Which hormone produced by the kidney helps regulate blood pressure?

Which hormone produced by the kidney helps regulate blood pressure?

• A. Erythropoietin
• B. Calcitonin
• C. Renin
• D. Vitamin D

Answer: (C)

The kidney helps regulate blood pressure by releasing renin, which starts the renin-angiotensin-aldosterone system. When blood pressure falls (or sodium delivery to the distal tubule drops), juxtaglomerular cells in the kidney secrete renin into the bloodstream. Renin converts angiotensinogen (from the liver) into angiotensin I, which is then converted to angiotensin II by ACE. Angiotensin II is a powerful vasoconstrictor and also stimulates aldosterone release from the adrenal cortex. Aldosterone promotes sodium and water reabsorption in the kidneys, increasing blood volume and raising blood pressure. So renin is the kidney-produced factor that initiates this hormonal cascade to regulate blood pressure. Erythropoietin affects red blood cell production, not blood pressure regulation. Calcitonin is produced by the thyroid and mainly influences calcium balance. Vitamin D supports calcium metabolism but is not a primary regulator of blood pressure in this hormonal pathway.

The kidney helps regulate blood pressure by releasing renin, which starts the renin-angiotensin-aldosterone system. When blood pressure falls (or sodium delivery to the distal tubule drops), juxtaglomerular cells in the kidney secrete renin into the bloodstream. Renin converts angiotensinogen (from the liver) into angiotensin I, which is then converted to angiotensin II by ACE. Angiotensin II is a powerful vasoconstrictor and also stimulates aldosterone release from the adrenal cortex. Aldosterone promotes sodium and water reabsorption in the kidneys, increasing blood volume and raising blood pressure. So renin is the kidney-produced factor that initiates this hormonal cascade to regulate blood pressure.

Erythropoietin affects red blood cell production, not blood pressure regulation. Calcitonin is produced by the thyroid and mainly influences calcium balance. Vitamin D supports calcium metabolism but is not a primary regulator of blood pressure in this hormonal pathway.