What vitamin is synthesized in the skin upon exposure to sunlight?

Vitamin D is synthesized in the skin upon exposure to sunlight, specifically ultraviolet B (UVB) radiation. When the skin absorbs UVB rays, a chemical reaction converts 7-dehydrocholesterol, which is present in the skin, into pre-vitamin D3. This is then transformed into vitamin D3 (cholecalciferol) and further processed by the liver and kidneys to become the active form of vitamin D, which plays essential roles in calcium metabolism and bone health.

The production of vitamin D in the skin highlights the importance of sunlight for overall health, illustrating how the integumentary system is vital not just for protection and sensation but also for biochemical processes that affect our metabolism and immunity.