Q15

Osmoregulation is the process by which water and salt (or solute) concentration in the blood achieves homeostasis using aldosterone and anti-diuretic hormones (ADH). Aldosterone acts on sodium ions causing them to be actively reabsorbed back into the blood from the kidney. As a result, the blood in the capillaries surrounding the kidney’s distal tubule will have a higher solute concentration. An increase in solute concentration in the blood causes the pituitary gland to secrete ADH into the blood stream to increase their permeability of distal tubules to water. This increases the amount of water reabsorbed back into the blood from the kidney. The amount of ADH secreted will decrease when the solute concentration in the blood returns to normality establishing osmoregulation.
A dehydrated marathon runner consumed a concentrated salt sports drink to satisfy his thirst.
How does his body control the two hormones, ADH and aldosterone, to help to re- establish normal water balance?
A. ADH is released and aldosterone is inhibited
B. ADH is inhibited and aldosterone is released.
C. Both ADH and aldosterone are released.
D. Both ADH and aldosterone are inhibited.