Practice Test 4

A patient with primary adrenal insufficiency has low cortisol at baseline. After an acute stressor, plasma ACTH is markedly elevated, but cortisol remains low and blood pressure decreases. What change is most consistent with the described homeostatic process?

A patient with central diabetes insipidus has low circulating ADH. After 12 hours without water, plasma osmolality rises from 290 to 310 mOsm/kg, but urine remains dilute and high-volume. Which of the following best describes the feedback mechanism illustrated?