a. A wound occurs and the elasticity of the skin and spasm of muscle cause the initial wound to become larger.

The healing process begins. A blood clot forms, contracts, dries, and forms a scab. This is the first protective covering of the wound.

Next, the inflammation process begins. In the inflammation process, the blood supply to the injured area increases and substances of leukotoxin and histamine are released by the injured cells to promote repair and regrowth of tissues. Leukotoxin draws white
blood cells to the area; these cells destroy and remove foreign substances. Histamine and other substances increase the permeability of the capillary walls allowing fluids, proteins, and white blood cells to move into the injured area. Inflammation is the best environment for wound healing. A problem occurs only if foreign matter remains in the wound.

b. Twelve hours after injury, epithelialization begins. In this phase of wound healing, epithelium forms over the wound. If the wound is superficial, epithelium forms in a few hours. In a deep wound, epithelialization may take days or weeks. At the same time granulation tissue is present, tissue made of fibrous-collagen and capillary loops. This tissue provides excellent protection from infection. At this stage, the wound appears pink (due to the new capillaries in the granulation tissue), and the area is soft and tender. Collagen, a supportive protein component of skin, changes from a liquid to a gel to scar tissue. The wound becomes stronger for seventeen days at which time 90 percent of the wound’s strength has been regained.