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Encyclopedia > Parietal cell
Human parietal cells - stomach

Parietal cells (also called oxyntic cells) are the stomach epithelium cells which secrete gastric acid and intrinsic factor. Image File history File links Metadata Size of this preview: 800 × 600 pixelsFull resolution (2816 × 2112 pixel, file size: 2. ... Image File history File links Metadata Size of this preview: 800 × 600 pixelsFull resolution (2816 × 2112 pixel, file size: 2. ... Download high resolution version (987x1194, 199 KB)Diagram summarising control of stomach acid secretion. ... Download high resolution version (987x1194, 199 KB)Diagram summarising control of stomach acid secretion. ... In anatomy, the stomach is a bean-shaped hollow muscular organ of the gastrointestinal tract involved in the second phase of digestion, following mastication. ... This article is about the epithelium as it relates to animal anatomy. ... Drawing of the structure of cork as it appeared under the microscope to Robert Hooke from Micrographia which is the origin of the word cell being used to describe the smallest unit of a living organism Cells in culture, stained for keratin (red) and DNA (green) The cell is the... Gastric acid is, together with several enzymes and the intrinsic factor, one of the main secretions of the stomach. ... Intrinsic factor is a glycoprotein produced by the parietal cells of the stomach. ...

Contents

Acid production

Parietal cells produce gastric acid (hydrochloric acid) in response to histamine (via H2 receptors), acetylcholine (M3 receptors) and gastrin (CCK2 receptors). The histamine receptors act by increasing intracellular cAMP, whereas the muscarinic and gastrin receptors increase intracellular Ca2+ levels. Both cAMP and Ca2+ acts via protein kinases to increase the transport of acid into the stomach. Gastric acid is, together with several enzymes and the intrinsic factor, one of the main secretions of the stomach. ... The chemical compound hydrochloric acid is the aqueous (water-based) solution of hydrogen chloride gas (HCl). ... In biochemistry, a receptor is a protein on the cell membrane or within the cytoplasm or cell nucleus that binds to a specific molecule (a ligand), such as a neurotransmitter, hormone, or other substance, and initiates the cellular response to the ligand. ...


Parietal cells contain an extensive secretory network (called canaliculi) from which the HCl is secreted by active transport into the stomach. The enzyme hydrogen potassium ATPase (H+/K+ ATPase) is unique to the parietal cells and transports the H+ against a concentration gradient of about 3 million to 1. Sodium-Potassium pump, an example of Primary active transport secondary active transport Active transport (sometimes called active uptake) is the mediated transport of biochemicals, and other atomic/molecular substances, across membranes. ... Gastric hydrogen potassium ATPase also know as H+/K+ ATPase // Function and location The gastric hygrogen potassium ATPase or H+/K+ ATPase is the proton pump of the stomach and as such is the enzyme primarily responsible for the acidification of the stomach contents. ... For other uses, see Concentration (disambiguation). ...


Hydrochloric acid is formed in the following manner:

  • Hydrogen ions are formed from the dissociation of water molecules. The enzyme carbonic anhydrase converts one molecule of carbon dioxide and one molecule of water to a bicarbonate ion (HCO3-) and a hydrogen ion (H+).
  • The bicarbonate ion (HCO3-) is exchanged for a chloride ion (Cl-) on the basal side of the cell and the bicarbonate diffuses into the blood.
  • Potassium (K+) and chloride (Cl-) ions diffuse into the canaliculi.
  • Hydrogen ions are pumped out of the cell into the canaliculi in exchange for potassium ions, via the H+/K+ ATPase.

