reniininangiotensiinijärjestelmän

The renin-angiotensin system, often abbreviated as RAS and known in Finnish as reniinin-angiotensiinijärjestelmä, is a complex hormonal system that plays a crucial role in regulating blood pressure and fluid balance in the body. It is a vital component of the cardiovascular system and is involved in maintaining homeostasis.

The system is initiated when the kidneys detect a drop in blood pressure or reduced blood flow. In response, specialized cells in the kidneys release an enzyme called renin. Renin then enters the bloodstream and acts on a protein produced by the liver called angiotensinogen. This interaction cleaves angiotensinogen, producing a peptide called angiotensin I.

Angiotensin I is then converted into angiotensin II by an enzyme primarily found in the lungs, known as angiotensin-converting enzyme (ACE). Angiotensin II is the main active component of the RAS. It exerts its effects through various mechanisms. It is a potent vasoconstrictor, meaning it narrows blood vessels, which directly increases blood pressure. Additionally, angiotensin II stimulates the adrenal glands to release aldosterone, a hormone that promotes sodium and water reabsorption in the kidneys, further contributing to increased blood volume and pressure. It also influences thirst and the release of antidiuretic hormone (ADH), which also helps to conserve water.

Dysregulation of the renin-angiotensin system can lead to or exacerbate conditions such as hypertension (high blood pressure), heart failure, and kidney disease. Consequently, many medications used to treat these conditions target specific components of the RAS, such as ACE inhibitors and angiotensin II receptor blockers (ARBs).