8) Endocrine Regulation of Blood Calcium - Vitamin D

What is the active form of vitamin D in the human body?

1,25-dihydroxycholecalciferol

What enzyme is stimulated by parathyroid hormone to activate vitamin D in the kidneys?

1-alpha hydroxylase

What triggers the synthesis of 24,25-hydroxycholecalciferol?

High blood calcium levels

What is the primary function of calcitriol (active vitamin D)?

Enhancement of intestinal calcium absorption

Which molecule is synthesized in the skin following exposure to sunlight?

Cholecalciferol

What protein does calcitriol upregulate in enterocytes to facilitate calcium absorption?

Calbindin

What condition is caused by vitamin D deficiency in adults?

Osteomalacia

Which of the following statements about osteoporosis is TRUE?

It occurs when bone resorption exceeds bone deposition.

What type of exercise is recommended to reduce the risk of osteoporosis?

Weight-bearing exercise

What is the main function of 24-hydroxylase?

Production of inactive vitamin D