Atrial natriuretic peptide (ANP) is a hormone produced by the heart's atria in response to increased blood volume and pressure. Its primary function is to help regulate blood pressure and fluid balance in the body. ANP promotes the excretion of sodium and water by the kidneys, which leads to a decrease in blood volume and, consequently, lower blood pressure. ANP also inhibits the release of other hormones, such as aldosterone and renin, which are involved in blood pressure regulation. By counteracting these hormones, ANP plays a crucial role in maintaining cardiovascular health and preventing conditions like hypertension and heart failure.