Clinical Death

[chxn9]

Does anyone know what clinical death is?
How does it work and how is it even possible????
Do the people that undergo clinical death REALLY DIE and come back to life again????

[infamous]

Originally Posted by chxn9

Does anyone know what clinical death is?
How does it work and how is it even possible????
Do the people that undergo clinical death REALLY DIE and come back to life again????

Death is understood as the passing of life, to understand death, we must first understand what it means to be alive. For one to be inanimate is easy to understand, what is more difficult to reconcile is our consciousness in action. I believe your referring here to the Near death experience, which spells out by defintion, not yet dead. I'm not sure if science knows exactly when absolute death occurs because the question remains; What is consciousness and how far reaching is it's limit?

[MortenS]

As I deal with death in my line of work sometimes, I might answer this question for you.

As to the first question: What does it mean to be clinically dead.

You are clinically dead when the heart and respiration stops. All hope is not out, because in a certain timeframe after cardiac arrest, it is in many cases possible to jumpstart the heart again, and get respiration going by applying first-aid. Even if the first aid does not succeed in getting the heart and respiration started again, it may give the patient enough oxygen so that the brain does not die, and more advanced methods of starting the heart can be applied.

Also, cold temperatures slows the time it takes for cells to die, so people that drown in cold water often can be revived for a longer time period than those that drown in warmer water. Persons with low body mass cool quicker than persons with high body mass, and this is one of the reasons why kids have a greater chance of being revived after drowning and being submerged for a long time in cold water than adults.

It may help to understand the various versions of being dead by understanding that death is not an event, but a process.

If we take the case of cardiac arrest, the first thing that happens after the heart stops to beat, is that blood is no longer pumped through the body. Cells still have oxygen present that they can use, and the blood bathing the cells will also contain some oxygen. This oxygen gets rapidly depleted, and cells starts to work anaerobically. Some cells are specialized in working under anaerobic conditions, such as the muscle cells. It takes a long time before a muscle cell die because of that. Other cells, such as brain cells, do not deal very well with anoxia, and because of this, brain cells die after just a few minutes without oxygen supply. Cold temperature may increase the time it takes for the brain cells to die, because chemical reactions occur slower rates at lower temperatures.

This is the first part of death, and it happens during the first 5 minutes after cardiac arrest (may be longer in cold water). Everything but the brain damage is reversible during this stage. And even with some brain damage, it is possible to train other undamaged parts of the brain to do some of the functions that the old damaged parts did before. But in general, the longer it takes before basic first aid is applied, the greater the chance of permanent brain damage or even unsuccessful revival.

when all the parts of the brain, including the brain-stem, are non-functional, the person goes from clinically dead to irreversibly dead. Even at this point, many other cells in the body is still alive. One of the longest lived cell types are those of the cornea, as these get oxygen from the air, not from blood. I can probably give a long speech about the later changes after death, but I think I will stop here.

[pgrmdave]

That was wonderfully informative, Morten, thank you. I had been wondering about this for a while, what makes us dead, especially when many of our cells can be 'alive'. Thank you for explaining it.

[MortenS]

You are welcome. A rather good book on this topic is "How we die - Reflections on Lifes final chapter" by Sherman B. Nuland. I reccommend it to everyone that are not going to live forever.

[alexander]

I reccommend it to everyone that are not going to live forever.

Phew, and I thought I needed to read that...

[MortenS]

Originally Posted by alexander

Phew, and I thought I needed to read that...

You do not have to, but I did write a piece on death on my website many years ago at
http://folk.uio.no/mostarke/forens_ent/afterdeath.shtml that you might want to read that in addition to what I wrote above. The webpages are not for the squemish though.

[chatlack]

I wonder what cell death is.
what makes cell live? Can it live again? How can god create these with "life" in it?

I think these can be solved soon.... But any answer now??

[MortenS]

What makes cells live? Good question...

Anyway, here is my account of cell death by autolysis (it is largely from a book called: Forensic taphonomy: the postmortem fate of human remains.)
There is a controlled form of cell death that is called apoptosis. I will not cover that mode of cell death here.

As we all know, cells require energy to function. This energy is harnessed from covalent bonds in carbohydrates and converted to the energy carrier ATP in mitochondria (in the process of oxidative phosphorylation).

Oxygen is required to drive the process of ATP-formation.

Anoxia will therefore drastically reduce ATP-formation
ATP-driven biosynthesis of important molecules (enzymes, lipids, carbohydrates etc) will fail.
Membran-bound enzyme systems will fail
Failing of membrane pumps leads to osmotic imbalance and flooding of the cell -> swelling
Shift to anaerobic pathways for ATP production. This creates lactic acid. Fermentation of lactic acid cause lower pH in the cell.
Increased acidity cause nuclear cromatin to clump, supressing RNA formation, and further reducing protein synthesis, including enzymes.

So far the process is reversible, if oxygen is provided, the cell will be able to repair itself.

The following process is irreversible:
Matrix proteins of the mitochondria get denatured
Proteins in the cytoplasm gets denatured
Increased permeability of all organelles with membranes leads to leakage from the organelles
Hydrolytic enzymes from damaged lysosomes gets activated at low pH (remember the lactic acid)
These hydrolytic enzymes leak into the nucleus, and irreversibly degrades chromatin, and eventually all other structures in the cell.
As the cell membrane gets destroyed, the hydrolytic enzymes will leak out in intercellular space, and will cause loss of cell-to-cell attachment.

Macroscopically this is noted on the skin of a dead person as necrosis and skin slippage.

[chatlack]

Thanks but I wonder how can it live again... Is death physical???? I say can we freeze everything in a cell to prevent physical dying procces??

But death seems more than physical. Dont get my wrong, I say death is like a social event between organels in it.