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## Thermo Regulation - Skin contains thermo receptors and sweat glands. - Sweat glands release sweat, which cools the skin as it evaporates. - This helps lower your internal temperature. ### Body temperature control under normal conditions - Sweat evaporates from the skin, providing a cooling eff...

## Thermo Regulation - Skin contains thermo receptors and sweat glands. - Sweat glands release sweat, which cools the skin as it evaporates. - This helps lower your internal temperature. ### Body temperature control under normal conditions - Sweat evaporates from the skin, providing a cooling effect. - Body temperature rises as a result of heat. - Skin temperature rise enhances heat exchange from the body to the environment. - Body temperature is controlled via sweating and skin temperature rise by increasing blood flow. - Exertion and exercise produce heat, which in turn increases body temperature. ## Synthesis of Vitamin D - Keratinocytes of the skin are unique in being not only the primary source of vitamin D for the body, but in possessing both the enzymatic machinery to metabolize the vitamin D. - **Steps in Vitamin D Synthesis:** - **Sun:** UVB radiation - **Skin:** Vitamin D Precursor - **Liver:** 25 (OH)D - **Kidney:** 1.25 (OH)D - Active Vitamin D - **Cholecalciferol (D3)**: Chemical formula - $CH_3$ - $CH_3$ - $CH_3$ - $CH(CH_3)_2$ - $CH_2$ - $CH_2$ - $CH_2$ - $CH$ - $CH_2$ - $CH_2$ - $CH_2$ - $CH_2$ - $CH$ - $CH$ - $CH_2$ - $CH_2$ - $CH_2$ - $CH_2$ - $CH$ - $CH_2$ - $CH_2$ - $CH$ - $CH_2$ - $CH_2$ - $CH$ - $CH_2$ - $CH_2$ - $CH_2$ - $CH_2$ - $CH_3$ - $CH_3$ - $CH_3$ - $OH$.