Posted inMedicine
Renin–Angiotensin–Aldosterone System (RAAS)
The JG cells detect crisis through three eyes:
Baroreceptor eye → senses renal arterial pressure.
Chemoreceptor eye (Macula densa) → monitors sodium chloride in distal tubule.
Nerve eye → listens to sympathetic nerves releasing norepinephrine.
When all scream “low!”, they release Renin.
Note that Renin is not a hormone — it’s an enzyme. It cleaves angiotensinogen into action.