The renin-angiotensin-aldosterone system (RAAS) is essential for long-term blood pressure regulation. It involves a complex system of hormones, proteins and enzymes.
The renin-angiotensin-aldosterone system (RAAS) is the system of hormones, proteins, enzymes and reactions that regulate your blood pressure and blood volume on a long-term basis.
It regulates your blood pressure by increasing sodium (salt) reabsorption, water reabsorption (retention) and vascular tone (the degree to which your blood vessels constrict, or narrow). The RAAS consists of three major substances, including:
Enzymes are proteins that help trigger chemical reactions in your body. They build some substances and break others down.
Hormones are chemicals that coordinate different functions in your body by carrying messages through your blood to your organs, muscles and other tissues. These signals tell your body what to do and when to do it.
Your blood pressure is a measurement of the pressure or force inside your arteries with each heartbeat. Normal pressure is important for the proper flow of blood from your heart to your body’s organs and tissues.
Blood pressure depends on many things, including how much blood your heart is pumping and the diameter (the width) of the arteries your blood is moving through.
Many factors can affect your blood pressure, such as certain medications, high cholesterol and smoking. The renin-angiotensin-aldosterone system (RAAS) is responsible for the basic regulation of blood pressure. If you have high blood pressure (hypertension) or low blood pressure (hypotension), it doesn’t necessarily mean there’s an issue with your body’s RAAS.
Both the RAAS and the baroreceptor reflex, or baroreflex, play important roles in regulating blood pressure.
The renin–angiotensin–aldosterone system (RAAS) is a critical regulator of blood volume and systemic vascular resistance on a long-term basis. The baroreceptor reflex, on the other hand, responds in a short-term manner to decreased blood pressure. Arterial baroreceptors inform your autonomic nervous system of minor or rapid beat-to-beat changes in blood pressure.
Several organs, glands and tissues are involved in the RAAS, including your:
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The renin-angiotensin-aldosterone system (RAAS) involves several steps, including:
The renin-angiotensin-aldosterone system (RAAS) is a central feature in the process of heart failure. Initially, adaptations in the RAAS occur in response to the heart’s inability to meet the blood flow demands of vital organ systems.
In particular, the RAAS releases more of the hormone angiotensin II to try to compensate for the lack of blood flow. This excess of angiotensin II subsequently makes heart failure worse. Scientists believe excess angiotensin II contributes to growth in the size of your heart.
Because of this, healthcare providers use different medications that directly affect the RAAS to treat heart failure. These medications include:
A note from Cleveland Clinic
The renin-angiotensin-aldosterone system (RAAS) is crucial for blood pressure regulation. While several factors outside of the RAAS can affect your blood pressure levels, the RAAS can sometimes be responsible. If you’re experiencing symptoms of high or low blood pressure or you’re having a difficult time managing your blood pressure, talk to your healthcare provider. They’re available to help.
Last reviewed by a Cleveland Clinic medical professional on 09/13/2022.
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