| Part type : | part |
| On both sides : | ??? |
| Digitisation completed : | false |
Structure
The otherwise smooth lining of the stomach mucosa is dotted with millions of deep gastric pits, which lead to the gastric glands. Gastric glands are simple branched tubular glands located in the lamina propia of the cardia, fundus and pylorus. Parietal (oxyntic) cells are concentrated in the upper half of the gastric glands. Parietal cells possess a unique intracellular tubulovesicular system, many mitochondria and secretory intracellular canaliculi (deep invaginations of the apical plasma membrane) lined by microvilli. When stimulated to secrete HCl, the number and length of the microvilli increase and the complexity of the tubulovesicular system decreases. This suggests that the tubulovesicles are storage forms of microvilli, thus contributing to the increase in surface areas of the intracellular canaliculi.
Function
The otherwise smooth lining of the stomach mucosa is dotted with millions of deep gastric pits, which lead to the gastric glands. Gastric glands are simple branched tubular glands located in the lamina propia of the cardia, fundus and pylorus. Parietal (oxyntic) cells are concentrated in the upper half of the gastric glands. They secrete hydrochloric acid (HCl) and gastric intrinsic factor. The latter is necessary for the absorption of vitamin B12 in the ileum. HCl makes the stomach contents extremely acidic (pH 1.5-3.5), a condition necessary for the activation and optimal activity of the digestive enzyme pepsin. In addition, the acidic environment is harsh enough to kill many of the bacteria ingested with food.
