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Encyclopedia > Gastrin

In humans, gastrin is a hormone that stimulates secretion of gastric acid by the stomach. It is released by G cells in the stomach and duodenum. A hormone (from Greek horman - to set in motion) is a chemical messenger from one cell (or group of cells) to another. ... Gastric acid is, together with several enzymes and the intrinsic factor, one of the main secretions of the stomach. ... In anatomy, the stomach (in ancient Greek στόμαχος) is an organ in the gastrointestinal tract used to digest food. ... In medicine, the G cell is a type of cell in the stomach that secrets gastrin. ... In anatomy of the digestive system, the duodenum is a hollow jointed tube connecting the stomach to the jejunum. ...

Contents


Physiology

Genetics

The GAS gene is located on the long arm of the seventh chromosome (17q21).


Synthesis and release

Gastrin is a linear peptide hormone produced by G cells that are located mainly in the antrum of the stomach. It is secreted into the bloodstream. Gastrin is found primarily in three forms: gastrin-34 ("big gastrin"), gastrin-17 ("little gastrin"), and gastrin-14 ("minigastrin"). The numbers refer to the amino acid count. Peptide hormones are a class of peptides that are secreted into the blood stream and have endocrine functions in living animals. ... In medicine, the G cell is a type of cell in the stomach that secrets gastrin. ... In Biology, Antrum is a general term for a cavity or chamber which may have specific meaning in reference to certain organs or sites in the body. ... In anatomy, the stomach (in ancient Greek στόμαχος) is an organ in the gastrointestinal tract used to digest food. ... An amino acid residue is what is left of an amino acid once a molecule of water has been lost (an H+ from the nitrogenous side and an OH- from the carboxylic side) in the formation of a peptide bond. ...


Gastrin is released in response to certain stimuli. These include: stomach distension, vagal stimulation (mediated by the neurocrine bombesin, or GRP in the human), the presence of partially digested proteins especially amino acids and hypercalcemia. Gastrin release is inhibited by the presence of acid (primarily the secreted HCl) in the stomach (a case of negative feedback). Somatostatin also inhibits the release of gastrin, along with secretin, GIP, VIP, glucagon and calcitonin. The vagus nerve (or pneumogastric nerve) 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. ... Neurocrine Biosciences NASDAQ: NBIX is a biopharmaceutical company founded in 1992 and located in San Diego, California. ... Bombesin is a 14 amino acid peptide originally isolated from the skin of a frog. ... Gastrin releasing peptide (GRP) is released by the post-ganglionic fibres of the vagus nerve which innervate the G cells of the stomach and stimulate them to release gastrin. ... Digestion is the process whereby a biological entity processes a substance, in order to chemically convert the substance into nutrients. ... A representation of the 3D structure of myoglobin, showing coloured alpha helices. ... In chemistry, an amino acid is any molecule that contains both amino and carboxylic acid functional groups. ... Hypercalcaemia is an elevated calcium level in the blood. ... For other uses, see Acid (disambiguation). ... Negative feedback is the process of feeding back to the input a part of a systems output, so as to reverse the direction of change of the output. ... Somatostatin is a hormone. ... Secretin is a peptide hormone produced in the S cells of the duodenum. ... Glucagon ball and stick model Glucagon is a 29-amino acid polypeptide acting as an important hormone in carbohydrate metabolism. ... Calcitonin is a a 32 amino acid polypeptide hormone that is produced in humans primarily by the C cells of the thyroid, and in many other animals in the ultimobranchial body. ...


Function

The presence of gastrin stimulates parietal cells of the stomach to secrete hydrochloric acid (HCl)/gastric acid. This is done either directly or indirectly:
- Directly: binds onto CCK-B receptors on parietal cells stimulating them to secrete H+ ions.
- Indirectly: binds onto CCK-B receptors on ECL cells in the stomach, which then responds by releasing histamine, which in turn acts in a paracrine manner on parietal cells stimulating them to secrete H+ ions.
It also causes chief cells to secrete pepsinogen, the zymogen (inactive) form of the digestive enzyme pepsin. Pepsinogen is converted to pepsin in a low pH environment, and the HCl provides a suitable environment for its activity. It can also increase antral muscle mobility and trophic effect on GI tract. Gastrin has also been shown to induce production of pancreatic enzymes by acinar cells. Parietal cells (also called oxyntic cells) are cells located in the stomach epithelium. ... Secretion is the process of segregating, elaborating, and releasing chemicals from a cell, or a secreted chemical substance or amount of substance. ... The chemical substance hydrochloric acid is the aqueous (water-based) solution of hydrogen chloride (HCl) gas. ... In general, a chief cell (or a zymogenic cell) is a cell which releases a precursor enzyme. ... Pepsin is a protease, a digestive enzyme that degrades food proteins in the stomach; the other important digestive enzymes are trypsin and chymotrypsin. ... A zymogen or a proenzyme, is an inactive enzyme precursor. ... Ribbon diagram of the enzyme TIM. TIM is catalytically perfect, meaning its conversion rate is limited, or nearly limited to its substrate diffusion rate. ... This article is in need of attention from an expert on the subject. ... The correct title of this article is pH. The initial letter is capitalized due to technical restrictions. ... The pancreas is an organ that serves two exocrine - it produces pancreatic juice containing digestive enzymes. ... The pancreas is an organ in the digestive system that serves two major functions: exocrine - it produces pancreatic juice containing digestive enzymes. ...


