Final answer:
Renin, produced in the kidney nephrons, regulates blood pressure by initiating the renin-angiotensin-aldosterone system, which leads to vasoconstriction and water retention, stabilizing blood volume and pressure.
Step-by-step explanation:
Renin, produced in the kidney nephrons, regulates blood pressure by initiating the renin-angiotensin-aldosterone system, which leads to vasoconstriction and water retention, stabilizing blood volume and pressure. Renin is produced in the kidney nephrons and has the critical function of regulating blood pressure. It is secreted by the granular cells of the afferent and efferent arterioles, part of the juxtaglomerular complex. Renin initiates the renin-angiotensin-aldosterone system by converting angiotensinogen into angiotensin I, which is further converted into angiotensin II by the angiotensin-converting enzyme (ACE).
Angiotensin II is a potent vasoconstrictor that raises blood pressure and prompts the release of aldosterone, resulting in increased sodium reabsorption, and anti-diuretic hormone (ADH), leading to water retention. These actions collectively stabilize blood volume and pressure.
The correct option is A.