The resulting highly-acidic environment causes proteins from food to unfold (or denature), exposing the peptide bonds that link together amino acids. HCl also activates pepsin, allowing it to help digestion by breaking specific peptide bonds, a process known as proteolysis. Ribbon diagram of the enzyme TIM, surrounded by the space-filling model of the protein. ... Carbonic anhydrase (carbonate dehydratase) is a family of metalloenzymes (enzymes that contain one or more metal atoms as a functional component of the enzyme) that catalyze the rapid interconversion of carbon dioxide and water into carbonic acid, protons, and bicarbonate ions. ... Carbon dioxide is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. ... For baking soda, see Sodium bicarbonate In inorganic chemistry, a bicarbonate (IUPAC-recommended nomenclature: hydrogencarbonate) is an intermediate form in the deprotonation of carbonic acid. ... General Name, symbol, number potassium, K, 19 Chemical series alkali metals Group, period, block 1, 4, s Appearance silvery white Standard atomic weight 39. ... Gastric hydrogen potassium ATPase also know as H+/K+ ATPase // Function and location The gastric hygrogen potassium ATPase or H+/K+ ATPase is the proton pump of the stomach and as such is the enzyme primarily responsible for the acidification of the stomach contents. ... A representation of the 3D structure of myoglobin, showing coloured alpha helices. ... Irreversible egg protein denaturation and loss of solubility, caused by the high temperature (while cooking it) Denaturation is the alteration of a protein or nucleic acids shape through some form of external stress (for example, by applying heat, acid or alkali), in such a way that it will no... A peptide bond is a chemical bond that is formed between two molecules when the carboxyl group of one molecule reacts with the amino group of the other molecule, releasing a molecule of water (H2O). ... In chemistry, an amino acid is any molecule that contains both amino and carboxylic acid functional groups. ... Pepsin is a digestive protease (EC 3. ... Proteolysis is the directed degradation (digestion) of proteins by cellular enzymes called proteases or by intramolecular digestion. ...


Parietal cells secrete acid in response to three types of stimuli: Secretion is the process of segregating, elaborating, and releasing chemicals from a cell, or a secreted chemical substance or amount of substance. ... In physiology, a stimulus is a detectable change in the internal or external environment. ...

  • H2 histamine receptors (most significant contribution)
  • parasympathetic activity via the Vagus nerve
  • gastrin (least significant contribution, but note that histamine secretion by ECL cells is due in part to gastrin)

Upon stimulation, adenylate cyclase is activated within the parietal cells. This increases intracellular cyclic AMP, which leads to activation of protein kinase A. Protein kinase A phosphorylates proteins involved in the transport of H+/K+ ATPase from the cytoplasm to the cell membrane. This causes resorption of K+ ions and secretion of H+ ions. The pH of the secreted fluid can fall 'by' 0.8. This article or section does not cite any references or sources. ... Anatomy and Physiology of the A.N.S. In contrast to the voluntary nervous system, the involuntary or autonomic nervous system is responsible for homeostasis, maintaining a relatively constant internal environment by controlling such involuntary functions as digestion, respiration, and metabolism, and by modulating blood pressure. ... The vagus nerve (also called pneumogastric nerve or cranial nerve X) is the tenth of twelve paired cranial nerves, and is the only nerve that starts in the brainstem (within the medulla oblongata) and extends, through the jugular foramen, down below the head, to the abdomen. ... In humans, gastrin is a hormone that stimulates secretion of gastric acid by the stomach. ... Epinephrine binds its receptor, that associates with an heterotrimeric G protein. ... Structure of cAMP cAMP represented in three ways, the left with sticks-representation, the middle with structure formula, and the right with space filled representation. ... Gastric hydrogen potassium ATPase also know as H+/K+ ATPase // Function and location The gastric hygrogen potassium ATPase or H+/K+ ATPase is the proton pump of the stomach and as such is the enzyme primarily responsible for the acidification of the stomach contents. ... Look up cell membrane in Wiktionary, the free dictionary. ... For other uses, see PH (disambiguation). ...


Intrinsic factor

Parietal cells also produce intrinsic factor. Intrinsic factor is required for the absorption of vitamin B12 in the diet. Intrinsic factor is a glycoprotein produced by the parietal cells of the stomach. ... Cyanocobalamin is a compound that is metabolized to a vitamin in the B complex commonly known as vitamin B12 (or B12 for short). ...


