Question

The skin begins the production of vitamin D in which of the following situations? When

A. exposed to ultraviolet radiation.
B. signalled to by the hormone PTH
C. calcium is present
D. it adds an hydroxyl group to a cholesterol molecule.

Answer 1

The skin begins the production of vitamin D when exposed to ultraviolet radiation from sunlight. Vitamin D is important for the absorption of calcium and phosphorous, which are essential for healthy bones.

Step-by-step explanation:

The skin begins the production of vitamin D when exposed to ultraviolet radiation from sunlight. When sunlight hits the skin, a form of vitamin D3 called cholecalciferol is synthesized from cholesterol present in the skin. This cholecalciferol is then converted to calcidiol and calcitriol in the liver and kidneys, respectively, which are the active forms of vitamin D. Vitamin D is important for the absorption of calcium and phosphorous, which are essential for healthy bones.