Question

The source of renin in the human kidney is

• A. Macula densa
• B. Juxta-glomerular cells
• C. Interstitial cells
• D. Cells of ducts of Bellini

Answer 1

Answer: (B)

JGA (Juxta-glomerular Apparatus): JGA works via Renin-Angiotensin mechanism which works in the following manner:
A. Fall in glomerular blood flow/glomerular blood pressure/GFR → Activation of the JG cells → Release of Renin in blood.
B. Angiotensinogen → Angiotensin I → Angiotensin II.
C. Angiotensin II performs 2 functions:
(i) Angiotensin II is a powerful vasoconstrictor → Vasoconstriction → Glomerular blood pressure increases → GFR increases.
(ii) Angiotensin II activates the adrenal cortex → Release of Aldosterone → Reabsorption of $N{a}^{+}$ and water from the distal parts of the tubule → Increase in blood pressure → GFR increases.