Category: Gastrointestinal System
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APUD cells (DNES cells)
APUD cells (DNES cells) constitute a group of apparently unrelated endocrine cells, which were named by the scientist A.G.E. Pearse, who developed the APUD concept in the 1960s based on calcitonin-secreting parafollicular C cells of dog thyroid. These cells share the common function of secreting a low molecular weight polypeptide hormone. There are several different types which secrete the hormones secretin, cholecystokinin and several others.…
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G cells or gastrin cells secrete gastrin. They works in conjunction with gastric chief cells and parietal cells. The peptide hormone bombesin also stimulates gastrin from G cells.
In anatomy, the G cell or gastrin cell, is a type of cell in the stomach and duodenum that secretes gastrin. It works in conjunction with gastric chief cells and parietal cells. G cells are found deep within the pyloric glands of the stomach antrum, and occasionally in the pancreas and duodenum. The vagus nerve innervates the G cells. Gastrin-releasing peptide is released by the post-ganglionic fibers of the vagus nerve onto G cells…
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Enterochromaffin-like cells (ECL cells) are neuroendocrine and enteroendocrine cells that aid in the production of gastric acid via the release of histamine
Enterochromaffin-like cells or ECL cells are a type of neuroendocrine cell found in the gastric glands of the gastric mucosa beneath the epithelium, in particular in the vicinity of parietal cells, that aid in the production of gastric acid via the release of histamine. They are also considered a type of enteroendocrine cell. Function ECL cells synthesize and secrete histamine. These cells are stimulated by the hormones gastrin (not depicted in…
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Enterochromaffin (EC) cells aka Kulchitsky cells
Enterochromaffin (EC) cells (also known as Kulchitsky cells) are a type of enteroendocrine cell, and neuroendocrine cell. They reside alongside the epithelium lining the lumen of the digestive tract and play a crucial role in gastrointestinal regulation, particularly intestinal motility and secretion. They were discovered by Nikolai Kulchitsky. EC cells modulate neuron signalling in the enteric nervous system (ENS) via the secretion of the neurotransmitter serotonin and other peptides.…
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Delta cells (δ-cells or D cells) are somatostatin-producing cells
Delta cells (δ-cells or D cells) can be found in the stomach, intestine and the pancreatic islets. Delta cells comprise ca 5% of the cells in the islets but may interact with many more islet cells than suggested by their low numbers. In rodents, delta-cells are located in the periphery of the islets; in humans the islet architecture is generally less organized and…
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HCO3 (bicarbonate)
In inorganic chemistry, bicarbonate (IUPAC-recommended nomenclature: hydrogencarbonate) is an intermediate form in the deprotonation of carbonic acid. It is a polyatomic anion with the chemical formula HCO3. Bicarbonate serves a crucial biochemical role in the physiological pH buffering system. The term “bicarbonate” was coined in 1814 by the English chemist William Hyde Wollaston. The name lives on as a trivial name. Chemical properties The bicarbonate ion (hydrogencarbonate ion) is an anion with the empirical formula HCO−3 and a molecular…
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Intrinsic factor (IF) and haptocorrin (transcobalamin I) are necessary for the absorption of vitamin B12
Intrinsic factor (IF), cobalamin binding intrinsic factor, also known as gastric intrinsic factor (GIF), is a glycoprotein produced by the parietal cells (in humans) or chief cells (in rodents) of the stomach. It is necessary for the absorption of vitamin B12 later on in the distal ileum of the small intestine. In humans, the gastric intrinsic factor protein is encoded by the CBLIFgene. Haptocorrin (transcobalamin I) is another glycoprotein secreted by the salivary glands which binds…
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Pepsinogens are mainly grouped in 5 different groups based on their primary structure
1. Pepsinogen A (also called pepsinogen I) 2. Pepsinogen B 3. Progastricsin (also called pepsinogen II and pepsinogen C) 4. Prochymosin (also called prorennin) 5. Pepsinogen F (also called pregnancy-associated glycoprotein).
