Final answer:
Atrial natriuretic peptide (ANP) helps in reducing blood pressure by causing vasodilation, promoting the excretion of sodium and water through urine, and inhibiting the actions of hormones that increase blood volume and pressure.
Step-by-step explanation:
The action of atrial natriuretic peptide (ANP) is to lower blood pressure, primarily by causing vasodilation and by promoting diuresis (the increased production of urine). ANP is produced by the heart's atria in response to high blood volume and high blood pressure, leading to the release of this peptide hormone. Once released, ANP inhibits the reabsorption of sodium in the kidneys, which also reduces the reabsorption of water due to osmotic balance, consequently resulting in increased urine production.
This loss of sodium and water from the body decreases blood volume and pressure. Furthermore, ANP inhibits the secretion of hormones like aldosterone, ADH (antidiuretic hormone), and renin, which normally help in water and sodium retention, thus acting counter to their effects.