Question

Which of the following statements best describes the relationship between the hormones ANF and Angiotensin 2 in terms of their physiological effects on the body?

• A. ANF promotes sodium reabsorption, while Angiotensin 2 dilates blood vessels.
• B. ANF dilates blood vessels, while Angiotensin 2 promotes sodium reabsorption.
• C. Both ANF and Angiotensin 2 promote sodium reabsorption.
• D. Both ANF and Angiotensin 2 dilate blood vessels.

Hint:

ANF and Angiotensin 2 perform opposing roles: ANF lowers blood pressure and promotes sodium excretion. Angiotensin 2 raises blood pressure and promotes sodium retention. Understanding these roles helps clarify their effects in the regulation of blood pressure and fluid balance.

Answer 1

The Correct Option is B

Step 1: ANF (Atrial Natriuretic Factor) Function
ANF is released by the heart's atrial cells when blood pressure or volume increases. Its actions include:

Vasodilation, reducing blood pressure.
Increased sodium excretion by the kidneys.
Water excretion, decreasing blood volume.


Step 2: Angiotensin 2 Function
Angiotensin 2 is central to the Renin-Angiotensin-Aldosterone System (RAAS). Its effects are:

Vasoconstriction, raising blood pressure.
Enhanced sodium reabsorption in the kidneys, leading to water retention and increased blood volume.
Stimulation of aldosterone release, which further promotes sodium and water reabsorption.


Step 3: ANF vs. Angiotensin 2

ANF lowers blood pressure and sodium levels through vasodilation and sodium excretion.
Angiotensin 2 raises blood pressure and sodium levels via vasoconstriction and sodium reabsorption.

Consequently, ANF and Angiotensin 2 exert opposing physiological effects.

{ANF dilates blood vessels, whereas Angiotensin 2 facilitates sodium reabsorption.}