Few stupid questions about death?

[scilearner]

Hello everyone,

 

These might be stupid but I'll ask anyway. Ok let's say a person died because a major artery supplying the brain was damaged. After a while if someone fixes the artery and supply some blood, would the person come alive again. What basically I'm asking is if someone died to reversible damage like this, if you fix it soon can he come back alive. Ok why doe many people die due to brain damage, if they are still breathing and the heart is pumping aren't they still living?How can damage to the brain affect breathing or pumping of heart? So if you fix their brain damage would they come back alive. Also why is their no pulse after you die, if the heart is autopacemaker and is still beating. Thanks

[Sisyphus]

Hello everyone,

 

These might be stupid but I'll ask anyway. Ok let's say a person died because a major artery supplying the brain was damaged. After a while if someone fixes the artery and supply some blood, would the person come alive again. What basically I'm asking is if someone died to reversible damage like this, if you fix it soon can he come back alive.

 

Not if "after a while" is more than a few minutes. The thing about the human body, and especially about the brain, is that it needs to be constantly supplied with oxygen in order to keep from being destroyed. It's not like a car engine that you can turn off and on again. It's more like juggling eggs. Stop moving your hands, and the eggs fall and break. Stop supplying the brain with oxygen, and the damage starts almost immediately, and is irreversible.

 

Ok why doe many people die due to brain damage, if they are still breathing and the heart is pumping aren't they still living?

 

That's just how we define death. It makes sense, since without a functioning brain, you're basically just a bag of meat.

 

How can damage to the brain affect breathing or pumping of heart?

 

The brain pretty much controls everything in your body.

 

So if you fix their brain damage would they come back alive.

 

Sure. But fixing that kind of brain damage is way, way beyond anything we are capable of.

 

Also why is their no pulse after you die, if the heart is autopacemaker and is still beating. Thanks

 

If the heart is beating, there is a pulse.

[ewmon]

No question is stupid. Basically, brain cells are highly specialized and do not store much energy, so they meet their immediate energy from the bloodstream. On the other hand, muscles has greater stores of energy and can “survive” several hours without a blood supply (ie, by amputation or tourniquet, including “falling asleep” due to a compromised blood supply). Brain cells cannot do that, and the commonly understood limit for brain cell “survival” without a blood supply is 4 minutes. Pretty much, once any cell dies, it’s dead, and there’s no way to “jump start” it back to life.

 

As to reversing damage, yes, people do “come back to life”, so to speak, but their brains never really “died” — but were only dying or compromised. Researchers now work with some exciting developments on how to treat the dead. They found that too much oxygen too quickly can cause damage or death, and that slow reperfusion over time allows the cells to “wake up” more safely (kinda like turning your computer on in “safe” mode).

 

A “brain dead” person has little/no brain function but the heart and lungs continue to function. People also call this a “vegetative state” or, less respectfully, they call the person a “vegetable”. These words come from the Latin vegere, meaning “alive”. Compare this to “animal” (as in the first question in 20 Questions: “Animal, vegetable or mineral?”), which comes from the Latin anima, which means “soul, mind, spirit etc”. So, the use of “vegetative” makes sense — the “person” (ie, the person’s body) continues to live, but the soul/mind/spirit is gone.

 

Sometimes the heart and lungs continue to function without signals from the brain because the heart has its own pulse generator in its SA node, and because the celiac plexus (aka “solar plexus”, a network of nerves) in the abdomen just below the diaphragm controls the lungs. “Getting the wind knocked out of you” occurs when this respiratory circuitry malfunctions due to abdominal trauma (ie, a punch to the “stomach” or falling on your back.

Edited June 3, 2010 by ewmon
Consecutive posts merged.

[Mr Skeptic]

You seem to be coming from the perspective that the body is the large scale pieces and organs. We are made of about a trillion individual cells which can individually live or die. Cells need oxygen to live, and so depriving them of oxygen will kill them. The brain in particular needs a constant supply of oxygen and will die in minutes without it.

 

However, there is somewhat of an exception. If a body is very cold, the processes of the cell slow down significantly, and so too do the oxygen requirements. This is why people who "drowned" in cold water can sometimes be revived 30 or so minutes later which would be deadly for someone who was still warm. They say that you're not dead until you're warm and dead.

[scilearner]

Thanks for all the answers They were all very helpful. Ok if the cell don't gain energy, can't that part of the brain shut down temporarily without dying, what I mean is can't the brain make you unconscious and cut down all your activity until someone fixes it. I think when I think of energy I only think of cellular respiration, if cellular respiration stops I can understand how all the metabolic activity would stop but why would structure of the cell break down. Thanks

 

EDIT: Do you need ATP to sustain the phospholipid bilayer of cells?

Edited June 4, 2010 by scilearner

[Double K]

Thanks for all the answers They were all very helpful. Ok if the cell don't gain energy, can't that part of the brain shut down temporarily without dying, what I mean is can't the brain make you unconscious and cut down all your activity until someone fixes it. I think when I think of energy I only think of cellular respiration, if cellular respiration stops I can understand how all the metabolic activity would stop but why would structure of the cell break down. Thanks

 

The body does actually always try to maintain a thing called

homeostasis

 

So it will actually try at all times to maintain equilibrium.

Hence why if you have low blood pressure you may pass out.

Baro-receptors in your neck near your jugular veins constantly monitor blood pressure.

This is the bodies way of returning pressure to normal by making it so your heart isn't pumping blood uphill to your brain.

 

Also certain functions may stop (such as consciousness) however some functions are involuntary (such as your heart beating)

this is controlled by the autonomic nervous system

 

But in certain cases merely trying to maintain homestasis isn't enough, there may be a structural blockage, or a rupture, and your body simply doesn't have mechanisms to deal with certain critical failures.

[scilearner]

Thanks DoubleK. However I don't understand why neurons need to be continuously supplied with ATP. Is it because they need ATP to open protein channel to carry out action potential, or is the extra cellular matrix of a neurone determined by the blood supply. If a neurone can not carry out cellular respiration, why would it cause permanent damage to the structure?

 

EDIT: Without ATP you want have the proper concentration of solutes inside the cell, so the cell can swell and burst. Is that what happens?

Edited June 4, 2010 by scilearner

[ewmon]

I don’t pretend to understand all of this. There seems to be a chemical “point of no return” after which the neurons cannot recover, and it involves the intracellular (ie, within the cells) accumulation of free calcium. Calcium is an electrolyte (it’s not just for bones and teeth), so talk about depolarization seems to refer to activities involving calcium.

 

We distinguished three main phases of cerebral hypoxia. First, withdrawal of oxygen is rapidly followed by failure of synaptic transmission. Second, there is massive depolarization of cells, resembling the “Spreading Depression of Leão” {a self-propagating wave of cellular depolarization in the cerebral cortex consisting of a wave of electrophysiological hyperactivity followed by a wave of inhibition}. Timely reoxygenation can still restore function. If, however, the depolarization continues beyond a critical time, the third phase, irreversible loss of responsiveness, sets in. Cell loss is initially highly selective. Finally, upon reoxygenation, some neurons, which at first appear normal, then undergo a sequence of changes leading to delayed neuron degeneration.

 

Hypoxic depolarization is a complex but stereotyped and explosive event. The longer the depolarization lasts, the smaller the chance for functional recovery after reoxygenation. The least likely to recover are those cells that undergo depolarization the earliest. Prolonged intracellular accumulation of free calcium, admitted into the cells by the membrane change, plays a key role in causing neuron damage.

 

Excerpt from: Cellular physiology of hypoxia of the mammalian central nervous system