Which enzyme plays a key role in regulating sodium and water retention and blood pressure?

Which enzyme plays a key role in regulating sodium and water retention and blood pressure?

• A. Renin
• B. Aldosterone
• C. Antidiuretic hormone
• D. BUN

Answer: (A)

Renin is the enzyme that initiates the system that controls sodium and water balance and blood pressure. It is released by the kidneys in response to low blood flow or low salt delivery, and it cleaves angiotensinogen (from the liver) to form angiotensin I. Angiotensin I is then converted to angiotensin II, which causes vasoconstriction and stimulates aldosterone release. Aldosterone, a hormone, increases sodium (and thus water) reabsorption in the distal nephron, raising blood volume and pressure. The other options are hormones or a waste product, not enzymes, so they don’t fit the requirement of being an enzyme that regulates this balance.

Renin is the enzyme that initiates the system that controls sodium and water balance and blood pressure. It is released by the kidneys in response to low blood flow or low salt delivery, and it cleaves angiotensinogen (from the liver) to form angiotensin I. Angiotensin I is then converted to angiotensin II, which causes vasoconstriction and stimulates aldosterone release. Aldosterone, a hormone, increases sodium (and thus water) reabsorption in the distal nephron, raising blood volume and pressure. The other options are hormones or a waste product, not enzymes, so they don’t fit the requirement of being an enzyme that regulates this balance.