Renin-angiotensin system

From WikiMD's Wellness Encyclopedia

Renin-angiotensin system (RAS) is a hormone system that regulates blood pressure and fluid balance. When renal blood flow is compromised, the system is activated to increase blood pressure and restore adequate blood flow. If this system is overactive, it can lead to hypertension.

Overview[edit | edit source]

The RAS is essential for regulation of blood pressure and fluid balance in the body. It is primarily composed of the enzymes renin and angiotensin, and the receptors that these enzymes act upon.

Function[edit | edit source]

The RAS is activated when there is a decrease in blood flow to the kidney. This can occur due to low blood volume, low blood pressure, or low sodium concentration. The decreased blood flow causes the release of renin from the juxtaglomerular cells in the kidney. Renin then acts on angiotensinogen, which is produced by the liver and released into the bloodstream. This reaction forms angiotensin I, which is then converted into angiotensin II by the enzyme angiotensin-converting enzyme (ACE). Angiotensin II is a potent vasoconstrictor, which means it narrows the blood vessels and increases blood pressure. It also stimulates the release of aldosterone from the adrenal cortex, which causes the kidneys to retain sodium and water, further increasing blood volume and blood pressure.

Clinical significance[edit | edit source]

Overactivity of the RAS can lead to hypertension, which is a major risk factor for cardiovascular disease, including stroke, heart attack, and heart failure. Drugs that inhibit the RAS, such as ACE inhibitors and angiotensin II receptor blockers, are commonly used to treat hypertension.

See also[edit | edit source]

Renin-angiotensin system Resources
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Contributors: Prab R. Tumpati, MD