How does wound healing work

But how, exactly, does our body heal? The cascade of healing is divided into these four overlapping phases: Hemostasis, Inflammatory, Proliferative, and Maturation. Hemostasis, the first phase of healing, begins at the onset of injury, and the objective is to stop the bleeding.

In this phase, the body activates its emergency repair system, the blood clotting system, and forms a dam to block the drainage. During this process, platelets come into contact with collagen, resulting in activation and aggregation.

An enzyme called thrombin is at the center, and it initiates the formation of a fibrin mesh, which strengthens the platelet clumps into a stable clot. The 4 phases of wound healing. Healing begins with Hemostasis. During Phase 2, a type of white blood cells called neutrophils enter the wound to destroy bacteria and remove debris. These cells often reach their peak population between 24 and 48 hours after injury, reducing greatly in number after three days. As the white blood cells leave, specialized cells called macrophages arrive to continue clearing debris.

These cells also secrete growth factors and proteins that attract immune system cells to the wound to facilitate tissue repair. This phase often lasts four to six days and is often associated with edema, erythema reddening of the skin , heat and pain. Once the wound is cleaned out, the wound enters Phase 3, the Proliferative Phase, where the focus is to fill and cover the wound. The Proliferative phase features three distinct stages: 1 filling the wound; 2 contraction of the wound margins; and 3 covering the wound epithelialization.

During the first stage, shiny, deep red granulation tissue fills the wound bed with connective tissue, and new blood vessels are formed. During contraction, the wound margins contract and pull toward the center of the wound. Blood-borne oxygen is needed for healing. The right balance of oxygen is also important — too much or too little and the wound won't heal correctly.

Another type of blood cell, a white blood cell called a macrophage, takes on the role of wound protector. This cell fights infection and oversees the repair process. You might see some clear fluid on or around the cut at this time. That is helping clean out the wound. Macrophages also produce chemical messengers, called growth factors, which help repair the wound. Blood cells, including oxygen-rich red blood cells, arrive to help build new tissue. Chemical signals tell the cells to create collagen.

The oxygen and nutrients that new blood carries to the wound are essential to successful healing. A wound that is not getting enough blood could take at least twice as long to heal, if it heals at all. By some estimates, as many as 6. These are called chronic wounds, which are more common in elderly people or people with diabetes, high blood pressure, obesity, or other vascular disease.

If you have a wound that is not healing in a reasonable time frame, make an appointment with your healthcare provider. If your injury seems to be getting worse or appears infected — that is, if it is more swollen, hot to the touch, painful, or oozing pus — see a healthcare provider right away.

Health Home Treatments, Tests and Therapies. The basic steps of wound healing are:. Interrupted wound healing The process seems simple enough, but wound healing is actually quite complicated and involves a long series of chemical signals.

The wound becomes slightly swollen, red or pink, and tender. You also may see some clear fluid oozing from the wound.

This fluid helps clean the area. Blood vessels open in the area, so blood can bring oxygen and nutrients to the wound. Oxygen is essential for healing. White blood cells help fight infection from germs and begin to repair the wound.

This stage takes about 2 to 5 days. Tissue growth and rebuilding occur next. Over the next 3 weeks or so, the body repairs broken blood vessels and new tissue grows.

Red blood cells help create collagen, which are tough, white fibers that form the foundation for new tissue. The wound starts to fill in with new tissue, called granulation tissue. New skin begins to form over this tissue. As the wound heals, the edges pull inward and the wound gets smaller. A scar forms and the wound becomes stronger. As healing continues, you may notice that the area itches.

After the scab falls off, the area may look stretched, red, and shiny. The scar that forms will be smaller than the original wound.

It will be less strong and less flexible than the surrounding skin. Over time, the scar will fade and may disappear completely. This can take as long as 2 years. Some scars never go away completely. Scars form because the new tissue grows back differently than the original tissue.