Final answer:
Atrial natriuretic hormone (ANH) causes an increase in the excretion of sodium and water, leading to a decrease in blood volume and blood pressure. The answer is (b) Increase, decreasing.
Step-by-step explanation:
Atrial natriuretic hormone (ANH) promotes a decrease in the excretion of sodium and water; thus decreasing blood volume and blood pressure. ANH is secreted by cells in the atria of the heart in response to high blood volume, causing loss of sodium and water from the kidneys. This promotes a reduction in blood volume and blood pressure.
ANH, also known as atrial natriuretic peptide (ANP), is secreted by cardiac muscle cells in the atria of the heart when they are excessively stretched due to increased blood volume. ANH acts as an antagonist to angiotensin II and functions to reduce blood pressure and blood volume. It does this by promoting the excretion of sodium and water through the kidneys, and by suppressing the production and release of renin, aldosterone, and ADH (anti-diuretic hormone). These hormones normally help to retain sodium and water in the body, so by inhibiting them, ANH causes a net loss of fluid, thereby reducing blood volume and blood pressure.