Factors influencing secretion

Gastric lumen:

  • Stimulatory factors: dietary protein and amino acids, high blood calcium. (i.e. during the gastric phase)
  • Inhibitory factor: acidity (pH below 3) - a negative feedback mechanism, exerted via the release of somatostatin from D cells in the stomach, which inhibits gastrin and histamine release.

Paracrine: Hypercalcaemia is an elevated calcium level in the blood. ...

  • Stimulatory factor: bombesin
  • Inhibitory factor: somatostatin - acts on somatostatin-2 receptors on G cells. in a paracrine manner via local diffusion in the intercellular spaces, but also systemically through its release into the local mucosal blood circulation; it inhibits acid secretion by acting on parietal cells.

Nervous: Bombesin is a 14 amino acid peptide originally isolated from the skin of a frog. ... Somatostatin is a hormone. ...

  • Stimulatory factors: Beta-adrenergic agents, cholinergic agents, gastrin-releasing peptide (GRP)

Circulation:

Adrenaline redirects here. ... Gastric inhibitory peptide (GIP) is a gastrointestinal hormone secreted by the duodenum. ... Secretin is a peptide hormone produced in the S cells of the duodenum. ... Somatostatin is a hormone. ... Glucagon ball and stick model Glucagon is a 29-amino acid polypeptide acting as an important hormone in carbohydrate metabolism. ... Calcitonin is a a 32 amino acid polypeptide hormone that is produced in humans primarily by the C cells of the thyroid, and in many other animals in the ultimobranchial body. ...

Role in disease

In the Zollinger-Ellison syndrome, gastrin is produced at excessive levels, often by a gastrinoma (gastrin-producing tumor, mostly benign) of the antrum or the pancreas. To investigate for hypergastrinemia (high blood levels of gastrin), a "pentagastrin test" can be performed. Zollinger-Ellison syndrome is a disorder where increased levels of the hormone gastrin are produced, causing the stomach to produce excess hydrochloric acid. ... In humans, gastrin is a hormone that stimulates secretion of gastric acid by the stomach. ... In Biology, Antrum is a general term for a cavity or chamber which may have specific meaning in reference to certain organs or sites in the body. ... The pancreas is an organ that serves two exocrine - it produces pancreatic juice containing digestive enzymes. ...


