Final answer:
The hormone aldosterone is released by the adrenal cortex, influenced by the production of angiotensin II that prompts sodium reabsorption in the kidneys.
Step-by-step explanation:
The structure that releases the hormone aldosterone is the adrenal cortex. Aldosterone plays a pivotal role in regulating sodium reabsorption and potassium excretion in the kidneys, working primarily on the distal convoluted tubules and collecting ducts. The release of aldosterone is stimulated by angiotensin II, which is part of the renin-angiotensin-aldosterone system (RAAS), a critical regulator of blood volume and systemic blood pressure. The process of angiotensin II production begins when decreased blood pressure prompts the release of renin, which then produces angiotensin I. Angiotensin I is converted to angiotensin II by the enzyme angiotensin-converting enzyme (ACE). Angiotensin II subsequently stimulates the adrenal cortex to release aldosterone. This hormone then enhances the reabsorption of sodium ions, which in turn promotes water retention, increasing blood volume and blood pressure.