What are the functions of the skin?

The skin is classified as an organ because it has specific functions in the body such as regulation of body temperature and protecting other organs from harmful bacteria, chemicals, and temperature which requires some specialized tissues. It is also able to receive sensory information which allows for discrimination of pressure differences. This organ also helps to store vitamin D, water, and fat. During exposure to sunlight, 7-dehydrocholesterol in the skin absorbs UVB radiation in the epidermis and keratinocytes convert it to previtamin D3, which then isomerizes into vitamin D3. The skin also contains secretions which neutralize bacteria and the pigment melanin has a pigment defense against UV light which can damage skin cells. It is soft enough to allow movement, but still rigid enough to resist breaking or tearing, making it an ideal barrier to foreign substances. It also varies in thickness and texture in different parts of the body.