when glomerular filtration pressure is reduced , glomerular
filtration rate is reduced .
A fall in glomerular filtration pressure will activate the
JG cells to release renin , which then convert
angiotensinogen in blood to angiotensin I and then angiotensin
converting enzyme converts angiotensin I further to angiotensin II
.
Angiotensin II being a powerful vasoconstrictor increases the
glomerular pressure and there by GFR.
Angiotensin II also activates adrenal cortex to release
aldosterone, which also increases reabsorption of sodium and water
from the distal part of tubules.this also helps in increasing
glomerular filtration pressure and GFR.
THIS MECHANISM IS KNOWN AS RENIN-ANGIOTENSIN
MECHANISM