Question

Which hormone dilates blood vessels to reduce blood pressure, acting opposite to Angiotensin II?

• A. Aldosterone
• B. Renin
• C. Atrial Natriuretic Factor (ANF)
• D. Vasopressin

Hint:

Hormones regulating blood pressure: Angiotensin II → Vasoconstriction → Increases BP Atrial Natriuretic Factor (ANF) → Vasodilation → Decreases BP

Answer 1

The Correct Option is C

Step 1: Understanding the Question:
We are looking for a hormone that functions as a vasodilator and acts as a check-and-balance mechanism against the Renin-Angiotensin system.
Step 3: Detailed Explanation:
1. Angiotensin II is a powerful vasoconstrictor that increases blood pressure and stimulates the release of Aldosterone.
2. When blood flow or pressure in the atria of the heart increases, the atrial walls secrete Atrial Natriuretic Factor (ANF).
3. ANF causes vasodilation (dilation of blood vessels) and promotes the excretion of Sodium and water in urine.
4. These actions effectively decrease the blood volume and lower the blood pressure.
5. Thus, ANF provides an antagonistic effect to the RAAS (Renin-Angiotensin-Aldosterone System).
Step 4: Final Answer:
The hormone is Atrial Natriuretic Factor (C).