Dermis
Residing just below the epidermis is the dermis, which constitutes 90% of total skin thickness. Because of its rich collagen content, the dermis is the strength layer of the skin. In addition, it contains blood vessels, nerve endings, hair follicles, and immune cells that act as sentries against infection and cancer.
These two layers are draped over a deeper subcutaneous layer comprised of fatty tissue, blood vessels, and nerves which is generally protected from injury by the overlying epidermal and dermal covering.
Wound Healing
Under normal conditions, the process of healing occurs in three overlapping phases. Roughly speaking, these are divided into inflammatory, proliferative, and remodeling phases and involve contraction (downsizing of the wound), epithelialization (creation of new epithelial cells), and deposition of connective tissue.
Inflammation
When skin is injured-whether in a planned injury such as a surgical incision or as the result of trauma-an inflammatory phase begins. This is initiated by the release of several chemicals from both platelets (tiny cells which initiate the clotting mechanism) and the surrounding injured tissue. The site of injury turns red, becomes swollen, and displays all the normal properties we commonly associate with an acute wound.
