What effect does aldosterone have on blood pressure?

Aldosterone is a hormone produced by the adrenal glands, and its primary role is to regulate sodium and potassium levels in the body. When aldosterone is released, it prompts the kidneys to reabsorb more sodium from the urine back into the bloodstream. This process leads to an increase in the amount of sodium in the blood, which then causes water to follow the sodium due to osmosis. As a result, there is an increase in blood volume. An elevated blood volume typically results in higher blood pressure, as the heart must pump harder to move the increased volume of blood through the vascular system.

In contrast, other choices do not accurately represent the role of aldosterone. Aldosterone does not decrease blood volume; rather, it promotes fluid retention. It also encourages sodium reabsorption rather than excretion. Furthermore, while aldosterone affects potassium levels, its function primarily involves the retention of sodium rather than a direct decrease in potassium retention. Therefore, the correct answer emphasizes that aldosterone's action directly correlates to an increase in blood volume, ultimately influencing blood pressure.