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Tuesday, December 23, 2014

Antidiuretic Hormone - ADH Hormone Definition

What is Antidiuretic hormone ( ADH )?

Antidiuretic hormone (ADH) or vasopressin is a hormone and a neurotransmitter. It is a cyclic nonapeptide which is composed of nine amino acids. Structurally it seems very on oxytocin. It is produced in the body by the hypothalamus and issued via neural pathways in the posterior lobe of the pituitary gland (the neurohypophysis) from which it enters the bloodstream. The release of ADH is regulated by osmotic receptors in the hypothalamus and blood pressure receptors in the heart, the pulmonary vasculature, the Carotid sinus, and by the presence of angiotensin II.

ADH as hormone

ADH plays an important role in the absorption of water in the distal tubule and collecting duct in the kidney. The V2 receptors of the kidneys serve as a binding site for ADH. By stimulating waterresorptie makes ADH ensure that less water enters the urine. As a result, the osmolality of urine is raised and lowered, the osmolality of the blood. ADH also has a vasoconstrictive effect (hence the name vasopressin).

ADH as a neurotransmitter

ADH plays a role in aggression and in the regulation of blood pressure and body temperature. May also play a role in the formation of memories.

ADH is secreted by the hypothalamus in a manner controlled by the biological clock in the brains.

ADH and social behavior

ADH plays a major role in several aspects of social behavior.

Dr. Ariel Knafo of the University of Jerusalem has found a link between the production of ADH and generosity. The study was done on 203 subjects, everyone got 12 dollars and could determine whether he / she loved everything or gave it away to another anonymous subject. Of all the subjects, the DNA was checked. The test showed that the subjects who AVPR1a variant of the ADH gene had an average of 50% gave away more money than those with a different variant of that gene. The AVPR1a variant has a longer promoter, this gene will be depreciated more and more there is ADH release.

RDA also plays a big role in monogamy. The production of ADH is in monogamous species much higher than species are polygamous or promiscuous. This mechanism appears to be again in the evolution have been invented several times because it is the same between non-related species. To determine whether RDA is the only determining factor is Larry Young conducted an experiment in which was increased by genetic modification, production of ADH in the grassland vole. The grass is naturally promiscuous vole, but the modified mice were in love (or any animal equivalent) and remained faithful to their partner. RDA appears to have been the determining factor.

ADH medical

In the absence of antidiuretic hormone enters a central diabetes insipidus in which the patient can not hold water well (polyuria) and must drink a lot (polydipsia) (sometimes 10-20 gallons per day or more) to prevent dehydration (dehydration). A lack of ADH can also be caused by consuming alcohol and caffeine. Hence one has to pee a lot and often (much) coffee, tea, cola drinks or alcohol is drunk. One speaks of a nephrogenic diabetes insipidus as the V2 receptors in the kidneys are absent, as the receptors the RDA can not bind properly or if the receptors are not working properly.

When excess ADH keep patient waterproof with weight gain, hyponatremia and edema occur. This sometimes occurs in people who have certain lung tumors. One speaks of SIADHS (Syndrome of Inappropriate ADH Secretion).

If you suspect a lack or excess of ADH can ADH in the clinical chemistry laboratory are measured in blood plasma. The osmolality of the blood plasma and the urine is therefore always be determined.

ADH and substances with similar effects are sometimes used as a treatment for bedwetting. Care needs to be taken to ensure that these resources be taken just before bedtime to prevent water retention during the day. A side effect may be that the blood pressure greatly increases.

ADH also has a negative effect on the kidneys and include associated with renal function decline in patients with diabetes and polycystic kidney disease (ADPKD).

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