Final answer:
Aldosterone is produced in the adrenal cortex, and angiotensin II triggers its release. It acts on the distal convoluted tubule to reabsorb sodium (Na+), causing an increase in water reabsorption and a subsequent rise in blood pressure.
Step-by-step explanation:
Aldosterone is a hormone produced in the adrenal cortex. It plays a crucial role in regulating electrolyte balance by acting on the kidneys. Specifically, angiotensin II controls the release of aldosterone from the adrenal glands. This hormone's primary action is in the distal convoluted tubule of the kidney, where it stimulates the reabsorption of sodium (Na+). Following the increase in sodium reabsorption, water is also reabsorbed, leading to an increase in blood volume and, consequently, blood pressure. This effect is part of the renin-angiotensin-aldosterone system (RAAS), which activates in response to low blood pressure to help regulate blood pressure homeostasis.
In the distal convoluted tubule and collecting ducts, aldosterone encourages the sodium-potassium pump, leading to increased sodium reabsorption into the bloodstream and the excretion of potassium into the renal filtrate. The increased osmolality in the extracellular fluid, following sodium reabsorption, creates the gradient for water to follow osmotically, helping to correct the initial stimulus for aldosterone release.