Question: how is it possible to be stilll fully functioning (like our organs) even if we are unconcious? also how do life support machines work?

Damien Hall answered on 20 Jun 2011:

It’s possible because the brain is what makes those organs work, and the brain is never completely switched off. When you’re asleep or unconscious, your brain does work a bit differently from when you’re awake (I think you could say that’s why being asleep is different from being awake – because the brain’s doing different stuff), but it’s still working. You can tell it is because your organs still work (and also because you dream, for example, when you’re asleep).

This is why I think there are two competing definitions of ‘death’ (ways to say when a body has died): one has to do with heart damage that can’t be repaired, the other has to do with brain death. If your heart is irreparably damaged, it can’t pump blood around the body any more, and so you die; if your brain is dead, it isn’t telling the body to do anything any more, and so it dies as the blood stops pumping and so on. While you’re only unconscious or asleep, your brain hasn’t stopped telling your body to do the things keeping it alive, and so you are still fully functioning.

Life-support machines are really beyond what I know about, but, as far as I can see from a bit of research, the phrase is actually an overall name for any machine that’s keeping someone alive, no matter what it is that’s wrong with them. So you could call a heart-lung machine a life-support machine, or a machine that breathes for you, and so on. In other words, how a life-support machine works depends on what it’s doing for the patient on life-support! Some breathe, some pump blood, some do both, some do other things, etc etc. There’s a little bit more information here:

http://en.wikipedia.org/wiki/Life_support