reniinangiotensiinialdosteronijärjestelmän

The renin-angiotensin-aldosterone system, often abbreviated as RAAS, is a complex hormonal cascade that plays a crucial role in regulating blood pressure and fluid balance in the body. This system is primarily activated when there is a drop in blood volume or blood pressure, or when sodium levels are low.

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

Angiotensin II is a potent vasoconstrictor, meaning it narrows blood vessels, which directly 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, and the excretion of potassium. This retention of sodium and water increases blood volume, which in turn helps to raise blood pressure. The RAAS also influences thirst, encouraging increased fluid intake.

Dysregulation of the RAAS can contribute to various cardiovascular diseases, including hypertension, heart failure, and kidney disease. Consequently, medications that target components of the RAAS, such as ACE inhibitors and angiotensin II receptor blockers (ARBs), are widely used in the management of these conditions.