Biochem.docx - • Primary adrenal insufficiency, is a rare...

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Primaryadrenal insufficiency, is a rareendocrine disorderthat happens whenthe adrenalglandisn't able to produce enough of the hormones that the body needs,particularlyaldosteroneandcortisol.Thereasonit’s called “primary” is that the underlying problem is localized tothe adrenalglanditself, rather than a problem of a hormone that acts onthe adrenal glandor elsewherein the body.Theadrenal cortex has a high functional reserve, meaning that a small amount offunctional tissue can still do a pretty decent job of churning out enough of the hormonesto meet the body’s needs.In secondaryadrenal insufficiency, the problem is not with theadrenal glandsbut withthepituitary, which secretes insufficient ACTH and since ACTH onlyregulatescortisolproduction, in this case there’scortisoldeficiency, butaldosteronelevels arenormal.This can happen withpanhypopituitarism, when the entirepituitary glandis affected, and allthe hormones secreted by it are deficient.There’stertiaryadrenal insufficiency, where the problem originates withthehypothalamusand there’s insufficient CRH secretion.So once again, because there’s no CRH to stimulate thepituitaryto release ACTH, theadrenalglandswon’t producecortisol.And because CRH doesn’t influence its production,aldosteronelevels are normal.Aldosterone is part of a hormone family or axis which work together and arecalled therenin-angiotensin-aldosterone system.Together these hormones decrease potassium levels, increase sodium levels, andincrease blood volume andblood pressure.Through physiological processes it increases the blood pressure by increasing the blood volume.Cortisolis also needed in times of emotional and physicalstresslike arguing witha friend or fleeing from a pack of raccoons.In those situations, the hypothalamus—which is an almond-size structure which sits atthe base of the brain, releases corticotropin-releasing hormone is released from, andreceived by the pituitary gland, the pea-sized structure sitting just underneath thehypothalamus.
In response, the pituitary gland sends outadrenocorticotropic hormone, or ACTH, whichtravels through the blood to the zona fasciculata of the adrenal glands and signals cellsthere to releasecortisol.Cortisolis a lipid-soluble molecule, meaning it can mingle withfats, which allows it toeasily pass through theplasma membraneof cells and bind to the receptors inside.

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Term
Summer
Professor
mehrasa
Tags
Cortisol, Adrenal insufficiency

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