Ace the Certified Nephrology Nurse 2025 Exam – Dive into Dialysis Mastery!

The renin-angiotensin-aldosterone system (RAAS) plays a crucial role in regulating blood pressure through its multifaceted actions. When blood pressure drops, the kidneys sense this change and release renin, which catalyzes the conversion of angiotensinogen (produced by the liver) into angiotensin I. Angiotensin I is then transformed into angiotensin II by the enzyme ACE (angiotensin-converting enzyme) primarily in the lungs.

Angiotensin II has several physiological effects that contribute to the elevation of blood pressure:

1. **Vasoconstriction**: Angiotensin II is a potent vasoconstrictor, meaning it narrows blood vessels. This constriction increases the resistance the heart must work against, which raises blood pressure.

2. **Fluid Retention**: Angiotensin II stimulates the adrenal glands to release aldosterone, a hormone that prompts the kidneys to retain sodium and water. This increase in blood volume also contributes to elevated blood pressure.

3. **Stimulating Thirst and ADH Release**: Angiotensin II can also enhance thirst and stimulate the release of antidiuretic hormone (ADH), which further aids in water retention by the kidneys