Summary
A hormone cascade that raises blood pressure by vasoconstriction and sodium retention.
In depth
Low pressure makes the kidney release renin, which converts angiotensinogen to angiotensin I, then ACE makes angiotensin II, a vasoconstrictor that stimulates aldosterone release, increasing sodium and water retention. ACE inhibitors treat hypertension.
The system responds to low blood volume. Angiotensin II also stimulates thirst and ADH release. ACE inhibitors and ARBs lower blood pressure.
Example: aldosterone makes kidneys retain sodium and water.
Renin is released from juxtaglomerular cells in response to low pressure, low sodium at the macula densa or sympathetic activation. Angiotensin II is a potent vasoconstrictor, stimulates aldosterone from the adrenal cortex (increasing sodium and water retention and potassium excretion), triggers ADH and thirst, and constricts efferent arterioles. Together these raise blood pressure and volume.
The system is a major drug target: ACE inhibitors (-pril), angiotensin receptor blockers (-sartan), aldosterone antagonists (spironolactone) and direct renin inhibitors treat hypertension, heart failure and kidney disease. A dry cough with ACE inhibitors results from bradykinin accumulation. Overactivity underlies some hypertension. Atrial natriuretic peptide acts oppositely.
Example: after bleeding, RAAS activation helps restore blood pressure.
Frequently asked questions
What is Renin-Angiotensin-Aldosterone System?
A hormone cascade that raises blood pressure by vasoconstriction and sodium retention.
Which area of biology covers Renin-Angiotensin-Aldosterone System, and how advanced is it?
Renin-Angiotensin-Aldosterone System is one of the 51 topics in Human Physiology. It is rated Advanced, so it suits learners who want specialist depth. Related topics in this area include Renal Autoregulation, Osmoregulation and ADH, Blood Pressure.
Can you give an example of Renin-Angiotensin-Aldosterone System?
ACE inhibitors end in -pril.
What should I learn before Renin-Angiotensin-Aldosterone System?
Work through the Beginner topics in Human Physiology first, such as Homeostasis, Tissues and Organs, Skeletal System, then return to Renin-Angiotensin-Aldosterone System. Advanced topics assume the Intermediate vocabulary.
What topics are related to Renin-Angiotensin-Aldosterone System?
The closest topics to Renin-Angiotensin-Aldosterone System are Renal Autoregulation, Osmoregulation and ADH, Blood Pressure, Excretory System. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Renin-Angiotensin-Aldosterone System?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Renin-Angiotensin-Aldosterone System. To practise the whole of Human Physiology, use the Human Physiology quiz.
How is Renin-Angiotensin-Aldosterone System different from Renal Autoregulation?
Renin-Angiotensin-Aldosterone System: A hormone cascade that raises blood pressure by vasoconstriction and sodium retention. Renal Autoregulation: Kidneys adjust arteriole resistance to keep glomerular filtration steady despite blood pressure changes. Read both side by side and note what each one explains.
How should I study Renin-Angiotensin-Aldosterone System step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Renal Autoregulation and explain the difference aloud. Finally, take the Human Physiology quiz and come back to this page for any question you miss.