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When we are small, we usually have to endure many different types of injuries such as burns, cuts, and knocks or bangs in our body. These injuries become less during adulthood, but we still sustain them well. How is it possible? Well, all of these aggressions commence an orderly sequence of steps that are involved in the healing response, in which the normal healthy tissue (skin) is replaced by connective tissue (scar). The healing response is also characterized by the movement of specialized cells into the wound site.

Healing is the complex and dynamic process that results in the restoration of anatomical continuity and function. After an injury, your body can respond in 4 different ways:

1.Regeneration (exact replacement)

Regeneration happens when there is loss of structure and functionality. Our body is so incredible, that it has the complex ability to restore that structure by replacing exactly what was there before the damage. Lower forms of life, such as the salamander and crab, can regenerate tissue in this manner. Throughout the past million years, we have lost this ability and can only replace a limited amount of injured tissues by the process of regeneration.

2. Normal repair (reestablished equilibrium)

Normal repair is the instance where there is a re-established equilibrium between scar formation and scar remodeling. This is the usual response that most humans experience following an injury. The pathological response to tissue damage stand in sharp contrast to the healthy repair response.

3. Excessive healing (fibrosis and contractures)

In excessive healing there is an exaggerated deposition of connective tissue that results in altered structure and, thus, loss of functionality. Fibrosis, structures, adhesions and contractures are examples of exaggerated healing. Keloids and hypertrophic scars in the skin are examples of fibrosis. Contraction is part of the normal process of healing but if exaggerated, it becomes pathologic and is known as a contracture.

4. Deficient healing (chronic ulcers)

Deficient healing is the opposite of fibrosis; it appears when there is an abnormally low deposition of connective tissue matrix and the tissue is thinned to the point where it can fall apart. Persistent non-healing ulcers are examples of deficient healing.

The Scar Healing Process

When an injury occurs, a movement of different cells comes immediately and the complex healing process just begins in the moment it's happened.

The normal healing cascade begins with an coordinated process of hemostasis and fibrin deposition, which leads to an inflammatory cell cascade, characterized by neutrophils, macrophages and lymphocytes within the tissue. This is followed by migration and synthesis of fibroblasts and collagen deposition, and finally remodeling by collagen cross-linking and scar maturation. Despite this coordinated sequence of steps responsible for normal wound repairing, abnormal reactions leading to fibrosis or chronic ulcers may occur if any part of the healing cascade is altered.