Question: why do we burn?
Drew Rae answered on 13 Jun 2011:
There are a few different things that we call burns. Burns can come from chemicals, friction, radiation (including rays from the sun), electricity, and heat transfer.
Apart from chemical burns, all of these involve transferring more energy to our skin and the flesh underneath it than it can cope with. The skin gets damaged, and the cells may die. The redness is from extra blood-flow to try to deal with the damage.
Amy MacQueen answered on 13 Jun 2011:
I am sitting with a doctor and he says he doesn’t really know – apparently the actual in detail mechanism of sunburn is not very well understood (if thats the type of burning you mean). That’s a really good question – maybe you should try and find out. People with dark skin technically should burn less (except I have a friend who is darker than me – her Dad is from Mauritius – but she burns more than me….hmmm).
Anyway we get exposed to UV radiation in the sun and this can cause damage to our skin (sunburn) and skin cancer. UV radiation can cause breaks in our DNA and this is what makes us more cancer-prone. So, if you are out in the sun you should always wear sunscreen!! 🙂
Kimberley Bryon answered on 13 Jun 2011:
I am not sure whether you mean chemical burn, sunburn or burning from catching fire?
Chemical burns and sunburn have been explained really well by Drew and Amy so I am going to answer burn as in terms of catching fire. All organic material (including us humans) is made up of carbon, it this that means we can burn as when we catch fire, the bonds that hold the carbons atoms together get broken. Metal doesn’t have these carbon bonds so this is why it doesn’t burn but melt at high temperatures. Hope that this makes sense.
Julia Griffen answered on 13 Jun 2011:
We burn because our cells are delicate and can be damaged easily… we are delicate creatures!
Typically sun burn occurs due to exposure to harmful UV rays.
Melanin is the pigment that protects cells. Pale skins tends to burn more easily.
Sara Imari Walker answered on 13 Jun 2011:
Hi emccullagh784 and rmcaneney950! I am not sure what exactly what you mean by “burn” either, be it chemical, sunburn, or burning in a fire. I guess as scientists we tend to be pretty specific! I think all the answers here are just great. I like Kimberely’s explanation relating it back to carbon. Organic matter including humans is made of carbon as Kimberely described. Wood is organic and therefore made of carbon so it burns, making an excellent fuel source for our fireplaces.
Sunburns are a different story though. They are caused by UV radiation damage from the Sun. UV is particularly bad for our DNA (the really giant double helix molecule in all our cells that carries genetic information). DNA is very sensitive to UV, so cells on the surface of our skin are highly susceptible to DNA mutation and damage. The dry flaky skin we get from a sunburn is our body trying to get rid of these damaged cells. We do have some protection though. We produce a chemical called melanin in our skin which can absorb harmful UV light before it can damage the DNA in our skin cells. People with darker skin produce more melanin and therefore have a lower risk of sunburn. Our bodies do some amazing things!! However, prolonged sun exposure will be detrimental to anyone! So wear sunscreen!! =) I know I do when I am out in the sunny desert here in Arizona!