abrasion is a partial thickness wound that is caused by the damage to the skin and can be superficial involving only the epidermis to deep, involving the deep dermis. Abrasions usually involve minimal bleeding. Light friction, also known as grazing or scrap, does not cause stains or bleeding because the dermis is intact, but deep friction marks which inhibit normal dermal structures can cause tissue formation. More painful friction that removes all the skin layers is called aviation.
Safety is provided by mechanical injury, chemical threats and bacterial invasion by the skin because the epidermis is relatively thick and is covered with keratin. Secretaries Cebcius glands and sweat glands also benefit this protective barrier. In the case of an injury that damages the protective obstruction of the skin, the body is called a healing reaction. After hemostasis, swelling in white blood cells, Phagocytic reach the injury site including macrophages. Once the invading microorganisms are in control, the skin moves forward to cure itself. Despite significant damage, the ability to heal the skin is due to the presence of stem cells in the dermis and the presence of cells in the stratum basal of the epidermis, which can produce all new tissues.
When an injury spreads into the dermis through the epidermis, bleeding occurs and inflammatory reaction begins. The system of clotting in the blood is activated soon, and the crust becomes within several hours. The scab temporarily restores the integrity of the epidermis and restricts the entry of microorganisms. After the scab is formed, the cells of the stratum baseline begin to divide through the mitosis and move to the edges of the scalp. After one week of injury, the edges of the wound are pulled together by contraction. Contraction is an important part of the healing process when the damage has become widespread, and the inherent contraction involves shrinking in the connective tissue, which brings the wound margin in each other. In a major injury, if epithelial cell migration and tissue contraction cannot cover the wound, connecting the injured skin edges together, or even for the replacement of lost skin with skin grafts, skin May be necessary to restore.
Since epithelial cells revolve around the scalp, repair of dermis occurs from the activity of stem cells. These active cells produce collagenous fiber and ground substances. Blood vessels soon develop in the dermis, restore circulation. If the injury is very minor, epithelial cells eventually restore epidermis, once the dermis is reproduced.
In major injuries, repair mechanisms are unable to restore the skin to its original state. In the repaired area there are unusually large number of collagenous fibers and relatively few blood vessels. Damaged sweat and sore glands, hair follicles, muscle cells and nerves are rarely repaired. They are usually replaced by fibrous tissue. The result is a rigid, fibrous scar tissue formed.