Optometry Admission Test (OAT) Practice

What is the function of atrial natriuretic peptide?

1. Stimulates T cell maturation

2. Involved in osmoregulation and vasodilation

3. Maintains reproductive health

4. Regulates metabolic rate

The correct answer is: Involved in osmoregulation and vasodilation

Atrial natriuretic peptide (ANP) is a hormone produced by the heart's atrial cells in response to atrial stretching or high blood volume. Its primary function is to regulate blood pressure and fluid balance in the body. ANP induces vasodilation, which helps to lower blood pressure, and promotes natriuresis, the excretion of sodium through the urine. This process ultimately leads to a reduction in blood volume and blood pressure. In the context of the options provided, the involvement of ANP in osmoregulation is significant as it helps control the balance of fluids and electrolytes, particularly sodium, in the body. By promoting the excretion of sodium, it also encourages water to follow, reducing overall fluid volume. Additionally, vasodilation helps to decrease vascular resistance, which further aids in lowering blood pressure. Therefore, option B accurately captures the primary roles of atrial natriuretic peptide, linking it directly to its physiological effects on the cardiovascular and renal systems.