety, or H. pylori or whatever, even the snot wont save you. Bile does regulate acidity further down the line, aand contains digestive enzymes to help osmosis.

[dogbreath]

Your stomach is made up of several layers: The serosa - the outer layer that acts as a covering for the other layers. Two muscle layers - the middle layers that propel food from the stomach into the small intestine. The mucosa - the inner layer made up of specialised cells, including parietal cells, g-cells and epithelial cells. Parietal cells produce hydrochloric acid, a strong acid that helps to break down food. The g-cells produce gastrin, a hormone that helps the parietal cells make hydrochloric acid. The stomach is protected by the epithelial cells, which produce and secrete a bicarbonate-rich solution that coats the mucosa. Bicarbonate is alkaline and neutralises the acid secreted by the parietal cells. This continuous supply of bicarbonate is the main way that your stomach protects itself from digesting itself.

[Ginbottle]

The hormones that control digestion are gastrin, secretin, and cholecystokinin (CCK):  Gastrin causes the stomach to produce an acid for dissolving and digesting some foods. It is also necessary for the normal growth of the lining of the stomach, small intestine, and colon.  Secretin causes the pancreas to send out a digestive juice that is rich in bicarbon-ate. It stimulates the stomach to produce pepsin, an enzyme that digests protein, and it also stimulates the liver to produce bile.  CCK causes the pancreas to grow and to produce the enzymes of pancreatic juice, and it causes the gallbladder to empty.