Skin Function: Regulation
The dermis is the layer of skin under the epidermis, and it's made up mostly of soft tissue such as collagen, elastin and fibrillin -- tissues that make your skin elastic and flexible yet strong and structurally firm. The dermis layer also contains blood vessels, hair follicles, nerve endings, oil glands and sweat glands. It's the latter of these that makes the dermis so important to heat regulation. The dermis controls body temperature through the production of sweat and the control of evaporation -- a process known as insensible perspiration. Basically, the sweat glands of the dermis secrete sweat, which then evaporates on the surface of the skin. Because evaporation requires heat to work, the process of evaporating sweat actually helps to lower the temperature of your skin [source: P&G].
The dermis also regulates temperature by controlling red blood cells. When the body is cold, the red blood cells of the dermis contract, which helps to retain internal body temperature. When the body is hot, the red blood cells expand, allowing heat to be released through the surface of the skin [source: The Merck Manuals].
The subcutaneous layer is made up of fat cells and fibrous tissue [source: The Merck Manuals]. Like the dermis, the subcutaneous layer helps to regulate body temperature. In this case, however, it provides insulation against the absorption of cold and the loss of heat [source: P&G].
The skin doesn't stop there with protection and regulation. It also provides you with one of your most useful senses -- the sense of touch. To learn more about how the skin influences your senses, read the next page.