RAAS stands for which of the following?

• A. Renin-Angiotensin-Aldosterone System
• B. Renin-Aldosterone-Antidiuretic System
• C. Renal Autoregulatory Angiotensin System
• D. Rapid Angioedema Activation Sequence

Answer: (A)

RAAS is a hormonal cascade that helps regulate blood pressure and fluid balance. It starts when the kidneys release renin in response to low blood pressure, reduced sodium delivery to the distal tubule, or sympathetic stimulation. Renin converts angiotensinogen (made by the liver) into angiotensin I, which is then converted to angiotensin II by ACE. Angiotensin II causes vasoconstriction and stimulates aldosterone release from the adrenal cortex. Aldosterone promotes sodium and water reabsorption in the distal nephron, increasing blood volume and pressure. It can also promote ADH release and thirst, further aiding volume restoration. So the standard name Renin-Angiotensin-Aldosterone System reflects the three key players in this pathway. The other options mix up components or describe nonexistent systems (for example, an antidiuretic system and a rapid activation sequence), which is why they aren’t correct.