The healing of the skin, a response to damage
caused by cuts or burns, is one of the amazing features of the
human body. This process is vital to the functions f the skin,
allowing it to maintain the delicate balances within the body.
Without healing, the skin is open to disease causing microbes
and water loss.
Although there are numerous ways to cut the skin, all healing follows the same basic mechanism of 4 steps:
Phase 1: The blood vessels in the surrounding tissue constrict, reducing the flow of blood at the injury. Specialized cells in the blood, called platelets, release chemicals causing proteins in the blood to form a mesh-like network. The mesh traps blood cells, forming a blood clot that plugs the torn blood vessels. Another group of cells, mast cells, release histamine, which attracts phagocytic white blood cells. This initiates inflammation, which allows for combating any infection that may arise.
Phase 2: Within hours, the cells of the Stratum basale and the dermis begin dividing, slowly filling in the space created by the injury. New blood vessels are formed to replace those injured, and as the clot dries, it shrinks, pulling the damaged skin closer together, reducing the gap, thus healing can occur faster.
Phase 3: After several days, the phagocyte count remains high as it continues to fight infecton. Under the scab, the epidermis has completed it's proliferation, but healing in the dermis continues.
Phase 4: After 1 to 2 weeks, the scab falls of, revealing the healed skin in a shallow depression. Normally, the dermis continues to grow, and the hollow space below eventually fills. Healing is then complete.
Burns are caused by many things. Obviously heat and steam are frequent culprits. Caustic chemicals (like acids), radiation (in particular solar) or strong electrical current are all excellant sources of burns. The severity of a burn is determined by the size of the surface and the depth of skin damaged. The "Degree" of burn is based on the number of layers damages, 1, 2, or 3; First-degree, second-degree, or third-degree.
First-degree burns are limited to the epidermis. A sun burn, with it's redness, pain and swelling is an excellant example. Short term exposure to hot or cold can also cause these minor burns. Because damage is minor and limited to the surface epidermis, no special treatment is required. The cells of the Stratum basale are undamaged and will divide as normal and quickly replace the damaged ones. Normally scaring does not occur. Treatment with cold water is useful for reducing pain.
Second-degree burns involve the entire epidermis and some of the dermis. Redness, considerable pain, and blistering are all symptomatic. Blistering occurs as the epidermis is pulled away from the dermis, with fluid forming inbetween. Often blisters will break, providing a route for infection to occur. Because of the damage to the epidermis, repair originates in the untouched dermis, particularly from the epithelium surrounding hair follicles and glands. Second-degree burns can damage hair follicles, glands and sensory structures, thus reducing the overall ability to repair the skin. Scarring may occur. Initial treatment with cold water can be followed with a dilute salt solution to help reduce infection.
Third-degree burns involve damage to all three layers of skin, and may even extend deeper. The burned area may be red, white or charred black, and there is extensive fluid loss to the tissue. The center of the burn may be relatively painless due to destruction of the sensory receptors, the margins can be quite painful.
These burns can be easily infected. When the burn covers a large area, it represents a real challenge to the bodies attempts to maintain a balanced internal environment due to the severe loss of fluids and blood. Burns to this magnitude are quite serious and even life threatening. Needless to say, healing is difficult and extensive scaring may form, distorting the skin, making it more inflexible. Movements can become cumbersome. Successful treatment usually requires an aseptic environment to keep patients in a sterile environment, antibiotics to help fight any infection, fluid replacement to prevent dehydration and shock, and frequently skin grafts. These grafts may come from another region of the body, or in very serious conditions, from a donor. The fluids from the body that leak out through the injury actually act to supply the graft with nutriments until new vessels can form. The epithelial cells of the grafts' dermis begin forming new skin.