The hair follicle's epithelium is derived from the epidermis and is similarly radiosensitive. As a result, the follicular cells may develop an acute dermatitis, or hyperpigmentation earlier than other cells in the dermis. The skin provides the body with an airtight and waterproof covering. Intact skin acts as a barrier to harmful bacteria. Melanin, the skin's pigment, screens harmful rays of the sun.
Skin helps minimize mechanical injury to the underlying structures.
Temperature Regulation Skin helps the body to regulate its own temperature. When the body surface is cold, blood vessels in the skin contract and force the blood deeper into the body. This prevents the body from losing excessive heat. When the body is too warm, the same blood vessels expand and bring more blood to the surface of the skin allowing the body to lose heat. Sweat glands further aid in cooling the skin by producing perspiration which subsequently evaporates.