The nature of skin pigmentation
The colour of the skin depends on its pigmentation and can vary form very dark brown skin to a almost white and colourless and it depends on the dark pigment called melanin which is produced by skin cells called melanocytes situated in the base of epidermis.
All the skin types (African-American, Asian, European, Caucasian etc.) have the same structure. Human skin consists of the three layers: epidermis, dermis and fatty layer. Epidermis is the first one outer skin layer, dermis is the middle one structural layer and fatty layer is the innermost one. These skin layers constantly interact and produce skin features such as complexion and texture.
As it was said, melanin is located in the epidermis or outermost skin layer and is produced by specialized skin cells called melanocytes. All the people have melanin in their skin but the number and size of the pigment particles can differ. There are also two forms of melanin — pheomelanin and eumelanin. Pheomelanin is mostly found in the skin of light complexioned people has red to yellow colour while eumelanin has brown to black colour and it’s mostly found in the dark skin.
Melanin protects our skin form the ultraviolet radiation by absorbing it and transforming into harmless heat. This property of melanin helps to prevent sunburn damage and numerous skin disorders caused by sun radiation. Due to the fact that in the tropical latitudes the ultraviolet radiation is the most intensive, people there have darker skin by nature.
Our skin also can change its colour depending on the amount of sun radiatin igets. It happens in the summer when the amount of sun radiation increases and our skin seasonaly changes its colour into the darker one. This ability of the skin is usually called tanning. When our skin tans the amount of melanin in its cells increases.
Tanning process is divided into two processes: darkening of the melanin that already produced in the skin and increasing of the production of new melanin particles which causes delayed skin tanning within 3 days after the sun exposure.
Hyperpigmentation is the darkening of a certain skin areas, dark skinned people with African, Asian, and Mediterranean skin types are more prone to it. Hyperpigmentation can be caused by skin inflammations, sun damage, skin injuries, scars etc. The reason of hyperpigmentation is an excess melanin production in the skin cells.