Protection from mechanical injury, chemical hazards, and bacterial invasion is provided by the skin because the epidermis is relatively thick and covered with keratin.
In the event of an injury that damages the skin's protective barrier, the body triggers a response called wound healing.
After hemostasis, inflammation white blood cells, including phagocytic macrophages arrive at the injury site.
Contraction is an important part of the healing process when damage has been extensive, and involves shrinking in size of underlying contractile connective tissue, which brings the wound margins toward one another.
Damaged sweat and sebaceous glands, hair follicles, muscle cells, and nerves are seldom repaired.