Aldosterone Production System

Aldosterone Production

The hormone aldosterone also plays a role in maintaining blood pressure and fluid and electrolyte balance. Secreted by the adrenal cortex, aldosterone regulates the reabsorption of sodium and water within the nephron.

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Aldosterone Production
Conversely, if blood flow to the kidneys increases, or if the amount of sodium reaching the glomerulus increases, juxtaglomerular cells secrete less renin. A drop-off in renin secretion reduces vasoconstriction and helps to normalize blood pressure.

Triggering active transport

When blood volume drops, aldosterone initiates the active transport of sodium from the distal tubules and the collecting ducts into the bloodstream. That active transport forces sodium back into the bloodstream. When sodium is forced into the bloodstream, more water is reabsorbed and blood volume expands.

Atrial natriuretic peptide

The renin-angiotensin system isn’t the only factor at work balancing fluids in the body. A cardiac hormone called atrial natriuretic peptide (ANP) also helps keep that balance. Stored in the cells of the atria, ANP is released when atrial pressure increases. The hormone opposes the renin-angiotensin system by decreasing blood pressure and reducing intravascular blood volume.

This powerful hormone:

  • suppresses serum renin levels
  • decreases aldosterone release from the adrenal glands
  • increases glomerular filtration, which increases urine excretion of sodium and water
  • decreases ADH release from the posterior pituitary gland
  • reduces vascular resistance by causing vasodilation.

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