Question

Choose the correct order of steps for the synthesis of Vitamin D.

Answer 1

Answer:

The correct answer will be option-

1. UV light strikes the skin and converts a steroid molecule into an inactive form of vitamin D.

2. Inactive vitamin D is transported to the liver where it is modified.

3. Vitamin D is activated under the influence of PTH.

4. Inactive, chemically altered vitamin D is transported to the kidneys.

Explanation:

Vitamin D is a fat-soluble metabolite which helps maintain the health of the bone by maintaining the calcium homeostasis.

The vitamin D is synthesized mainly in the liver and kidney from the biologically inactive precursor of vitamin D called ergocalciferol and Cholecalciferol.

The inactive vitamin is synthesized in the skin when the skin is exposed to UV rays.  The UV rays convert the 7-dehydrocholesterol, a steroid molecule to Vitamin D3, This inactive vitamin is then transported to the liver where it is converted to 25-hydroxyvitamin D.

This vitamin D form is further metabolized in the kidney controlled and regulated by the Parathyroid glands.