Bloodstream, lung endothelium and adrenal cortex

Renin-angiotensin-aldosterone system mnemonics

Low blood pressure in, sodium and water back.

The order

RAAS spells its own order: Renin → Angiotensin I → (ACE) → Angiotensin II → Aldosterone

What aldosterone does

Aldosterone saves salt — and where sodium goes, water flows

A mnemonic only sticks once you have used it. The quiz and the rebuild below both draw on these exact steps.