RAASjärjestelmä

The RAAS (Renin-Angiotensin-Aldosterone System) is a complex hormonal system that plays a crucial role in regulating blood pressure, fluid balance, and electrolyte levels in the body. It is primarily found in the kidneys and the adrenal glands. The system is activated when blood pressure drops or when the body detects low sodium levels.

The process begins in the kidneys with the release of an enzyme called renin. Renin then acts on a protein in the blood plasma called angiotensinogen, converting it into angiotensin I. Angiotensin I is further converted into angiotensin II by an enzyme called angiotensin-converting enzyme (ACE), which is found mainly in the lungs.

Angiotensin II is a potent vasoconstrictor, meaning it narrows blood vessels, which in turn increases blood pressure. It also stimulates the adrenal glands to release aldosterone. Aldosterone is a hormone that acts on the kidneys, promoting the reabsorption of sodium and water, which further contributes to increased blood volume and blood pressure. Additionally, angiotensin II can stimulate thirst and the release of antidiuretic hormone (ADH), both of which help to conserve water.

The RAAS is a vital mechanism for maintaining homeostasis, but its overactivation can contribute to various cardiovascular diseases, including hypertension, heart failure, and kidney disease. Consequently, medications that target different parts of the RAAS, such as ACE inhibitors and angiotensin receptor blockers (ARBs), are widely used in the treatment of these conditions.