Melanin pigments that are present in the skin cause the coloration of the skin. These pigments are responsible for the skin tone of the people. Larger quantities of this pigment will result in darker coloration of the skin and smaller quantities means lighter complexion. Caucasians have lesser amounts of melanin in their skin and people with African ancestry have more amounts of this pigment on their skins. Melanin is a cell that offers protection to the skin against damage; it also is responsible for restoration of the skin to its natural tone after the damage has been rectified. When the skin is damaged because of overexposure to sunlight or through wound or by any other means, the body sends more amounts of melanin to the damaged parts.
This excess amount of melanin then works towards restoring the skin tone to an even nature. This is why the skin is darkened during the healing process. Sometimes, the melanin pigments are not capable to restore the skin tone and this result in darker skin pigmentation or dark spots. Skin pigmentation can occur in isolated patches or can appear as a cluster around a small surface area. Skin pigmentation does not mean that all the melanin pigments have lost their ability to function properly; it only means that the pigments present in one particular area are damaged. The rest of pigments present in the other parts of the body can function normally.
There are various reasons that can cause damage to melanin, which can result in skin pigmentation. The primary reason is overwork. Melanin pigments are constantly working. They continue to maintain the even tone in the body, in spite of the skin being exposed to sunlight on a constant basis. Some parts of the body like face, neck, arms, back of the hands, shoulders, back, etc. receive more amounts of sunlight when compared to other body parts. Melanin pigments present in these areas are getting over worked all the time. This results in their break down, which can result in skin pigmentation. Melanin breakdown can also occur due to mal nutrition. If these pigments do not get adequate nutrients, they lose their ability to function. Melanin can also cease its function of the skin is badly damaged. This is why deep wounds have permanent skin pigmentation even after they are healed completely. Skin pigmentation is directly related to the function of melanin pigments.