Skin structure and wound healing
Skin structure and wound healing
Skin consists of three main layers, the outer epidermis, the underlying dermis, and the deep follicles hypodermis.
The epidermis
The epidermis has five layers. Cells at the base, the basal cell layer, divide continually pushing the older cells towards the surface where they are eventually shed. A gradual process transforms the round, nucleated cells of the basal layer into the flattened, keratin-rich ones found on the outer surface of the epidermis. This top layer of dead skin cells, called the “stratum corneum”, is where Strataderm dries and bonds to form a silicone gel sheet. This is a protective water proof barrier that retains moisture, is gas permeable and assists the skin to continue to expel “breath”. Repair of damaged epidermis occurs by regeneration. The cells of the basal layer multiply and migrate from undamaged areas to replace damaged cells. The eventual repair has a normal structure and appearance and leaves no visible scar.
The dermis
The dermis consists of collagen and elastin fibres, supplied by a rich network of small blood vesicles. The dermis supports the epidermis. Dermal elastin supplies the elasticity and collagen provides the tensile strength of the skin. Specialised skin structures such as hair follicles, sebaceous and sweat glands also lie within the dermis.
Repair of damaged dermis is dependant on the level of trauma. Healed superficial dermal damage may be clinically indistinguishable from normal skin. Full-thickness damage to the dermis is repaired by a process called granulation and can result in the formation of a permanent, visible scar.1
The hypodermis
The dermis is attached to the underlying loose tissue called the hypodermis. This layer consists of various amounts of adipose, or fat tissues as well as specialised skin structures that are also found in the dermis above.
1 Bayat A et al. BMJ 2003; 326:88–92
