Tripp, M. 2022
The RAAS System
- The renin-angiotensin-aldosterone system is an endocrine feedback system
What does it do?
- It contributes to blood/fluid volume regulation and systemic vascular resistance.
Basically, it helps to regulate blood pressure and fluid and electrolyte balances in the
body.
What organs are involved? How?
- Kidney
o this is usually how the system is triggered. Think of decreases in blood pressure
and serum sodium levels causing less renal perfusion.
o produces renin, which helps convert angiotensinogen to angiotensin I
o eventually, aldosterone will act on the tubules of each nephron to increase
sodium retention (water follows sodium) to increase fluid volume and potassium
excretion
- Lungs
o This is a major site of ACE production/expression, although also expressed in the
liver, intestine, brain, testis, heart, and kidney
o ACE facilitates the conversion of angiotensin I to angiotensin II
- Adrenal glands
o The cortex (think cortex crust, medulla middle) regulates the production of
aldosterone
- Liver
o Continuously produces angiotensinogen, which is later cleaved/activated to
angiotensin I
Tripp, M. 2022
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Vasculature (blood vessels)
o Angiotensin II acts on blood vessels to cause vasoconstriction, thereby increasing
blood pressure
- Pituitary Gland
o Angiotensin II acts on the posterior pituitary gland to stimulate the release of
antidiuretic hormone (ADH), which then acts on the kidneys to reabsorb water
and increase blood volume
What hormones are involved?
- Renin
- Angiotensinogen, angiotensin I, & angiotensin II
- Aldosterone
- Antidiuretic hormone
Below is some useful info from Khan Academy: