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Chapter 8. Endocrine Physiology

Analogues of guanosine triphosphate (GTP) such as GTP-γ-S can be used to activate G proteins in isolated cells. Which of the following signaling molecules would NOT be produced in response to GTP-γ-S?

A Arachidonic acid

B Cyclic adenosine monophosphate (cAMP)

C Diacylglycerol (DAG)

D Inositol 1,4,5-triphosphate (IP3)

E Tyrosine kinase

E. Tyrosine kinases do not couple to G proteins; all other choices are second messengers that are produced through activation of G-protein–coupled receptors.

A 28-year-old woman suffered severe trauma to the head in a horseback riding accident that resulted in the complete transection of the pituitary stalk. The plasma levels of which hormone would be expected to increase as a result of this accident?

A Adrenocorticotropic hormone

B Follicle-stimulating hormone

C Growth hormone

D Luteinizing hormone

E Oxytocin

F Prolactin

G Thyroid-stimulating hormone

H Vasopressin

F. Prolactin is the only hormone under primarily negative control from the hypothalamus, via dopamine release. Sectioning of the pituitary stalk therefore increases prolactin secretion, due to loss of dopamine action on lactotrope cells of the anterior pituitary.

A 4-year-old boy was diagnosed with visual disturbances due to a pituitary tumor secreting excess growth hormone. Which of the following conditions would this boy most likely develop without treatment?

A Acromegaly due directly to excess growth hormone

B Acromegaly due to excess insulin-like growth factor (IGF)-1 production

C Dwarfism due directly to excess growth hormone

D Dwarfism due to excess IGF-1 production

E Gigantism due directly to excess growth hormone

F Gigantism due to excess IGF-1 production

F. Excess growth hormone produces gigantism in prepubertal children because the epiphyseal growth plates in long bones have not closed. The effects of growth hormone on linear growth are mediated via IGF-1.

A 58-year-old woman complained of lethargy and weight gain over the past year. Further investigation revealed a painless goiter, thick coarse skin, peripheral edema, and low iodine levels. Which of ...

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