| MadSci Network: Anatomy |
Dear Nikko,
Let me start with a 'physical' definition of 'melt'
melt: to make into or become liquid by heat. (Oxford American Dictionary)By this definition skin does not melt. When you apply heat to a solid 'meltable substance' such as ice the water molecules abosorb the heat. After applying a certain amount of heat the ice 'melts.' The energy transferred as heat causes the water molecules to vibrate, to the point where they can no longer remain in the solid state. Adding further energy to the now liquid water continues to increases the molecules' vibrations. With sufficient energy they break away from one another to form a gas - steam.
While water consists entirely of molecules of H2O, skin is made of many different compounds, including water, proteins such as keratin and collagen, and elements found in fatty tissue and blood vessels. Adding heat to skin increases the vibration of molecules in the skin. Rather than melt a number of things can happen. Heat can denature proteins, causing them to become inactive and form solid clumps of material. It can also ignite materials in your skin causing direct burns.
Recent sensational stories in the news media about 'flesh eating bacteria' mention cases of microbes 'melting' flesh. However, this interpretation is far from true (skin can't melt.. right?), and is more than often a great overstatement of what really happens. The disease in question is called necrotizing fascitis. Some virulent strains of bacteria produce potent toxins that kill skin cells. If the microbes colonize a wound or other infected site they can cause serious damage. The disease is rare in the US, particularly in healthy epople ( 500 -1000 cases per year).The infected area produces a lot of pus, fluid and dead skin that sloughs from the site, perhaps giving an impression of melting flesh.
-N.B.
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