Chapter 21: Hormonal Control of Calcium & Phosphate Metabolism & the Physiology of Bone

Chapter 21. Hormonal Control of Calcium & Phosphate Metabolism & the Physiology of Bone

A patient with parathyroid deficiency developing 10 days after inadvertent damage to the parathyroid glands during thyroid surgery would probably have

A. low plasma phosphate and Ca²⁺ levels and tetany.

B. low plasma phosphate and Ca²⁺ levels and tetanus.

C. a low plasma Ca²⁺ level, increased muscular excitability, and spasm of the muscles of the upper extremity (Trousseau sign).

D. high plasma phosphate and Ca²⁺ levels and bone demineralization.

E. increased muscular excitability, a high plasma Ca²⁺ level, and bone demineralization.

In an experiment, a rat is infused with a small volume of a calcium chloride solution, or sodium chloride as a control. Compared to the control condition, which of the following would result from the calcium load?

A. Bone demineralization

B. Increased formation of 1,25-dihydroxycholecalciferol

C. Decreased secretion of calcitonin

D. Decreased blood coagulability

E. Increased formation of 24,25-dihydroxycholecalciferol

In the same rat, which of the following would be increased?

A. Intestinal absorption of calcium

B. Expression of TRPV5 in the renal proximal tubule

C. NaPi-IIb abundance in the enterocyte apical membrane

D. Urinary excretion of calcium

E. Expression of calbindins

Which of the following is not involved in regulating plasma Ca²⁺ levels?

A. Kidneys

B. Skin

C. Liver

D. Lungs

E. Intestine

1,25-Dihydroxycholecalciferol affects intestinal Ca²⁺ absorption through a mechanism that

A. includes alterations in the activity of genes.

B. activates adenylyl cyclase.

C. decreases cell turnover.

D. changes gastric acid secretion.

E. involves degradation of apical calcium channels.

Which of the following would you expect to find in a patient whose diet has ...