How does skin heal wounds?

The largest organ of the body is not the liver or the brain but the skin, with a total area of ​​about 2 square meters in adults . Although different skin areas have different properties, most skin surfaces perform tactile and sweat functions. But after a serious injury, the healed area will look different from the surrounding area and may not be able to fully recover from the original appearance for some time. To understand why, we need to look closely at the structure of human skin.

The top layer, called the epidermis, consists of most solid cells, also known as keratin cells (horny layers) and has a protective function. Because this outer layer of cells will flake and be renewed constantly, they easily heal. But sometimes, we find wounds that penetrate deep into the dermis where many blood vessels, oily glands, sweat glands and the nervous system help the skin to perform many functions.

4 regeneration stages are activated when the skin is injured

First , the hemostatic phase, the skin overcome 2 risks of blood loss and skin damage by the mechanism of creating blood clots in the affected area, limiting blood loss, and patching damaged skin. A form of protein called Fibrin, which forms a knot on the surface of the skin, holds the clot in place and prevents it from invading bacteria and pathogens.

After about 3 hours, the skin begins to redden the signal to start the next phase: Anti-inflammatory . With controlled blood loss, the barrier is reinforced. The body mobilizes cells that attack invading pathogens. The white blood cells swallow and destroy foreign bacteria cells, in addition, they also produce a wound healing stimulus and because these "warriors" need to be moved throughout the bloodstream to reach the wound. The spasm of the blood vessel will first dilate.

About 2-3 days after the injury, the third stage of proliferation begins with the entry of fibrous cells into the wound . They produce a protein called Collagen at the site of the wound, creating connective tissue that replaces the original Fibrin. When the cells of the epidermis divide to create new skin, the epidermis shrinks to close the mouth of the wound.

Finally, stage 4 of the reorganization, the wound heals as the Collagen arranges and transforms into special forms. This process takes about a year, the strength of the new skin will be improved, blood vessels and other bonds will be strengthened firmly. As time goes by, the new tissue can reach 50-80% of its original normal function, depending on the severity of the wound and the function in that area. But because the skin does not recover completely and leaves scars, this is a problem that makes doctors around the world have headaches and look for causes.

Although researchers have taken important steps toward understanding the healing process, there are still many unknown issues. For example, are the fibroblasts coming from blood vessels or tissue in the skin near the wound? Why in other animals like deer, dogs, . wound healing is more effective and perfect than humans? By finding answers to these problems, we hope that in the future we can heal wounds effectively and scars are only memories.

2. Why do wounds often itch when they're healing?
3. How does the wound heal?