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A fall in glomerular filtration rate (GFR) activates
A
Posterior pituitary to release vasopressin
B
Juxtaglomerular cells to release renin
C
Adrenal cortex to release aldosterone
D
Adrenal medulla to release adrenaline
Detailed Solution
The kidney regulates its own filtration rate through the juxtaglomerular apparatus (JGA).
A fall in GFR (or in glomerular blood flow or pressure) directly activates the juxtaglomerular (JG) cells to release renin.
Renin converts angiotensinogen in the blood into angiotensin I, which is further converted into angiotensin II.
Angiotensin II is a powerful vasoconstrictor that raises glomerular blood pressure and thereby GFR; it also stimulates the adrenal cortex to release aldosterone.
So aldosterone release is a later, indirect step, and vasopressin release is triggered by osmoreceptors responding to changes in body fluid volume and concentration.
Hence a fall in GFR activates the juxtaglomerular cells to release renin.
A fall in GFR (or in glomerular blood flow or pressure) directly activates the juxtaglomerular (JG) cells to release renin.
Renin converts angiotensinogen in the blood into angiotensin I, which is further converted into angiotensin II.
Angiotensin II is a powerful vasoconstrictor that raises glomerular blood pressure and thereby GFR; it also stimulates the adrenal cortex to release aldosterone.
So aldosterone release is a later, indirect step, and vasopressin release is triggered by osmoreceptors responding to changes in body fluid volume and concentration.
Hence a fall in GFR activates the juxtaglomerular cells to release renin.