External link

Hormones and endocrine glands -

Hypothalamus: GnRH - TRH - CRH - GHRH - somatostatin - dopamine | Posterior pituitary: vasopressin - oxytocin | Anterior pituitary: GH - ACTH - TSH - LH - FSH - prolactin - MSH - endorphins - lipotropin The Mendelian Inheritance in Man project is a database that catalogues all the known diseases with a genetic component, and - when possible - links them to the relevant genes in the human genome. ... A hormone (from Greek horman - to set in motion) is a chemical messenger from one cell (or group of cells) to another. ... An endocrine gland is one of a set of internal organs involved in the secretion of hormones into the blood. ... In the anatomy of mammals, the hypothalamus is a region of the brain located below the thalamus, forming the major portion of the ventral region of the diencephalon and functioning to regulate certain metabolic processes and other autonomic activities. ... Gonadotropin-releasing hormone 1 (GNRH1 also called LHRH) is a peptide hormone responsible for the release of FSH and LH from the anterior pituitary. ... Thyrotropin-releasing hormone (TRH) is a tripeptide hormone that stimulates the release of TSH and prolactin by the anterior pituitary. ... Corticotropin-releasing hormone (CRH), also called corticotropin-releasing factor (CRF) or corticoliberin, is a polypeptide hormone involved in the stress response. ... Growth hormone-releasing hormone (GHRH), also known as growth hormone-releasing factor (GRF or GHRF), is a 44-amino acid peptide hormone produced in the arcuate nucleus of the hypothalamus. ... Somatostatin is a hormone. ... Dopamine is a chemical naturally produced in the body. ... The posterior pituitary (also called the neurohypophysis) comprises the posterior lobe of the pituitary gland and is part of the endocrine system. ... Arginine vasopressin (AVP), also known as argipressin or antidiuretic hormone (ADH), is a human hormone that is mainly released when the body is low on water; it causes the kidneys to conserve water by concentrating the urine and reducing urine volume. ... Oxytocin is a hormone, found in mammals, which in humans is released mainly after stimulation of the nipples or distention of the vagina and which facilitates birth and breastfeeding. ... The anterior pituitary (also called the adenohypophysis) comprises the anterior lobe of the pituitary gland and is part of the endocrine system. ... Growth hormone Growth hormone is a polypeptide hormone synthesised and secreted by the anterior pituitary gland which stimulates growth and cell reproduction in humans and other vertebrate animals. ... Adrenocorticotropic hormone (ACTH or corticotropin) is a polypeptide hormone synthesised (from POMC, pre-opiomelanocortin) and secreted from corticotropes in the anterior lobe of the pituitary gland in response to the hormone corticotropin-releasing hormone (CRH) released by the hypothalamus. ... Thyroid-stimulating hormone (also known as TSH or thyrotropin) is a hormone synthesised and secreted by thyrotrope cells in the anterior pituitary gland which regulates the endocrine function of the thyroid gland. ... Luteinizing hormone (LH) is a hormone synthesised and secreted by gonadotropes in the anterior lobe of the pituitary gland. ... Follicle stimulating hormone Follicle stimulating hormone (FSH) is a hormone synthesised and secreted by gonadotropes in the anterior pituitary gland. ... Prolactin is a peptide hormone synthesised and secreted by lactotrope cells in the adenohypophysis (anterior pituitary gland). ... Melanocyte-stimulating hormone (MSH) is a peptide hormone produced by cells in the intermediate lobe of the pituitary gland. ... Endorphins are endogenous opioid biochemical compounds. ...


Thyroid: T3 and T4 - calcitonin | Parathyroid: PTH | Adrenal medulla: epinephrine - norepinephrine | Adrenal cortex: aldosterone - cortisol - DHEA | Pancreas: insulin - glucagon - somatostatin | Ovary: estradiol - progesterone - inhibin - activin | Testis: testosterone - AMH - inhibin | Pineal gland: melatonin | Kidney: renin - EPO - calcitriol - prostaglandin | Heart atrium: ANP The thyroid hormones, thyroxine (T4) and triiodothyronine (T3), are tyrosine-based hormones produced by the thyroid gland. ... Calcitonin is a a 32 amino acid polypeptide hormone that is produced in humans primarily by the C cells of the thyroid, and in many other animals in the ultimobranchial body. ... Categories: Anatomy stubs | Endocrine system ... Parathyroid hormone (PTH) is secreted by the parathyroid glands as a polypeptide containing 84 amino acids. ... Grays Fig. ... Adrenaline redirects here. ... Norepinephrine or noradrenaline is a catecholamine and a phenethylamine with chemical formula C8H11NO3. ... Grays Fig. ... Aldosterone is a steroid hormone synthesized from cholesterol by the enzyme aldosterone synthase. ... Cortisol is a corticosteroid hormone that is involved in the response to stress; it increases blood pressure and blood sugar levels and suppresses the immune system. ... It has been suggested that this article or section be merged with Prasterone. ... The pancreas is an organ that serves two exocrine - it produces pancreatic juice containing digestive enzymes. ... Insulin is not chemically related to inulin; the similarities in name do not relate to any similarity in form or function. ... Glucagon ball and stick model Glucagon is a 29-amino acid polypeptide acting as an important hormone in carbohydrate metabolism. ... Somatostatin is a hormone. ... Human female internal reproductive anatomy Ovaries are egg-producing reproductive organs found in female organisms. ... Estradiol (17-beta estradiol) (also oestradiol) is a sex hormone. ... Progesterone is a C-21 steroid hormone involved in the female menstrual cycle, pregnancy (supports gestation) and embryogenesis of humans and other species. ... Inhibin is a peptide that is an inhibitor of FSH synthesis and secretion and participates in the regulation of the menstrual cycle. ... Activin is a peptide that enhances FSH synthesis and secretion and participates in the regulation of the menstrual cycle. ... Human male anatomy The testicles, known medically as testes (singular testis), are the male generative glands in animals. ... Testosterone is a steroid hormone from the androgen group. ... Anti-Müllerian hormone (AMH) is a dimeric glycoprotein that inhibits the development of the Müllerian ducts in a male embryo. ... Inhibin is a peptide that is an inhibitor of FSH synthesis and secretion and participates in the regulation of the menstrual cycle. ... Diagram of pituitary and pineal glands. ... Structuring urgently requested // Definition Melatonin, 5-methoxy-N-acetyltryptamine, is a hormone found in all living creatures that have been studied from algae [1] to humans, at levels that vary in a diurnal cycle. ... Human kidneys viewed from behind with spine removed The kidneys are bean-shaped excretory organs in vertebrates. ... Renin, also known as angiotensinogenase, is a circulating enzyme (EC 3. ... Erythropoietin Erythropoietin (or EPO) is a glycoprotein hormone that is a growth factor for erythrocyte (red blood cell) precursors in the bone marrow. ... Vitamin D is a fat soluble vitamin that contributes to the maintenance of normal levels of calcium and phosphorus in the bloodstream. ... Chemical structure of prostaglandin E1 (PGE1). ... In anatomy, the atrium (plural: atria) is the blood collection chamber of a heart. ... Atrial natriuretic factor (ANF), atrial natriuretic peptide (ANP) or atriopeptin, is a polypeptide hormone involved in the homeostatic control of body water and sodium. ...


