Practice Test 9

A pharmacology experiment gives subjects a drug that blocks aldosterone receptors in the distal nephron. Over several days, subjects show increased urinary sodium excretion and a mild decrease in blood pressure. Which outcome is most consistent with the given physiological response?

A lab monitors acid
base status in subjects after 5 minutes of voluntary hyperventilation. Arterial $P_{CO_2}$ decreases and blood pH increases. Over the next hour, ventilation returns to baseline, and urine pH becomes more alkaline than baseline. Based on the scenario, which interaction is critical for maintaining homeostasis?

(Assume normal kidney function.)