Question

______ light from sunshine acts on a ______ compound in the skin. The compound is then transformed into a vitamin D precursor and is absorbed directly into the ______. slowly over the next day and a half, the _____ and ____ finish converting the inactive precursor to active form of Vit D

Answer 1

Ultraviolet light from sunshine stimulates a cholesterol-derived compound in the skin to become a vitamin D precursor that enters the bloodstream. The liver and kidneys then convert this precursor into the active form of vitamin D, essential for calcium and phosphorus absorption and bone health.

Step-by-step explanation:

Ultraviolet (UV) light from sunshine acts on a cholesterol-derived compound in the skin. The compound is then transformed into a vitamin D precursor and is absorbed directly into the bloodstream. Slowly over the next day and a half, the liver and kidneys finish converting the inactive precursor to the active form of Vitamin D.

The skin's epidermal layer synthesizes vitamin D when exposed to UV radiation. Specifically, the steroid cholesterol derivative, 7-dehydrocholesterol, in the skin is converted to cholecalciferol, also known as vitamin D3. This vitamin D3 is then converted in the liver to 25-hydroxycholecalciferol, or calcidiol, before being further metabolized in the kidneys by the enzyme 25(OH)D3-1-hydroxylase to 1,25-Dihydroxycholecalciferol, the active form of vitamin D, also known as calcitriol.

Vitamin D is crucial for several physiological processes, including the absorption of calcium and phosphorus for healthy bones, as well as immune system function. A deficiency in vitamin D can lead to conditions like rickets in children and osteomalacia in adults, underscoring the importance of adequate sun exposure or supplementation through diet.