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Angiotensin is a hormone which will be transformed from the predecessor of the serum globulin synthesized by a liver. Angiotensin is extremely important for hormonal a renin-angiotenzinovoy of system – systems which are responsible for the volume of blood and pressure in a human body.
Substance angiotensinogen belongs to the class of globulins, it consists from more, than 400 amino acids. Its production and release in blood is made by a liver constantly. Level of angiotensin can increase under the influence of angiotensin II, thyroid hormone, estrogen, plasma corticosteroids. When the blood pressure goes down, it works as the stimulating factor for production of a renin, its allocation in blood. This process starts angiotensin synthesis.
Angiotensin I and angiotensin II
Under the influence of a renin the following substance — angiotensin I is formed of angiotensinogen. This substance does not bear any biological activity, its leading role – to be a predecessor of angiotensin II. The last hormone already is active: it provides synthesis of Aldosteronum, narrows vessels. This system is a target for drugs which lower pressure, and also for a set of the inhibiting means which reduce concentration of angiotensin II.
Angiotensin role in an organism
This substance is a strong vasoconstrictor. It means that it narrows veins and arteries, and it, in turn, leads to increase in arterial pressure. Its such activity is provided thanks to chemical bonds which are formed at interaction of hormone with a special receptor. Also it is possible to distinguish aggregation of thrombocytes, regulation of adhesion and protrombotichesky effect from the functions relating to cardiovascular system. For arising in our organism feeling of thirst just this hormone answers. It causes increase in secretion of vasopressin in neurosecretory cells in such department of a brain as a hypothalamus, and also secretion of adrenocorticotropic hormone in a hypophysis. It leads to fast release of noradrenaline. Hormone Aldosteronum allocated by adrenal glands is thrown out blood just thanks to angiotensin. Plays an important role in maintenance of an electrolytic and water balance, renal hemodynamics. The sodium delay is provided with this substance thanks to its ability to influence proximal tubules. Generally, it is capable to catalyze reaction of glomerular filtering due to increase in pressure in kidneys and narrowings of renal efferent arterioles.
For determination of level of this hormone in blood usual blood test, as well as on any other hormones is made. Its surplus can testify to the increased concentration of estrogen, be observed when using oral contraceptive tablets and during pregnancy, after a binefrektomiya, the illness of Itsenko-Kushinga can be an illness symptom. The lowered level of angiotensin is observed at insufficiency of glucocorticoids, for example, at diseases of a liver, Addison's illness.