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Aldosterone is the main mineralocorticoid steroid hormone produced by the zona glomerulosa of the adrenal cortex in the adrenal gland. [ 4 ] [ 5 ] It is essential for sodium conservation in the kidney, salivary glands, sweat glands, and colon. [ 6 ]
The 'single effect' describes the fact that the ascending thick limb of the loop of Henle is not permeable to water but is permeable to sodium chloride. This allows for a countercurrent exchange system whereby the medulla becomes increasingly concentrated, but at the same time setting up an osmotic gradient for water to follow should the ...
The collecting duct system of the kidney consists of a series of tubules and ducts that physically connect nephrons to a minor calyx or directly to the renal pelvis.The collecting duct participates in electrolyte and fluid balance through reabsorption and excretion, processes regulated by the hormones aldosterone and vasopressin (antidiuretic hormone).
In the adrenal cortex, angiotensin II acts to cause the release of aldosterone. Aldosterone acts on the tubules (e.g., the distal convoluted tubules and the cortical collecting ducts) in the kidneys, causing them to reabsorb more sodium and water from the urine. This increases blood volume and, therefore, increases blood pressure.
At this location, in the wall of the last portion of distal straight tubule, there is a modified region of tubular epithelium called the macula densa.(Fig. 5 in Kumaran and Hanukoglu 2020) [5] Cells in the macula densa respond to changes in the sodium chloride levels in the distal tubule of the nephron via the tubuloglomerular feedback (TGF) loop.
The opposite mechanism is called transrepression. The hormone receptor without ligand binding interacts with heat shock proteins and prevents the transcription of targeted genes. Aldosterone and cortisol (a glucosteroid ) have similar affinity for the mineralocorticoid receptor; however, glucocorticoids circulate at roughly 100 times the level ...
Mineralocorticoids (such as aldosterone) produced in the zona glomerulosa help in the regulation of blood pressure and electrolyte balance. The glucocorticoids cortisol and cortisone are synthesized in the zona fasciculata; their functions include the regulation of metabolism and immune system suppression.
The outermost layer, the zona glomerulosa is the main site for the production of aldosterone, a mineralocorticoid. The synthesis and secretion of aldosterone are mainly regulated by the renin–angiotensin–aldosterone system. The zona glomerulosa cells express a specific enzyme aldosterone synthase (also known as CYP11B2).