In fair skins, melanin gets gradually destroyed as it moves upwards towards the outer layer of the epidermis. In dark skins, the destruction of melanin does not continue as far as the superficial layer. Therefore, the skin surface in dark, such skins contains much more melanin.
As melanin is a dark pigment, the skin surface acquires a dark colour. More the melanin darker the skin. In countries where the climate is hot and sunny, nature has given people dark skins to protect them from UVR. In countries where the climate is cold and very little sun, nature has given the people fair skins.
When there is an excessive secretion of melanin and if care is not taken, there is excessive keratinisation (hardening of skin) caused by the presence of the unexfoliated dead cells on the skin's surface causing more darkening of the skin in patches.
Factors causing skin pigmentation :
The internal disorders that cause pigmentation:
Internal pathological problems can sometimes interfere with the production or transfer of melanin. This may give rise to skin problems associated with colour, in the form of white or dark patches.
Some of these disorders are:
*Pregnancy: Due to hormonal changes, the production and transfer of melanin is affected and dark brown spots appear predominantly on the face.
To Be Continued....
