The skin may appear just to be an outward body covering, but it is the largest organ in the body. The average surface area of the skin varies from 1-5-2.0 sq meters. The skin is a complex organ and plays a vital role in daily body functions.
The skin is essentially composed of 3 basic layers:
Epidermis: This outer layer provides a protective covering against infections, trauma and is waterproof. The epidermis varies in thickness from 0.05 mm (eyelids) to 1.5 mm (soles and back). It has no blood vessels and thus relies on nourishment from the structures below it. It does contain a few specialized cells which include:
- Melanocytes- which make melanin
- langerhan cells- which act as scavenging cells
- keratinocyes- protect against infections and trauma
The outermost layer of epidermis is made up of several layers of dead cells.
Dermis: This is the layer immediately beneath the epidermis and contains an assortment of cells and tissues. It basically provides cushioning from trauma and plays a vital role in maintaining the elasticity of the skin. It has many nerves, glands and blood vessels. It is subdivided into two layers- papillary and reticular layers.
Subcutaneous tissue: This layer below the dermis attaches to the bone, muscles and large blood vessels. It also contains numerous cells and tissue types. Besides forming a cushion against trauma and pressure, it also provides nourishment to the rest of the skin. The majority of fat in the skin is found in this layer.