The thirst mechanism is invoked when
A) the plasma osmolarity increases.
B) the plasma osmolarity decreases.
C) hypothalamic osmoreceptors are activated.
D) both (a) and (b) above.
E) both (a) and (c) above.

Question

Quizplus · Accepted Answer

The thirst mechanism is invoked when both the plasma osmolarity increases (due to high concentration of solutes in the blood) and hypothalamic osmoreceptors are activated, as they detect changes in water concentration. However, decreased plasma osmolarity may lead to reduced release of antidiuretic hormone (ADH), leading to more water excretion and decreased thirst response.

The Thirst Mechanism Is Invoked When