Diseases of parietal cells

  • Peptic ulcers can result from over-acidity in the stomach. Antacids can be used to enhance the natural tolerance of the gastric lining. Antimuscarinic drugs such as pirenzepine or H2 antihistamines can reduce acid secretion. Proton pump inhibitors are more potent at reducing gastric acid production since that is the final common pathway of all stimulation of acid production.
  • In pernicious anemia, autoantibodies directed against parietal cells or intrinsic factor cause a reduction in vitamin B12 absorption. It can be treated with injections of replacement vitamin B12 (hydroxocobalamin or cyanocobalamin).
  • Achlorhydria is another autoimmune disease of the parietal cells. The damaged parietal cells are unable to produce the required amount of gastric acid. This leads to an increase in gastric pH, impaired digestion of food and increased risk of gastroenteritis.

A benign gastric ulcer (from the antrum) of a gastrectomy specimen. ... An anticholinergic agent is a member of a class of pharmaceutical compounds which serve to reduce the effects mediated by acetylcholine in the central nervous system and peripheral nervous system. ... This does not cite any references or sources. ... An antihistamine is a drug which serves to reduce or eliminate effects mediated by histamine, an endogenous chemical mediator released during allergic reactions, through action at the histamine receptor. ... Proton pump inhibitors (or PPIs) are a group of drugs whose main action is pronounced and long-lasting reduction of gastric acid production. ... Pernicious anemia (also known as Biermers anaemia or Addisons anaemia or Addison-Biermer anaemia) is a form of megaloblastic anaemia due to vitamin B12 deficiency dependent on impaired absorption of vitamin B12 in the setting of atrophic gastritis, and more specifically of loss of gastric parietal cells. ... An autoantibody is an antibody (a type of protein) manufactured by the immune system that is directed against one or more of the individuals own proteins. ... Achlorhydria or hypochlorhydria is decreased production of gastric acid by the stomach. ... Autoimmune diseases arise from an overactive immune response of the body against substances and tissues normally present in the body. ... Gastroenteritis involves diarrhea or vomiting, with noninflammatory infection of the upper small bowel, or inflammatory infection of the colon, both part of the gastrointestinal tract. ...

See also

In general, a Chief cell (or a zymogenic cell) is a cell which releases a precursor enzyme. ...

External links

  • Illustration of Chief cells and Parietal cells at anatomyatlases.org
  • The Parietal Cell: Mechanism of Acid Secretion at vivo.colostate.edu
  • Histology at BU 11303loa - Digestive System: Alimentary Canal: fundic stomach, gastric glands, lumen"
  • MeSH Gastric+Parietal+Cells
  • Physiology at MCG 6/6ch4/s6ch4_8
  • Physiology at MCG 6/6ch4/s6ch4_14
  • Parietal cell antibody
  • Antibody to GPC

For similarly-named academic institutions, see Boston (disambiguation). ... Medical Subject Headings (MeSH) is a huge controlled vocabulary (or metadata system) for the purpose of indexing journal articles and books in the life sciences. ... In 1828 the Medical Academy of Georgia was chartered by the state of Georgia with plans to offer a single course of lectures leading to a bachelors degree. ... In 1828 the Medical Academy of Georgia was chartered by the state of Georgia with plans to offer a single course of lectures leading to a bachelors degree. ...

References

  • Review of Medical Physiology, William F. Ganong, 20th Edition, 2001, McGraw-Hill, ISBN 0-07-112064-5 pp467-470

  Results from FactBites:
 
The Parietal Cell: Mechanism of Acid Secretion (853 words)
As a consequence, the parietal cell and the mechanisms it uses to secrete acid have been studied extensively, leading to development of several drugs useful for suppressing acid secretion.
Histamine from enterochromaffin-like cells may well be the primary modulator, but the magnitude of the stimulus appears to result from a complex additive or multiplicative interaction of signals of each type.
Histamine's effect on the parietal cell is to activate adenylate cyclase, leading to elevation of intracellular cyclic AMP concentrations and activation of protein kinase A (PKA).
  More results at FactBites »

 
 

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