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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 start an orderly set of events that are involved in the healing response, in which the normal functional tissue (skin) is replaced by connective tissue (scar). The healing response is also characterized by the migration of specialized cells into the injury 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. The beauty of our organism is that it has the sophisticated capacity to restore that structure by replacing exactly what was there before the injury. Lower forms of life, such as the salamander and crab, can regenerate tissue in this manner. As man has evolved, we have lost this capacity and can only replace a limited amount of damaged 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 creation and scar remodeling. This is the usual response that most humans experience following an injury. The pathological response to tissue injury stand in sharp contrast to the healthy repair response.

3. Excessive healing (fibrosis and contractures)

In excessive healing there is an exaggerated accumulation of connective tissue that results in altered structure and, thus, loss of functionality. Fibrosis, structures, adhesions and contractures are consequences of exaggerated healing. Keloids and hypertrophic scars in the skin are examples of fibrosis. Contraction is normal during the 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 exists when there is an abnormally low deposition of connective tissue matrix and the tissue is weakened to the point where it can fall apart. Chronic non-healing ulcers are examples of deficient healing.

The Skin's Own Scar Healing Process

Just as an injury occurs, several different cells are sent to the damaged site, and the complex healing process begins.

The normal healing cascade commences with an coordinated process of hemostasis and fibrin accumulation, which initiates an inflammatory cell cascade, characterized by neutrophils, macrophages and lymphocytes within the damaged tissues. This is followed by migration and synthesis of fibroblasts and collagen accumulation, and finally remodeling by collagen cross-linking and scar maturation. Despite this coordinated sequence of events leading to normal wound healing, pathologic responses leading to fibrosis or chronic ulcers may occur if any step of the healing sequence is altered.