rainiiniangiotensiinijärjestelmä

The Renin-Angiotensin System (RAS), known in Finnish as the rainiini-angiotensiinijärjestelmä, is a crucial hormonal system that regulates blood pressure and fluid balance in the body. It plays a significant role in maintaining cardiovascular homeostasis. The system is activated primarily by a drop in blood pressure or a decrease in sodium levels detected by the kidneys.

When stimulated, the kidneys release an enzyme called renin into the bloodstream. Renin then acts on a liver-produced protein called angiotensinogen, converting it into angiotensin I. Angiotensin I is relatively inactive, but it is further processed by an enzyme called angiotensin-converting enzyme (ACE), which is found mainly in the lungs and blood vessels. This conversion yields 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, a hormone that promotes sodium and water reabsorption in the kidneys, further increasing blood volume and pressure. Additionally, angiotensin II can stimulate thirst and the release of antidiuretic hormone (ADH), which also contributes to water retention.

The RAS can be overactivated in certain conditions, leading to chronic high blood pressure (hypertension) and other cardiovascular problems. Medications that target the RAS, such as ACE inhibitors and angiotensin receptor blockers (ARBs), are widely used to treat hypertension and heart failure by inhibiting the system's effects.