Cholesterol Synthesis of the different 孕烯醇酮 steroids is not uniformly pregnenolone distributed through the cortex 17羟孕烯醇酮 Progesterone 17-hydroxypregnenolone The outermost group of cells (zona glomerulosa) synthesizes 17-hydroxyprogesterone aldosterone, but essentially no cortisol nor androgens, Aldosterone Cortisol Androgens because those cells do not express the enzyme 17. Ipha-hydroxylase which is necessary for synthesis of Steroid Representative Effects 17-hydroxypregnenolone and Nat,K+ and water 17-hydroxyprogesterone Mineralocorticoids Aldosterone homeostasis That enzyme is however Glucocorticoids Cortisol Glucose homeostasis present in cells of the inner and many others zones of the cortex( zonae fasiculata and reticularis Sex steroid androgens which are the major sites of cortisol production
Steroid Representative Effects Mineralocorticoids Aldosterone Na+, K+ and water homeostasis Glucocorticoids Cortisol Glucose homeostasis and many others Sex steroid Androgens Synthesis of the different steroids is not uniformly distributed through the cortex. The outermost group of cells (zona glomerulosa) synthesizes aldosterone, but essentially no cortisol nor androgens, because those cells do not express the enzyme 17- alpha-hydroxylase which is necessary for synthesis of 17-hydroxypregnenolone and 17-hydroxyprogesterone. That enzyme is however present in cells of the inner zones of the cortex (zonae fasiculata and reticularis), which are the major sites of cortisol production. 17羟孕烯醇酮 孕烯醇酮
The Adrenal Glands- Production of hormones Adrenal corte RAS and high K+ concentrations asterone stimulate release ona glomerulosa Androgens W(的 Epinephrine Aldosterone adosterone Androgens
The Adrenal Glands - Production of Hormones
Mineralocorticoids Aldosterone: the most common mineralocorticoid accounts for about 90% of all mineralocorticoid activity About 60% are bound to plasma proteins half life is about 20 min Aldosterone increases Na+ retention in kidney, sweat glands, and salivary glands, which also increases water retention Increases K+ and H+ secretion in kidney Save Nat, lose K: Renal reabsorption of Nat in the principal cells of the collecting tubules, the distal tubules and collecting ducts; excretion of K and hydrogen ions in the distal tubules and collecting ducts
Mineralocorticoids • Aldosterone: the most common mineralocorticoid, accounts for about 90% of all mineralocorticoid activity • About 60% are bound to plasma proteins, half life is about 20 min • Aldosterone increases Na+ retention in kidney, sweat glands, and salivary glands, which also increases water retention • Increases K+ and H+ secretion in kidney • Save Na+ , lose K+ : Renal reabsorption of Na+ in the principal cells of the collecting tubules, the distal tubules and collecting ducts; excretion of K+ and hydrogen ions in the distal tubules and collecting ducts
Regulation of aldosterone secretion Increased K; Increased activity of Renin-angiotensin system; Increased sodium -through renin; ACTH Lⅳ er Juxtaglomerular apparatus of kidney Increased fluid yo lume Angiotensinogen Renin negative and blood pressure feedback Angiotensin I Adrenal cortex Angiotensin II Aldosterone Increases Nat and water A reabsorption in convoluted tubules of kidney vasoconstniction ACTH
Regulation of aldosterone secretion Increased K; Increased activity of Renin-angiotensin system; Increased sodium – through renin; ACTH