Outline the renin-angiotensin-aldosterone system's vascular effects.

• A. Ang II dilates vessels and reduces aldosterone
• B. Renin cleaves angiotensinogen to Ang I; ACE converts to Ang II; Ang II vasoconstricts and stimulates aldosterone release; increases BP and promotes vascular remodeling.
• C. Aldosterone directly neutralizes Ang II
• D. Renin inactivates angiotensinogen; decreases BP

Answer: (C)

The vascular effects of the renin-angiotensin-aldosterone system come from a cascade that increases vascular tone and blood pressure. When the kidney detects reduced renal perfusion or sodium delivery, it releases renin. Renin then cleaves angiotensinogen to angiotensin I, and ACE converts angiotensin I into angiotensin II. Ang II is a powerful vasoconstrictor that narrows arterioles, boosting systemic vascular resistance and raising blood pressure. It also stimulates the adrenal cortex to secrete aldosterone, which acts on the kidneys to reabsorb sodium and water, expanding blood volume and further increasing BP. Ang II also promotes vascular remodeling by encouraging smooth muscle growth and fibrotic changes in vessels. Aldosterone does not neutralize Ang II; its primary vascular impact is via volume expansion rather than direct inactivation of Ang II. This is why the statement that aldosterone neutralizes Ang II is not correct, and the sequence starting with renin cleaving angiotensinogen and forming Ang II, which then causes vasoconstriction and aldosterone release, best describes the RAAS vascular effects.