What Is a Scar?

After an injury, the process of healing may result in a scar.

When your body first sense a cut, it reacts by constricting blood vessels to minimize blood loss. As your blood clots over the damaged area, chemotactic factors, substances associated with the body’s inflammation response, and growth factors, substances that aid in inducing cell growth and differentiation, are pumped to the site of the wound. This results in both inflammation and an influx of immune cells to help deal with the problem.

Your body slowly begins to dissolve the clot, introducing new cells that will form the basis of your scar. In particular, fibroblasts, a type of cell that stimulates collagen growth, arrive on the scene. Fibroblasts lay down tissue, adding fibers and contracting the scarred area.
Fibroblasts

Like the tissue that it is replacing, scar tissue stimulated by fibroblasts is made out of collagen. However, the fiber composition of the collagen is different than that of healthy skin. Normal collagen fibers are in a sort of basket weave-style formation. In scar tissue, though, the collagen goes only in a single direction. Thus, it looks different from your normal skin.

scar on arm

Scar tissue is typically inferior to normal tissue in a variety of ways. For example, scars are less resistant to UV radiation than undamaged skin.

This same process can happen in acne-prone skin when zits are popped unsafely, signalling to your body that a wound has occurred. Stretch marks are also a form of scarring caused by tearing the dermis.