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Goblet cells
Goblet cells are simple columnar epithelial cells that secrete gel-forming mucins, like mucin 5AC. The goblet cells mainly use the merocrine method of secretion, secreting vesicles into a duct, but may use apocrine methods, budding off their secretions, when under stress. The term goblet refers to the cell’s goblet-like shape. The apical portion is shaped like a cup, as it is distended by abundant mucus laden granules;…
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Gastric lipase
Gastric lipase, also known as LIPF, is an enzymatic protein that, in humans, is encoded by the LIPF gene. Function Gastric lipase is an acidic lipase secreted by the gastric chief cells in the fundic mucosa in the stomach. It has a pH optimum of 3–6. Gastric lipase, together with lingual lipase, comprise the two acidic lipases. These lipases, unlike alkaline lipases (such as pancreatic lipase), do not require bile acid or colipase for…
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Digestive enzymes
Digestive enzymes are a group of enzymes that break down polymeric macromolecules into their smaller building blocks, in order to facilitate their absorption into the cells of the body. Digestive enzymes are found in the digestive tracts of animals (including humans) and in the tracts of carnivorous plants, where they aid in the digestion of food, as well as inside cells,…
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Arginine
Arginine is the amino acid with the formula (H2N)(HN)CN(H)(CH2)3CH(NH2)CO2H. The molecule features a guanidino group appended to a standard amino acid framework. At physiological pH, the carboxylic acid is deprotonated (−CO2−) and both the amino and guanidino groups are protonated, resulting in a cation. Only the l-arginine (symbol Arg or R) enantiomer is found naturally. Arg residues are common components of proteins. It is encoded by the codons CGU, CGC,…
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Somatostatin
Not to be confused with Somatocrinin or Somatomedin. Somatostatin, also known as growth hormone-inhibiting hormone (GHIH) or by several other names, is a peptide hormone that regulates the endocrine system and affects neurotransmission and cell proliferation via interaction with G protein-coupled somatostatin receptors and inhibition of the release of numerous secondary hormones. Somatostatin inhibits insulin and glucagon secretion. “somatostatin”. Encyclopædia Britannica. Encyclopædia Britannica Online. Encyclopædia Britannica Inc., 2016. Web. 04 mag. 2016…
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Oxytocin
Oxytocin (Oxt or OT) is a peptide hormone and neuropeptide normally produced in the hypothalamus and released by the posterior pituitary. Gray’s Anatomy: The Anatomical Basis of Clinical Practice (41 ed.). Elsevier Health Sciences. 2015. p. 358. ISBN 978-0-7020-6851-5. It plays a role in social bonding, reproduction, childbirth, and the period after childbirth. Audunsdottir K, Quintana DS (2022-01-25). “Oxytocin’s dynamic role across the lifespan”. Aging Brain: 100028. doi:10.1016/j.nbas.2021.100028. ISSN 2589-9589. S2CID 246314607. Leng G, Leng RI (November 2021). “Oxytocin: A…
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Cholecystokinin aka pancreozymin notes
History Structure Function Gastrointestinal Digestion Satiety The effects of CCK vary between individuals. For example, in rats , CCK administration significantly reduces hunger in adult males, but is slightly less effective in younger subjects, and even slightly less effective in females. The hunger-suppressive effects of CCK also are reduced in obese rats. Fink H, Rex A, Voits M, Voigt…
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Gastrin
Gastrin is a peptide hormone that stimulates secretion of gastric acid (HCl) by the parietal cells of the stomach and aids in gastric motility. It is released by G cells in the pyloric antrum of the stomach, duodenum, and the pancreas. Gastrin binds to cholecystokinin B receptors to stimulate the release of histamines in enterochromaffin-like cells, and it induces the insertion of K+/H+ ATPase pumps into the apical membrane of parietal cells (which…
