Melanin

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Melanin is the pigment found in skin, hair and the iris of the eye. [1]It provides these with colour. It has two main functions: to provide colour in these organs and to protect them from UV light [2].

The pigment is produced in melanocytes on exposure to UV rays from sunlight, causing the skin to tan in order to protect the skin from damage. Melanocytes are found between the dermis and the epidermis in skin. The more active they are, the more pigment will be made and the darker the skin will appear. [3] Mammals usually have a mixture of both types of melanin [4]

There are three types of melanin: eumelanin, phaeomelanin and neuromelanin.The first causes brown colours and the most known, the second is responsible for reddish colours and neuromelanin is found in the parts of the brain.  [5]

Skin pigmentation as well as epidermal thickness, DNA repair mechanisms, apoptosis and some other factors prevents DNA damage from ultraviolet light. UV radiation’s destruction of DNA is one of the major factors causing skin tumours like basal cell carcinoma (BCC), squamous cell carcinoma (SCC) and malignant melanoma. [6]

References:

  1. https://www.nlm.nih.gov/medlineplus/ency/article/002256.htm
  2. PubMed Health. 'Melanin - National Library Of Medicine - Pubmed Health'. N.p., 2015. Web. 19 Oct. 2015. http://www.ncbi.nlm.nih.gov/pubmedhealth/PMHT0022690/
  3. http://www.cancerresearchuk.org/about-cancer/type/melanoma/about/the-skin-and-melanoma
  4. Hearing, Vincent J., and Katsuhiko Tsukamoto. ‘Enzymatic control of Pigmentation in Mammals’. FASEB J. 5 (1991): 2902-2909. Web.19 Oct. 2015. http://www.fasebj.org/content/5/14/2902.full.pdf
  5. http://palaeo.gly.bris.ac.uk/melanosomes/melanin.html
  6. Brenner, Michaela, and Vincent J. Hearing. 'The Protective Role Of Melanin Against UV Damage In Human Skin'. Photochemistry and Photobiology 84.3 (2007): 539-549. Web. 19 Oct. 2015.http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2671032/

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