Skin

Your skin is your body's largest organ with a surface of 1½ - 2 m2. Skin is made up of very specific cells and tissues and their collective purpose is to act as boundaries between you and the outer environment, that is the skin is your body’s major barrier against external environment i.e. chemicals and illnesses.

There are two main layers of the skin; the Epidermis, which is the outer structure of the skin, and underneath is the Dermis located. Below the Dermis, we find the Hypodermis where fat is stored and where the blood vessels branch off into the Dermis. The epidermis has no direct blood supply but is instead supported and fed by the dermis.

The Malpighian layer is structured like this; closest to the dermis is the basal layer. Above the Basal layer is the Spinous layer and above the Spinous layer is the Granular layer. Living among the basal cells is another type of cells called melanocytes which produce Melanin, the pigment that is the source of tanning.

The Epidermis consists of two layers; the outer layer, the Corneal layer, is made of dead skin cells. In the living inner layer, the Malpighian layer, cells to the corneal layer are formed. It is here that the sun affects the skin during tanning.

Skin cross section

Close-up Epidermis cross section

The appearance of the skin is mainly determined by Melanin, a pigment manufactured by Melanocytes. Their numbers in any one region of the body are roughly the same between races. Colour differences are to a large extent due to the nature of the pigment granules and the amount of Melanin produced. Melanocytes produce two different pigments: eumelanin (brown/black) and phaeomelanin (yellow/red).