Vitamin D is unique in that it can be obtained by the diet but also is synthesized inside the body when a cholesterol-like substance is activated by sunlight and converted to the prohormone vitamin D. Check all of the organs that participate in vitamin D synthesis as a result of sunlight exposure. Check all that apply.

1. Kidneys
2. Skin
3. Bone
4. Liver

Vitamin D is a group pf fat soluble vitamins particularly important for the intestinal absorption of calcium, iron and magnesium.
Vitamin D regulates the absorption of calcium into the intestines and bones, promotes bone formation and normal function of the parathyroid gland.
Vitamin D is synthesized and activated in three steps:
The skin synthesizes Vit D upon exposure to sunlight. However, this form of Vit D, cholecalciferol is not biologically active.
Cholecalciferol is modified to 25hydroxycholecalciferol in the liver.
The final hormonally active form 1,25 dihydroxycholecalciferol is produced in the kidneys.