Angiotensin II (Ang II) is a pivotal hormone in the renin-angiotensin-aldosterone system (RAAS) that regulates blood pressure, fluid balance, and electrolyte homeostasis. It exerts multiple effects across various organs, contributing extensively to cardiovascular and renal physiology.

Key Functions of Angiotensin II

1. Facilitates the Release of Norepinephrine from Post-ganglionic Sympathetic Neurons

   • Ang II enhances norepinephrine release and inhibits its re-uptake at sympathetic nerve terminals, potentiating sympathetic nervous system activity.cvphysiology

2. Increases the Sensitivity of Baroreflex by Acting on Brain

   • Ang II actually decreases baroreflex sensitivity, which allows higher sympathetic tone and maintains elevated blood pressure during stress. Hence, the claim that it increases baroreflex sensitivity is incorrect.wikipedia

3. Produces Arteriolar Contraction

   • Ang II is a potent vasoconstrictor acting mainly on arterioles via AT1 receptors, increasing systemic vascular resistance and blood pressure.cvphysiology+1

4. Increases the Secretion of Vasopressin

   • Ang II stimulates the release of vasopressin (antidiuretic hormone) from the posterior pituitary, enhancing water reabsorption to increase blood volume.wikipedia+1

Which One is NOT a Function of Angiotensin II?

Among the options provided, the statement that angiotensin II increases baroreflex sensitivity by acting on the brain is not correct. Instead, angiotensin II decreases baroreflex sensitivity, thereby permitting increased sympathetic nervous system activity necessary to raise and maintain blood pressure during hypotensive states.cvphysiology+1

Summary Table

Conclusion

The correct answer to the question “Which one is NOT a function of angiotensin II?” is:

(2) Increases the sensitivity of baroreflex by acting on brain