The gastric gland is the primary secretory unit of the stomach. The gastric gland is an essential body component because it secretes gastric juice and protective mucus. Mucus coats the stomach and helps it dilute enzymes and acids during the digestive process.
The gastric gland system contains a variety of component cells and starts at the gastric pit or the opening to the lumen of the stomach. There are three types of gastric glands. Each is distinguishable by location and type of secretion. The cardiac gastric glands are positioned in the beginning of the stomach. The true or intermediate gastric glands are located in the central stomach regions. The pyloric glands are found in the terminal stomach region. Both the pyloric and cardiac glands secrete mucus that protects the stomach from self-digestion.
The intermediate gastric glands produce the bulk of the digestive substances secreted by the stomach. These glands contain three primary cell types: parietal, zymogenic and mucous neck cells. The zymogenic or chief cells produce the enzymes pepsin and rennin. Pepsin digests proteins and rennin curdles milk.
The parietal cells located throughout the gland are responsible for the production of hydrochloric acid. Hydrochloric acid is essential to activation of other enzymes in the body. Mucous neck sells are vital to mucus secretion.