Physiology: Calcium Homeostasis and Regulation

Question 1

How is calcium homeostasis regulated?

Answer 1

By the effects of PTH and 1,25-dihydroxyvitamin D3 on the gut, kidney and bone

Question 2

What is the primary source of vitamin D in humans?

Answer 2

Photoactivation in the skin of 7-dehydrocholesterol to cholecalciferol

Question 3

What is the active form of vitamin D found in humans?

Answer 3

1,25-dihydroxyvitamin D3

Question 4

Name the hormone which increases plasma calcium through many mechanisms, including increasing osteoclastic activity in bone and increasing intestinal absorption of calcium

Answer 4

PTH