What is the RAAS and Why is it Important?

Photo by Dr. Haus

Renin-Angiotensin-Aldosterone System (RAAS)

The Renin-Angiotensin-Aldosterone System, also called RAAS, is a hormone system that helps maintain blood pressure and blood volume.  RAAS is one of the most important regulatory systems of the body and I always joke that it is the only information you need to know to be a doctor (it is both a joke and not a joke...).

 

The steps of the RAAS are written out below and followed by an infographic:

1. The kidneys release renin due to decreased blood flow to the kidneys, low sodium detected by the kidneys, and/or decreased blood pressure to the kidneys
   
2. The renin converts angiotensinogen to angiotensin 1 in the bloodstream
   
3. Angiotensin 1 arrives at the lungs where the Angiotensin Converting Enzyme (ACE) converts angiotensin 1 to angiotensin 2
   
4. Angiotensin 2 has two effects: systemic vasoconstriction and the release of aldosterone from the kidneys
   
5. Aldosterone increases sodium reabsorption and potassium secretion in the kidneys
   
6. More water is reabsorbed into the body and less water is urinated out
   
   
   
   
   
   

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Why is RAAS Important?

The RAAS is extremely important for maintaining blood pressure in the body.  If blood pressure gets too low, the organs of the body will not be able to get all the blood flow they need for oxygen and nutrients.

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