How Wounds Heal

How Wounds Heal

Most of us take wound healing for
granted. If you get a small cut, you may clean and cover it with a bandage, and move on
with your life. Yet under that bandage (or in the open air), the body orchestrates a
complex cascade of events designed to heal wounds big and small.

The basic steps of wound healing
are:

  1. Stopping the bleeding (hemostasis).
    When your skin is cut, scraped, or punctured, you usually start to bleed. Within
    minutes or even seconds, blood cells start to clump together and clot, protecting the
    wound and preventing further blood loss. These clots, which turn into scabs as they
    dry, are created by a type of blood cell called a platelet. The clot also contains a
    protein called fibrin, which forms a net to hold the clot in place.

  2. Inflammation. Once the wound is
    closed with a clot, the blood vessels can open a bit to allow fresh nutrients and
    oxygen into the wound for healing. 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.

  3. Growth and rebuilding. Blood
    cells, including oxygen-rich red blood cells, arrive to help build new tissue.
    Chemical signals tell the cells to create collagen. It serves as a type of
    scaffolding. Occasionally, you see the result of this process as a scar that starts
    out red and eventually dulls. 

  4. Strengthening. Over time, the
    new tissue gets stronger. You might notice stretching, itching, and even puckering of
    the wound as that happens. The wound gains strength quickly over the first 6 weeks of
    healing. In about 3 months, the wound is 80% as strong in its repair as it was before
    the injury. But the wound area will never reach 100% of its original strength.
    Depending on the size and the severity of the wound, the entire healing process might
    take up to a couple of years to complete.

Interrupted wound healing

The process seems simple enough,
but wound healing is really quite complicated and involves a long series of chemical
signals. Certain factors can slow or prevent healing entirely.

One of the most dramatic factors is
reduced or poor blood supply to the wound. The oxygen and nutrients that new blood
carries to the wound are key 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. These are called
chronic wounds, which are more common in elderly people or people with diabetes, high
blood pressure, obesity, or other vascular disease. People who smoke are at high risk
for poor wound healing.

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, warm or hot to the touch, painful, or draining/oozing pus — see a healthcare
provider right away. If you smoke, ask your provider for resources that will help you
quit.