PTH Physiology

Multiple Choice

Which of the following promotes calcium absorp­tion principally by increasing, over a period of about 2 days, the formation of calbindin, a calcium­ binding protein, in the intestinal epithelial cells?

• Vitamin D

• Calcitonin

• Phosphate

• IL-1

Multiple Choice

Normal values of calcium and phosphate in adults:

• 8.4mg/dL

  4mg/dL

• 7.4mg/dL

  5mg/dL

• 9.4mg/dL

  4 mg/dL

• 10.4mg/dL

  5 mg/dL

Match

Match the following options related to calcium exchange:

• Calcium intake per day

• Absorption

• Secretion

• Bone

• Kidneys excretion

1000 mg

350 mg

250 mg

1,000,000 mg

100mg

• 1000 mg

• 350 mg

• 250 mg

• 1,000,000 mg

• 100mg

Multiple Choice

Which of the following represents the active form of vitamin D?

• Cholecalciferol

• 25-Hydroxicolecalciferol

• 1,25-Dihydroxicholecalciferol

• 24,25-Dihydroxicholecalciferol

Multiple Choice

How do you explain the graph?

• Higher levels of 1,25-dihydroxycholecalciferol are produced when calcium levels are low to increase calcium absorption in the intestines.

• Higher levels of 1,25-dihydroxycholecalciferol are produced when calcium levels are high to decrease calcium absorption.

• There is no relationship between 1,25-dihydroxycholecalciferol production and calcium levels; it remains constant regardless of calcium levels.

• 1,25-dihydroxycholecalciferol production decreases as calcium levels decrease to conserve calcium.

Multiple Choice

How do you explain the graph?

• High levels of 25-hydroxycholecalciferol inhibit the activation of more vitamin D3 through negative feedback mechanisms.

• Low levels of 25-hydroxycholecalciferol stimulate the liver to produce more vitamin D3.

• High levels of 25-hydroxycholecalciferol promote the activation of vitamin D3 to increase calcium absorption in the intestines.

• The graph suggests that 25-hydroxycholecalciferol has no impact on the regulation of vitamin D3 activation.

Multiple Choice

Select the right sentence in relation with PTH:

• PTH increases calcium and decreased phosphate absorption from the bone

• The PTH increases the excretion of calcium by the kidneys

• The decline in phosphate concen­tration is caused by a strong effect of PTH to increase renal phosphate excretion

• PTH inhibits the formation of 1,25-Dihydroxicholecalciferol

Multiple Choice

Which of the following is a correct sentence in relation to calcitonin?

• Decrease the absorptive activities and the osteolytic effect of the osteocytic membrane

• Increase the formation of new osteoclasts

• The effect of calcitonin in children is minimal because bone remodeling occurs slowly in them

• Any reduction of the calcium ion concentration by calcitonin leads to a suppression of PTH secretion

Quiz Time!

PTH26