A fall in glomerular filtration rate (GFR) activates
A fall in glomerular filtration rate (GFR) activates
juxta glomerular cells to release renin
adrenal cortex to release aldosterone
adrenal medulla to release adrenaline
posterior pituitary to release vasopressin
Solution
Juxtaglomerular apparatus consists of macula densa and juxtaglomerular cells. The apparatus becomes active when there is decrease in renal blood pressure or decrease in glomerular filtration rate. There is increased absorption of $\mathrm{NaCl}$ in ascending limb or loop of Henle. The decreased $\mathrm{NaCl}$ content of filtrate activates cells of macula densa to increase secretion of renin from juxta glomerular cells. Renin convert angiotensinogen to angiotensin peptides.