The gastric glands are located in different regions of the stomach. These are the fundic glands, the cardiac glands, and the pyloric glands. The glands and gastric pits are located in the stomach lining. The glands themselves are in the lamina propria of the mucous membrane and they open into the bases of the gastric pits formed by the epithelium. The various cells of the glands secrete mucus, pepsinogen, hydrochloric acid, intrinsic factor, gastrin, histamine and bicarbonate.
The cardiac glands are found in the cardia of the stomach which is the part nearest to the heart, enclosing the opening where the esophagus joins to the stomach. Only cardiac glands are found here and they primarily secrete mucus. They are fewer in number than the other gastric glands and are more shallowly positioned in the mucosa. There are two kinds - either simple tubular with short ducts or compound racemose resembling the duodenal Brunner's glands
The fundic glands (or oxyntic glands), are found in the fundus and body of the stomach. They are simple almost straight tubes, two or more of which open into a single duct. Oxyntic means acid-secreting and they secrete hydrochloric acid (HCl) and intrinsic factor.
The pyloric glands are located in the antrum of the pylorus. They secrete gastrin produced by their G cells.
Gastric gland, any of the branched tubules in the inner lining of the stomach that secrete gastric juice and protective mucus.
There are three types of gastric glands, distinguished from one another by location and type of secretion. The cardiac gastric glands are located at the very beginning of the stomach; the intermediate, or true, gastric glands in the central stomach areas; and the pyloric glands in the terminal stomach portion. Both the cardiac and pyloric glands secrete mucus, which coats the stomach and protects it from self-digestion by helping to dilute acids and enzymes.
The intermediate gastric glands produce most of the digestive substances secreted by the stomach. These glands are narrow tubules composed of three major cell types: zymogenic, parietal, and mucous neck cells. At the base of the gland are the zymogenic (chief) cells, which are thought to produce the enzymes pepsin and rennin. (Pepsin digests proteins, and rennin curdles milk.) Parietal, or oxyntic, cells occur throughout the length of the gland and are responsible for the production of hydrochloric acid, which is necessary to activate the other enzymes. The purpose of mucous neck cells is to secrete mucus.
There is usually a small, constant production of gastric juices, but their secretion can be stimulated by numerous means. Tasting, smelling, or thinking of food tends to increase enzyme secretions. The production of gastric juices is limited while a person is asleep, but production resumes upon awakening. Consumed food provides additional stimulation necessary for mucus secretion. Some foods also contain chemicals that activate enzyme production. Psychological states of fear, sadness, or withdrawal may reduce gastric secretion.