Stomach: gastrin | Duodenum: CCK - GIP - secretin - motilin - VIP | Ileum: enteroglucagon | Liver: IGF-1 In anatomy, the stomach (in ancient Greek στόμαχος) is an organ in the gastrointestinal tract used to digest food. ... In anatomy of the digestive system, the duodenum is a hollow jointed tube connecting the stomach to the jejunum. ... Cholecystokinin (from Greek chole, bile; cysto, sac; kinin, move; hence, move the bile-sac (gall bladder)) is a peptide hormone of the gastrointestinal system responsible for stimulating the digestion of fat and protein. ... Gastric inhibitory peptide (GIP) is a gastrointestinal hormone secreted by the duodenum. ... Secretin is a peptide hormone produced in the S cells of the duodenum. ... Motilin is a polypeptide hormone secreted by the small intestine that increases gastrointestinal motility and stimulates the production of pepsin. ... VIP is a peptide hormone containing 28 amino acid residues. ... Grays Fig. ... An editor has expressed a concern that the topic of this article may be unencyclopedic. ... The liver is the largest internal organ of the human body. ... The insulin-like growth factors (IGFs) are polypeptides with high sequence similarity to insulin. ...


Placenta: hCG - HPL - estrogen - progesterone The placenta is an ephemeral (temporary) organ present only in female placental mammals during gestation (pregnancy). ... Human chorionic gonadotropin (hCG) is a peptide hormone produced in pregnancy, that is made by the embryo soon after conception and later by the trophoblast (part of the placenta). ... Human placental lactogen (HPL), also called human chorionic somatomammotropin, is a polypeptide placental hormone. ... Estrogens (also oestrogens) are a group of steroid compounds, named for their importance in the oestrus cycle, functioning as the primary female sex hormone. ... Progesterone is a C-21 steroid hormone involved in the female menstrual cycle, pregnancy (supports gestation) and embryogenesis of humans and other species. ...


Adipose tissue: leptin Adipose tissue is an anatomical term for loose connective tissue composed of adipocytes. ... Leptin is a 16 kDa protein hormone that plays a key role in regulating energy intake and energy expenditure (appetite and metabolism). ...


  Results from FactBites:
 
Gastrin - boo (655 words)
Gastrin is the major hormone that regulates acid secretion in the stomach. A gastrin test measures the amount of gastrin in the blood.
Gastrin is a hormone produced by specialized cells in the stomach.
Small amounts of gastrin may also be produced by the pancreas and possibly the intestines.
Gastrin (0 words)
Gastrin is synthesized in G cells, which are located in gastric pits, primarily in the antrum region of the stomach and binds receptors found predominantly on parietal and enterochromaffin-like cells.
Gastrin is a linear peptide that is synthesized as a preprohormone and is post-translationally cleaved to form a family of peptides with identical carboxytermini.
Stimulation of ECL cells by gastrin leads to histamine release, and histamine binding to H2 receptors on parietal cells is necessary for full-blown acid secretion.
  More results at FactBites »


 

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