Optometry Admission Test (OAT) 2025 – 400 Free Practice Questions to Pass the Exam

Aldosterone plays a pivotal role in regulating blood volume primarily through its actions on the kidneys. As a steroid hormone produced by the adrenal cortex, aldosterone promotes sodium reabsorption in the renal tubules. When sodium is reabsorbed, water follows due to osmosis, which leads to an increase in blood volume.

By increasing sodium retention, aldosterone effectively elevates blood volume and, consequently, blood pressure, making it an essential hormone in the body's fluid balance and blood pressure regulation. Its primary function is to maintain or elevate blood pressure during states of hypotension or dehydration.

This physiological mechanism is crucial for maintaining homeostasis, especially in scenarios where fluid loss occurs, such as sweating, blood loss, or dehydration. Thus, the correct answer highlights the direct relationship between aldosterone and increased blood volume, reinforcing the importance of this hormone in fluid retention and overall circulatory health.