Gastric JuicesIn addition to the mechanical digestion caused by churning, there is also chemical digestion happening within the stomach. Specifically, we see the chemical digestion of proteins by digestive fluids. These acidic digestive fluids that are secreted by the gastric glands in the mucous membrane of the stomach are collectively referred to as gastric juices. We previously learned that secretions of gastric juices from the gastric glands are regulated by the parasympathetic nervous system. This involuntary nervous system increases secretions when activated by the sight, smell or physical presence of food in the digestive tract. In addition, the presence of food and the change in the pH of the stomach stimulate the release of a hormone called gastrin. This is a hormone secreted by glands in the mucous membrane of the stomach that stimulates the production of gastric juices.

Epithelial cells secrete enzymes in the gastric glandsGastric Epithelial CellsSo, you can see that there are a couple of triggers for the production of gastric juices, and this leads to a surprisingly large volume of gastric juice produced during the day. Under normal circumstances, approximately two or three liters of gastric juices are produced in your stomach in a 24-hour period. That is enough to fill at least one 2-liter bottle of soda, and this is all happening inside of you without your conscious awareness.