What is the gastric mucosa?
The stomach mucosa is a layer of stomach composed of epithelium, propria and mucosae muscularis. The epithelium covers the surface of the gastric mucosa and consists of one layer of column cells that secrete a strong, slippery, pure liquid called mucus and also alkaline fluid. Mucus and alkaline fluid provide the protection of the epithelium against mechanical damage and stomach acid. The surface of the gastric mucosa also contains numerous holes from the pipes called stomach points in which one or more stomach glands empty. Both cardiac and pyloric gland areas contain primarily gland cells secreting mucus, but they also contain gastrin cells (G cells) that eliminate hormonal gastrin. Oxyntic (acid-forming) glandular area contains three types of cells, including secretory mucosal cells, parietal or oxyntic cells that eliminate hydrochloric and internal factor and pepsinogen secreting peptic or main cells.
Gastrin promotes secretion of hydrochloric acid and pepsinogens by stimulating parietal cells and peptic cells. The hydrochloric acid decomposes food material, kills the most used microorganisms and catalyzes the conversion of inactive pepsinogen into active pepsin, which is responsible for digestion of proteins. Pepsinogens are contained in the gagules in peptic or main cells and are released by exocytosis. The presence of hydrochloric acid provides the necessary acid conditions for converting pepsinogen into pepsin. The internal factor binds vitamin B 12 and allows its absorption in the ileum.
The basic factors that stimulate stomach are acetylcholine, gastrin and histamine. Acetylcholine stimulates mucus secretion with mucus cells, hydrochloric acid by parietal or oxyntic cells and pepsinogen with peptic or main cells. Gastrin and histamine only apply their effects on parietal or oxyntic cells.
runHEM Normal stomach function is usually exfolized into lumens. These cells are replaced by regenerative cells that have the ability to differentiate to columnar epithelial cells and migrate to their new location. In addition, these cells of the column stem cells are dispersed between the mucosal cells. The stomach uses these cells to repair the epithelium damage on the surface.
There are also diffuse cells of the neuroendocrine system (today) dispersed, among other epithelial cells of the gastric mucosa. The cells of the day are types of endocrine cells in various places throughout the body. These cells secrete hormonal substances.