Question

Choose the correct sequence of enzyme activation in human kidney when there is a fall in GFR

• A. Renin - Angiotensin II - Aldosterone
• B. Angiotensin II - Aldosterone - Renin
• C. Renin - Aldosterone - Angiotensin II
• D. Aldosterone - Renin - Angiotensin II

Answer 1

The correct option is A Renin - Angiotensin II - Aldosterone

When the blood volume and blood pressure decrease, juxtaglomerular cells in the kidneys secrete the enzyme renin. Renin catalyzes the conversion of angiotensinogen to angiotensin II. Angiotensin II, being a powerful vasoconstrictor, increases the glomerular blood pressure and thereby GFR. Angiotensin II also activates the adrenal cortex to release Aldosterone.

Aldosterone promotes the absorption of Nacl and water from DCT. This also leads to an increase in blood pressure and GFR. Thus Renin-Angiotensin II- Aldosterone (RAAS) help in maintaining GFR.