Big Site of Amazing Facts; What Gives Your Skin Its Colour?
http://www.bigsiteofamazingfacts.com/what-gives-your-skin-its-color
Costin, G. & Hearing, V. 2007. Human skin pigmentation: melanocytes modulate skin color in response to stress. The FASEB Journal. 21: 976-994.
Jablonski, N. 2004. The evolution of human skin and skin color. Annual Review of Anthropology. 33:585-623
Jablonski, N. & Chaplin, B. 2000. The evolution of human skin coloration. Journal of Human Evolution. 39: 57-106.
Kids Health; Your Skin
http://kidshealth.org/kid/htbw/skin.html#
Medical News Today; What is Vitamin D?
http://www.medicalnewstoday.com/articles/161618.php
News Medical; Melanin- What is Melanin?
http://www.news-medical.net/health/Melanin-What-is-Melanin.aspx
Relethford, J.H. 2002. Apportionment of global human genetic diversity based on craneometrics and skin color. Am. J. Phys. Anthropol. 118, 393−398.
Smithsonian National Museum of Natural History; Skin Colour
http://humanorigins.si.edu/evidence/genetics/skin-color/modern-human-diversity-skin-color
Monday, 1 April 2013
UV Radiation: Pros & Cons
Vitamin D Synthesis: exposure to UVB initiates vitamin D synthesis. Vitamin D is a fat-soluble steroid that is necessary for calcium and phosphorus absorption. It is synthesized in adequate amounts by exposure to sunlight, so taking dietary pills is not necessary. It is also an immune regulator, and has been shown to reduce the risks of rheumatoid arthritis in women.
Medical Use: ultraviolet radiation is used to help treat psoriasis. This treatment helps clear the disorder, however it greatly increases the risk of skin cancer.
Skin Cancer: overexposure to UVB causes sunburns, but also skin cancer. UVC rays are the most dangerous type of ultraviolet light because they are the highest in energy. UVA, UVB, and UVC all directly damage DNA, so protection from all three forms is necessary.
UV radiation walks a thin line between being a benefit and a harm to humans. It is necessary for vitamin D synthesis, however it can be lethal by causing different forms of cancers. Without vitamin D, we can not absorb calcium which is crucial for our bones. However, spending too much time in the sun unprotected can result in cancer.
Medical Use: ultraviolet radiation is used to help treat psoriasis. This treatment helps clear the disorder, however it greatly increases the risk of skin cancer.
Skin Cancer: overexposure to UVB causes sunburns, but also skin cancer. UVC rays are the most dangerous type of ultraviolet light because they are the highest in energy. UVA, UVB, and UVC all directly damage DNA, so protection from all three forms is necessary.
UV radiation walks a thin line between being a benefit and a harm to humans. It is necessary for vitamin D synthesis, however it can be lethal by causing different forms of cancers. Without vitamin D, we can not absorb calcium which is crucial for our bones. However, spending too much time in the sun unprotected can result in cancer.
What Gives Skin Its Colour?
Melanin is responsible for giving skin its colour. The majority of skin cells are busy replacing the epidermis, but approximately 5% are making the brown/yellow pigment melanin. It is produced by melanocytes in the epidermis. The amount of pigment you have in your skin depends on the amount your parents had. Pigments get passed on from generation to generation. People with darker skin express the melanin-producing genes more frequently than lighter-skinned people.
Albinism is defined by having little or no melanin in the body. People that suffer from this condition have extremely pale skin, light hair and eyes. Melanin effects the colour of hair and the iris of the eyes, so they are affected as well.
When you go out into the sun, more melanin cells are produced to help protect the body from harsh UV rays. As more and more melanin is expressed, the skin becomes darker. That is why skin gets darker as you spend more time in the sun. The tan fades because new skin cells are produced which haven't been as exposed to the sun.
Albinism is defined by having little or no melanin in the body. People that suffer from this condition have extremely pale skin, light hair and eyes. Melanin effects the colour of hair and the iris of the eyes, so they are affected as well.
When you go out into the sun, more melanin cells are produced to help protect the body from harsh UV rays. As more and more melanin is expressed, the skin becomes darker. That is why skin gets darker as you spend more time in the sun. The tan fades because new skin cells are produced which haven't been as exposed to the sun.
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