CALCIUM PHOSPHATE HOMEOSTASIS

1.Which of the following statements best describes homeostasis?

• a) Keeping the body in a fixed and unaltered state.

• b) Dynamic equilibrium.

• c) Maintaining a near-constant internal environment.

• d) Altering the external environment to accommodate the body's needs.

2.A small Ca binding protein that modifies the activity of many enzymes and other proteins in response to changes of Ca2+ concentration, is known as:

• a) Cycline

• b) Calmodulin

• c) Collagen

• d) Kinesin

3. Which of the following hormone interact to regulate 1α-hydroxylase activity

• a) Parathyroid hormone

• b) calcitriol

• c) calcitonin

• d) thyroid hormone

4.Which of the following hormones is not important in calcium homeostasis?

• a)Calcitonin

• b) Parathyroid hormone

• c) 1,25-dihydroxycholecalciferol

• d) Glucagon

5.Which of the following statements regarding calcium homeostasis is not true?

• a) Extracellular calcium concentration is monitored in the parathyroid.

• b) Inhibition of osteoclast activity helps restore high extracellular calcium concentration to normal levels.

• c) Calcitonin and parathyroid hormone have opposing effects on extracellular calcium concentration.

• d) 1,25-dihydrocycholecalciferol and parathyroid hormone have opposing effects on extracellular calcium concentration.