3 which of the following is not involved in

3. Which of the following is not involved in regulating plasma Ca 2+ levels?
A. Kidneys
B. Skin
C. Liver
D. Lungs
E. Intestine
(inactive form) using 24-Hydroxylase.
•
Skin : sunlight activates 7-Dehydrocholesterol into
Vitamin D3 (cholecalciferol)
•
Liver : converts Vitamin D3 (cholecalciferol) to 25-
Hydroxycholecalciferol with the use of 25-Hydroxylase
•
Intestine : increases absorption of calcium in response to
increased vitamin D level
ANSWER: D
•
Kidneys : converts 25-Hydroxycholecalciferol into
1,25-Dihydroxycholecalciferol (active form) using
1α -Hydroxylase and 24,25-Dihydroxycholecalciferol
Ganong. Review of Medical Physiology 23rd ed. Chapter 23, page 366
4. 1,25-Dihydroxycholecalciferol affects intestinal Ca2+ absorption
through a mechanism that:
ANSWER: A
Ganong. Review of Medical Physiology 23rd ed. Chapter 23 , page 365
5. Which of the following would you expect to find in a patient whose
diet has been low in calcium for 2 months?
•
Increased formation of 1,25 dihydroxycholecalciferol
•
Increased amounts of calcium-binding protein in
intestinal epithelial cells
•
Increased parathyroid hormone secretion
•
A low plasma calcitonin concentration
•
Decreased
plasma phosphate
Ganong. Review of Medical Physiology 23rd ed. Chapter 23 , page 368