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Mucous cells of the stomach lining secrete mucus (pink) into the lumen. Mucus (/ ˈ m j uː k ə s /, MEW-kəs) is a slippery aqueous secretion produced by, and covering, mucous membranes. It is typically produced from cells found in mucous glands, although it may also originate from mixed glands, which contain both serous and mucous cells.
Mucins (/ ˈ m juː s ɪ n /) are a family of high molecular weight, heavily glycosylated proteins (glycoconjugates) produced by epithelial tissues in most animals. [1] Mucins' key characteristic is their ability to form gels; therefore they are a key component in most gel-like secretions, serving functions from lubrication to cell signalling to forming chemical barriers. [1]
The mucus produced by these cells is extremely important, as it prevents the stomach from digesting itself. [5] Parietal cells produce potent hydrochloric acid, which damages cells. Gastric chief cells produce pepsinogen, which is activated by the acid to form pepsin. Pepsin is a protease that can digest and damage stomach cells.
A variety of maize grows aerial roots that produce a sweet mucus. The Sierra Mixe is a tall variety that survives in poor soils without fertilizer in Oaxaca, Mexico, and the mucilage has been shown to support nitrogen fixation through bacteria that thrive in its high-sugar, low-oxygen environment. [18]
A peptide hormone, gastrin, produced by G cells in the gastric glands, stimulates the production of gastric juice which activates the digestive enzymes. Pepsinogen is a precursor enzyme ( zymogen ) produced by the gastric chief cells , and gastric acid activates this to the enzyme pepsin which begins the digestion of proteins .
Gastrin is a hormone produced by enteroendocrine G cells in the pyloric glands. [1] All three of these stimulate parietal cells to secrete hydrochloric acid and intrinsic factor. The chief cells secrete pepsinogen in response to gastrin and especially Ach, and ACh also stimulates mucus secretion. [1]
In most vertebrates, digestion is a multistage process in the digestive system, starting from ingestion of raw materials, most often other organisms. Ingestion usually involves some type of mechanical and chemical processing. Digestion is separated into four steps: Ingestion: placing food into the mouth (entry of food in the digestive system),
It also aids the initial chemical digestion of food as it contains the enzyme amylase, responsible for breaking carbohydrates into sugars. [ 15 ] [ 16 ] Sensation : The oral mucosa is richly innervated, meaning it is a very good at sensing pain, touch, temperature and taste.