Diseases of the adrenal gland diseases adrenal cortex
Endocrinology / / April 29, 2016
Different groups of adrenal hormones are produced in different zones of the adrenal cortex.Cortisol and corticosterone synthesis occurs mainly in the beam area of the adrenal cortex.Corticosterone is produced in glomerular zone, being a precursor of aldosterone.Sex hormones and 17-keto steroids are produced mainly in the area of the mesh.However, Symington et al. Suggest that the beam and the net area functionally constitute a single system, with mesh zones cells produce androgens, and glucocorticoid.Aldosterone is synthesized in the zona glomerulosa.Corticosteroids are formed from cholesterol in the adrenal glands, and may acetate directly, bypassing the step of cholesterol.
scheme kortikosteooidov biosynthesis (main path)
corticosteroid biosynthesis occurs with the participation of specific enzymes - hydroxylases and dehydrogenases.These specific enzyme systems, including those co-factors as difosfopiridinnukleotid (DPN) and trifosfopiridinnukleotid (ESRD), localized in the mitochondria, micr
The adult human adrenal glands secrete a day 15-30 mg hydrocortisone, 2-5 mg of corticosterone, aldosterone 15-150 micrograms.
cortex stimulation in conditions of adrenal secretion of adrenocorticotropic hormone cortisol can rise by 5-10 times.
Cortisol circulates in the blood predominantly in protein-bound form.Protein specific binding corticosteroids, in particular hydrocortisone, is a 1-glycoprotein from group a-1 globulin-called transcortin.Transcortin synthesis occurs in the liver.Also transcortin, a much smaller amount of cortisol binds serum albumin.
relative amount of free cortisol is increased with an increase in circulating levels of the hormone in the blood.
When treating estrogen due to increased transcortin synthesis in the liver and increase of its binding capacity, the overall level of cortisol in the blood is enhanced by the bound cortisol.The same occurs in the later stages of pregnancy, apparently due to increased estrogen levels during this period.Increased binding of hydrocortisone transcortin also observed in some diseases, such as rheumatoid arthritis.Compound
cortisol with proteins apparently contributes to the greater solubility of hormone and provides its transport to the tissues.In conjunction with cortisol transcortin devoid of biological activity, is not subjected to metabolism in the liver;removing it from the body decreases.Cortisol is associated with transcortin is probably reserve that can be mobilized in case of insufficient incretion hormone of the adrenal cortex.
Other corticosteroids - corticosterone and aldosterone - hardly communicate transcortin.Aldosterone partly in connection with blood plasma albumin.
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cortisol half-life time in the body, as it is established by means oflabeled cortisol is 90 min.The main body in which the cortisol metabolism is the liver, although some reactions, such as cortisol into cortisone transition may occur outside the liver.cortisol Inactivation occurs not by breaking of the steroid ring, and by converting it into tetragidrosoedineniya tetrahydrocortisol and conjugation with glucuronic acid and (to a much lesser extent) with sulfuric and phosphoric acids.These compounds are highly soluble in water and are rapidly excreted in urine.Filter inactive cortisol conjugated compounds occurs freely in the kidney glomeruli, reabsorption in the tubules of their extremely small.A small portion of hydrocortisone - from 5 to 10% in the liver -prevraschaetsya 17-keto steroids - ketoetioholanolon-11 and B-11 gidroksiandrosteron.A small part of tetrahydrocortisol and tetragidrokortizona undergoes further transformations in the liver to form 20-A and 20-B-derivatives - tetragidrokortol and tetragidrokortolon.
metabolism of corticosterone is, in general, follow the same path as the exchange of cortisol, corticosterone but in more prevraschaetsyav kortolon, pregnandiol and pregnantriol, and from it are formed 17-keto steroids.Aldosterone
, as cortisol and corticosterone, inactivated in the liver, where it formed tetragidrosoedineniya accession glucuronic acid at the 3-carbon atom.Part of aldosterone is released in urine in unchanged form.
17-keto steroids are joined predominantly in the liver with sulfuric acid.