Aldosterone is described as what?

• A. A hormone that reduces Na+ retention and lowers blood volume.
• B. Salt-retaining hormone that promotes Na+ retention by the kidneys; acts on the DCT; released by the adrenal cortex; responds to decreased blood pressure.
• C. A hormone produced by the kidneys to stimulate urine production.
• D. A molecule that inhibits aldose.

Answer: (B)

Aldosterone is a salt-retaining hormone produced by the adrenal cortex. It increases sodium reabsorption in the kidney, particularly in the distal convoluted tubule, and promotes water retention to raise blood volume and pressure. It is released in response to signals of low blood pressure or low sodium via the renin-angiotensin-aldosterone system. This description fits because it specifies its role in retaining Na+, its site of action in the kidney, its adrenal origin, and its response to decreased blood pressure. The other options misstate its function or origin: one suggests it reduces Na+ retention and lowers blood volume; another says it’s produced by the kidneys to stimulate urine production; and another mentions inhibiting aldose, which is unrelated.