Chapter 18. The Pituitary Gland
A neuroscientist is studying communication between the hypothalamus and pituitary in a rat model. She interrupts blood flow through the median eminence and then measures circulating levels of pituitary hormones following appropriate physiologic stimulation. Secretion of which of the following hormones will be unaffected by the experimental manipulation?
Loss of which of the following pituitary hormones might be expected to increase responses to painful stimuli?
A. α-Melanocyte–stimulating hormone (α-MSH)
A 20-year-old African American woman is evaluated for evaluation of patches of skin on her face and hands that have lost pigmentation over a period of weeks. She is otherwise healthy. Blood tests reveal the presence of autoantibodies to melanocytes. The most likely diagnosis is
C. primary adrenal insufficiency.
A scientist finds that infusion of growth hormone into the median eminence of the hypothalamus in experimental animals inhibits the secretion of growth hormone and concludes that this proves that growth hormone feeds back to inhibit GHRH secretion. Do you accept this conclusion?
A. No, because growth hormone does not cross the blood-brain barrier.
B. No, because the infused growth hormone could be stimulating dopamine secretion.
C. No, because substances placed in the median eminence could be transported to the anterior pituitary.
D. Yes, because systemically administered growth hormone inhibits growth hormone secretion.
E. Yes, because growth hormone binds GHRH, inactivating it.
The growth hormone receptor
B. requires dimerization to exert its effects.
C. must be internalized to exert its effects.
D. resembles the IGF-I receptor.
E. resembles the ACTH ...