Answer:
Angiotensin II is a main effector of RAS and is produced due to the release of the renin that forms in the kidney, angiotensin in turn stimulates the release of aldosterone from the adrenal cortex.
Angiotensin II serves various roles other than vasoconstriction to maintain blood pressure that are:
1. Autoregulation of GFR
2. Reduction of salt excretion through direct and indirect actions on renal tubular cells,
3. Growth modulation of renal cells - these express AT1 receptors.