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Adrenal Glands - Anatomy & Physiology (view source)
Revision as of 15:15, 11 September 2008
, 15:15, 11 September 2008→Adrenal Cortex
===Adrenal Cortex===
===Adrenal Cortex===
* The Zona Glomerulosa secretes mineralocorticoids
The function of the cortex is to produce ''adrenocorticoid hormones''. The three zones each make a specific type of hormone:
* The Zona Fasciculata secretes glucocorticoids
* The Zona Glomerulosa secretes '''mineralocorticoids'''
* The Zona Reticularis secretes sex steroids
* The Zona Fasciculata secretes '''glucocorticoids'''
* The Zona Reticularis secretes sex steroids or '''androgens'''
They are formed from the esterified cholesterol that is stored in intracellular lipid droplets. Below is the steps of how the adrenocorticoid hormones are made from cholesterol.
1) The P450scc enzyme converts cholesterol to pregnenolone by the removal of a side chain. This is regulated by ACTH and is the rate determining step of adrenocorticoid hormone production. This occurs in the mitochondria.
2) Hydroxylation reactions occur in the mitochondria and endoplasmic reticulum converting pregnenolone into specific hormones. The location within the cortex determines the hormones produced.
'''Mineralocorticoids'''
These hormones regulate the mtabolism of inorganic ions, such sodium, potassium and chloride. Several hormones are produced but the most important is '''aldosterone'''.
It is formed in the zona glomerulosa by the conversion of pregnenolone to cortisol and then to corticosterone before finally becoming aldosterone. It circulates by binding to albumin and cortisol-binding globulin. It's plasma half-life is 20 minutes. It is eventually inactivated in the liver, where it binds to glucuronic acid and is excreted in bile and urine.
''Regulation and action'' - It's main regulators of synthesis and secretion are; '''Renin''' and extracellular concentrations of potassium ions. Its main action is upon renal regulation and electrolyte and fluid balance. These are fully explained within the '''[[Important Hormonal Regulators of the Kidney - Anatomy & Physiology|renin-angiotensin and aldosterone]] page.
==Histology of the Adrenal Glands==
==Histology of the Adrenal Glands==