Skin Colour

Human skin colour has a wide spectrum of colors, ranging from shades of dark brown skin to almost white coloured skin. The colour of our skin is determined primarily by a special pigment called melanin. This is produced by cells called melanocytes. This pigment also helps protect us from ultraviolet light. Generally, the amount of melanin in our skin depends on a combination of inherited factors and degree of light exposure. Other pigments that contribute to skin colour include haemoglobin (oxygen carrying pigment in red blood cells) and carotene (fat-soluble pigments found in green, yellow, leafy vegetables, and yellow fruits).

Melanin

We have special cells in the skin called melanocytes that are responsible for producing melanin. The thing that determines our skin colour is the type and amount of melanin produced. The number of melanocyes is not important. In lighter skinned people, melanin is broken down more quickly. The location of melanin is also important. In darker skinned people, melanin is found through many layers of the skin, including the outermost layers. This allows us to see the skin as darker in colour. Melanin is very important in protecting our skin against the damaging effects of sun light. There are two types of melanin pigment - eumelanin (brown-black colour) and pheomelanin (red-yellow). These are determined by your genes. Exposure to the sun's light also stimulates melanin production, resulting in darker skin. The amount of melanin varies throughout the body - it is most concentrated on freckles, moles and less is found on the palms of our hands and soles of our feet.

Haemoglobin

This is a red pigment running along blood vessels. This results in skin being redder in places where the blood vessels come closer to the surface - eg lips.

Carotene

This is a yellow colour found in yellow and orange vegetables. If you have too many carrots, cantaloupes, or other yellow or orange vegetables in your diet, excess amounts can result in accumulation in the skin. The skin may also show abnormal colours such as:

Cyanosis: Blue colour in our skin, due to low amounts of oxygen in the blood. This can occur when we are cold.

Erythema: Increased redness in the skin, due to increased blood flow in blood vessels. This occurs normally when we are exercising or hot.

Jaundice: This is when our skin turns a yellow colour, due to increased bilirubin (a breakdown product of haemoglobin).

Pallor: When we loose our skin colour, due to decreased blood flow.

Albinism: Lack of melanin pigment in the skin, resulting in white hair, pale skin and pink eyes.

Reference

Kumar P, Clark M. Clinical Medicine United Kingdom: WB Saunders; 2002.
Human Skin Colour. (2006). [Online], Available from: http://en.wikipedia.org/wiki/Skin_color#References [1 March 2006].
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Slominiski A, Tobin DJ, Shibahara S. et al. 'Melanin Pigmentation in Mammalian Skin and It's Hormonal Regulation', Phyiol. Rev. Vol 84, No. 4, pp 1155-1228. 2004.
Saladin K S, Miller L. Anatomy & Physiology. USA; McGraw Hill; 2004.
Revis DR, Seagle MB. Skin Anatomy. E-medicine [serial online] 2006 [cited 2006 March 7] Available from: URL: http://www.emedicine.com/plastic/topic389.htm