RENIN is protease secreted into blood by juxtaglomerular cells around renal afferent arterioles, is synthesized as pro-renin, its secretion is stimulated by decreased blood pressure and extracellular fluid volume ECF.
In the blood, RENIN converts the glycoprotein from the liver
ANGIOTENSINOGEN
into
ANGIOTENSIN I
which is split by the angiotensin-converting enzyme
into
ANGIOTENSIN II.
ANGIOTENSIN II
constricts arterioles
increases blood pressure
(Goldblatt hypertension)
stimulates adrenocortical secretion of aldosterone.
ANGIOTENSIN II
binds to receptors in zona glomerulosa
of adrenal cortex
to stimulate production/secretion of
ALDOSTERONE.
ALDOSTERONE
its secretion is also stimulated by ACTH.
Low Na+ (?) and high K+ in blood
facilitates Na+ reabsorption from distal/collecting tubules
and secretion of K+ and H+
with consequent increase in blood volume and blood pressure.