What decides death?

[BioNerd]

When in my biology classes, we always talk about what would happen if XYZ happened - and often times it's either something catastrophic to the animal/cell or it causes death. But this has me wondering - what decides death? How do you decipher between a plant that is alive or dead? Does death happen at the cellular - or even subcellular level? Or does it have to involve the break-down of tissues and organs? I know an animal can be considered dead even if the heart is still beating, but then how do you know it is dead? And with plants - if you cut a flower, is it considered dead? If it is mostly wilted but part of it is still green and turgid, is it still considered living in some respects?

[rakuenso]

Wow if we knew what decided death we would've found a cure already. Obviously that isn't the case. Take the example of viruses, are they dead or alive, nobody knows. For multicellular organisms, a dead organism is an organism that no longer affects the population.

[smommer]

For multicellular organisms, a dead organism is an organism that no longer affects the population.

 

what about people who suffer from locked in syndrome, who have absolutely no way of communicating with the outside world?

 

i know work has been done with brain body interfaces that allows limited interaction but this is still fairly recent

[cpwmatthews]

I wounder if the brain effects death? does it somehow judge the decaying body and then switch it off?

[imasmartgirl]

I wounder if the brain effects death? does it somehow judge the decaying body and then switch it off?

 

i would think that the lack of oxygen and blood to the brain would give it a good indication to shut down

[Xyph]

The brain would be the last part to go, I expect, since it's the most vital organ (if it is in fact classed as such) and is in control of the rest, so it would make sense for it to keep itself alive as long as possible.

[BioNerd]

The brain would be the last part to go, I expect, since it's the most vital organ...

 

Actually, in that case, I would believe the heart to be the most "vital" organ because without it, the brain is nothing. The heart can beat after the brain ceases functioning, and often times the heart will continue to beat even after the animal is considered dead. Similarly, the heart can continue to beat after being extracted from the body. The muscle cells of the heart control their own ability to pulsate, and the only intervention the brain has is whether the pulse should speed-up or slow-down.

[Glider]

True, but the heart is autonomous. The brain is the most vital organ. The evidence for this is the lengths a body will go to in order to preserve the brain.

[RyanJ]

I thgink natural death actually comes down you your genes. Your sels can only coppy themselves xxx number of times before they die, after that they are never replaced. The process is quite slow but as time progresses and you loose more and mlore then it becomes noticable...

 

How about that?

 

Cheers,

 

Ryan Jones

[Danecookie]

True, but the heart is autonomous. The brain is the most vital organ. The evidence for this is the lengths a body will go to in order to preserve the brain.

 

yea, brain is the main control system...

[Sisyphus]

The fact that cells only copy themselves a certain number of times is why we age, and its why death is inevitable with time, since sooner or later something vital is going to stop functioning and not be repaired. What actually defines death, though, is (I believe) just the destruction of the brain, which is caused in almost every case by lack of oxygen. For example, the weakened heart stops, blood stops circulating, the brain stops getting oxygen, and it dies within a few minutes.

[sunspot]

Neurons use a lot of oxygen and can not function for long under anaerobic conditions. The single brain cells may still show some anaerobic biology but the overall brain mechansim is without the needed energy. Without the coordinated firing of neurons there is no consciousness or life.

[Kedas]

A plant doesn't have a brain so it can't die because the brain doesn't get enough oxygen....

[RyanJ]

A plant doesn't have a brain so it can't die because the brain doesn't get enough oxygen....

 

No, it dies because all of its cells have reached their cellular division limit.

or because someone stamped on it or cut it down or lack of nutrients and sunlight...

 

 

Cheers,

 

Ryan Jones