MadSci Network: General Biology

Re: Can the skin detects the presence of pure light?

Date: Wed Jul 21 08:32:53 1999
Posted By: Demian Bertozzi, Grad student, Physics, UFSC
Area of science: General Biology
ID: 925522514.Gb

Initially, thereís two ways to understand the question. Youíve mentioned
the darkening of skin when exposed to ultra-violet rays. It happens 
because light rays in ultra-violet range are more energetic than the other 
colors of visible light spectrum. The skin, when exposed to these rays, 
produces melanin, a substance that acts like a solar filter, protecting 
the skin from burning. Other frequency rays (the frequency determines 
the color of light) donít make the skin release melanin as the ultra-
violet does... BUT, by the Physics point of view, every atom (and so your 
skin cells) reacts to the light, which is made of photons. These photons 
interact with the electrons of the atoms in your cells, producing 
vibration on these atoms. Itís the molecular description of heat. If the 
light rays excite your atoms enough, your local nerves, and then your 
brain, will react and feel this heat. Thatís a kind of ďneurobiologicalĒ 

Hope this is useful


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