What is the effect of atrial natriuretic peptide (ANP) on blood volume?

Atrial natriuretic peptide (ANP) plays a crucial role in regulating blood volume and blood pressure. This peptide is released by the atria of the heart when there is an increase in blood volume, which often occurs during fluid overload. Its primary function is to counteract the effects of other hormones that lead to sodium retention and consequently, water retention.

When ANP is released, it promotes natriuresis, which is the excretion of sodium in the urine. As sodium is eliminated, water follows osmotically, leading to a decrease in blood volume. This decrease in blood volume helps to lower blood pressure and maintain fluid balance in the body. By promoting sodium and water excretion, ANP serves as a critical regulatory mechanism to help prevent conditions related to excessive blood volume, such as hypertension.

This physiological action aligns with the correct choice regarding the effect of ANP on blood volume, affirming that it promotes sodium excretion, thereby decreasing blood volume.