1,25-dihydroxyvitamin D stimulates the synthesis of the TrpV proteins in the small intestine. The TrpV proteins act as:
A. voltage-sensitive Ca++ channels
B. calcium-sensing receptors
C. serum Ca++ transport proteins
D. intracellular Ca++-binding proteins
E. apical membrane Ca++ channels
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Question 2) A 17-year-old young woman has not had her first menstrual period (menarche) and has no signs of puberty-associated growth spurt, breast development, or pubic hair growth.
Her pediatrician suspects hypogonadism/delayed puberty of some form.
If this patient had a form of primary hypogonadism, one would expect to see:
A. increased estrogen levels
B. increased FSH levels
C. increased androgens levels
D. increased TSH levels
E. increased GH levels
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Question 3) The parathyroid glands respond rapidly to hypocalcemia. The protein responsible for the rapid response of the principal cells to a falling calcium level is:
A. the PTH receptor
B. membrane Ca++-ATPase
C. Ca++-sensing receptor
D. the Na+-Ca++ exchange antiporter
E. TRPV5 Ca2+ channel
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Question 4) Osteoporosis can result from excessive production of RANKL by osteoblasts. A molecule that directly inhibits RANKL and protects bones from osteoclast overactivity is:
A. PTH
B. osteoprotegerin
C. alkaline phosphatase
D. osteoid
E. RANK
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Question 5) PTH is secreted in a regulated manner. Which of the following directly increases PTH synthesis and/or secretion?
A. elevated 1,25-dihydroxyvitamin D
B. decreased blood phosphate levels (hypophosphatemia)
C. decreased blood Ca++ levels (hypocalcemia)
D. elevated blood K+ levels (hyperkalemia)
E. elevated Mg++ levels (hypermagnesemia)
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Question 6) The vitamin D receptor belongs to which class of receptors:
A. G proteincoupled receptor
B. tyrosine kinase receptor
C. nuclear hormone receptor
D. calcium-sensing receptor
E. JAK/STAT receptor
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Question 7) Lack of vitamin D can cause rickets in children. Of the following, which is the most important lifestyle activity that promotes normal endogenous vitamin D production?
A. playing outside
B. exercising at a gym
C. eating green vegetables
D. consuming highly unsaturated oils (e.g., olive oil)
E. drinking fruit juices
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Question 8) Glucagon has an important counter-regulatory role that prevents hypoglycemia. Which glucagon-stimulated enzyme increases hepatic glucose production and, thus, blood glucose?
A. hormone-sensitive lipase
B. lipoprotein lipase
C. fructose-1,6-bisphosphatase
D. glycogen synthase
E. fatty acyl oxidase
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Question 9) Endogenous vitamin D synthesis begins in the:
A. intestine
B. kidney
C. liver
D. skin
E. bone
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Question 10) A 65-year-old woman presents with acute, severe flank pain radiating toward the pelvis.
She also complains of some chronic musculoskeletal pain and indigestion. Radiology reveals a kidney stone in her ureter. Blood chemistry reveals hypercalcemia, and urine chemistry reveals hypercalciuria and hyperphosphaturia.
An endocrine pathology most consistent with these findings is:
A. infection of the GI tract that inhibits calcium and phosphate absorption
B. an adenoma of the parathyroid glands, secreting excessive PTH
C. hepatocellular carcinoma of the liver, resulting in overproduction of 25-hydroxyvitamin D
D. a medullary carcinoma of the thyroid, secreting large amounts of calcitonin
E. autoimmune destruction of the parathyroid glands
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