Atrial Natriuretic Peptide (ANP) is a hormone produced by the heart's atria, specifically 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 works in opposition to other hormones like aldosterone and angiotensin II, which typically increase blood pressure. By counteracting these hormones, ANP plays a crucial role in maintaining cardiovascular health and preventing conditions such as hypertension and heart failure.