when injured, is capable of repairing itself to restore tissue integrity and heal the wound. This wound healing involves 4 overlapping process, beginning immediately after an injury:
The body works to stop the bleeding and start the healing process by activating a coagulation cascade. A fibrin blood clot forms that plugs severed blood vessels and fills in tissue discontinuity at the wound site.
During this phase, white blood cells and macrophages enter the wound to destroy bacteria and remove debris. The blood clot creates a fibrin scaffold that serves as a protective, provisional extracellular matrix (ECM) containing cytokines and growth factors (interleukin, transforming growth factor-β, platelet-derived growth factor, and vascular endothelial growth factor, among others) that facilitate tissue repair.
The blood clot recruits endothelial cells and fibroblasts to synthesize a permanent ECM. The focus is filling and covering the wound.
The blood clot dries out and becomes a protective scab. Under the scab, tissue remodeling takes place undisturbed. The fibrin is replaced by fibronectin and hyaluronan, and the scab falls off to reveal a collagenous scar.