Final answer:
Atrial natriuretic peptide (ANP) promotes c) water and Na+ excretion in the urine, which helps reduce blood volume and pressure. It inhibits the actions of aldosterone and ADH, leading to increased urinary excretion of these substances.
Step-by-step explanation:
The hormone atrial natriuretic peptide (ANP), produced by atrial cells in the heart, promotes the excretion of both c) water and Na+ in the urine.
ANP acts as an antagonist to aldosterone and angiotensin II by promoting the loss of sodium and water from the kidneys, and inhibiting the release of aldosterone and antidiuretic hormone (ADH), leading to a reduction in blood volume and blood pressure.
This peptide hormone is released in response to high blood volume, which stretches the atrial walls, triggering the release of ANP to help reduce the blood volume and pressure by increasing the excretion of Na+ and water in the urine.