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What is Death?

  1. Jul 15, 2004 #1
    A person is alive, animated, breathing, communicating, thinking, moving. There is brain activity - an energy which can monitored by a machine. Then suddenly their body is a cold lifeless shell and no brain activity can be found.

    In the terms of physics - what has happened?

    Where did that energy registering as brain activity go? Does it still remain dormant within the body? Did it go some place else? Where? How?
  2. jcsd
  3. Jul 16, 2004 #2
    "Death is either an eternal sleep, or a travel to another space/dimension" - Socrates.

    If you believe in the soul, then when someone dies, his soul leaves his body. On the other hand, death can occur when the body cannot support itslef anymore, thus it stops functioning.
  4. Jul 16, 2004 #3


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    In terms of physics, you could say broadly that death is the occurence of monotonically increasing entropy within the organism. Life requires a great deal of structure and organization, and the cessation of such organized processes in a living organism is basically synonymous with the cessation of life itself.

    Brain activity is the result of the dynamic flow of ions into and out of neurons, which creates a moving electric charge along the length of the neuron. So brain activity is essentially driven by a chemical process. Without the proper conditions in the body, such as a sufficient level of body heat and circulation of blood, these driving chemical processes cannot continue to function, and so coordinated electrical flow through the neurons ceases.
  5. Jul 16, 2004 #4


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    Medically speaking, death is defined as the irreversible ceasing of both heart and brain activity. A person can be brain-dead (all thinking and voluntary motor functions have turned off) and still be considered alive, although the living body still in function would probably not be considered a person.

    Not all brain activity produces an electric current, either. Intraneuronal processes, as well as exchanges of non-charged neurotransmitters that are not regulated by calcium ion channels result in no change of membrane voltage.
  6. Jul 17, 2004 #5


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    One strange thing about death is that the individual organs and tissues remain alive much longer than the body as a whole. Once brain and heart activity cease, organ systems are no longer coordinated, and oxygen and nutrients are no longer pumped out to the organs, so death of the remaining tissues follows relatively soon after the heart stops pumping, though not at all immediately. This can be used to advantage in medicine, where a heart-lung machine can be used to artificially maintain circulation through the body of a deceased person in order to keep the organs viable long enough for a transplantation team to arrive and harvest those organs to save the lives of other people.

    So, I guess one way to define death would be when all the organ systems of the body cease to function in a coordinated manner and homeostasis cannot be maintained. That seems to address the problem of individual organs, tissues and cells remaining alive longer than the organism as a whole. Though, I can find problems with this as well. Someone who is a quadriplegic following a spinal cord injury isn't considered dead, even though their organ systems do not act in a coordinated manner and they may have difficulty maintaining homeostatic mechanisms in their body without mechanical assistance.
  7. Jul 17, 2004 #6

    Ivan Seeking

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    Death is precisely that state in which you are not longer liable for taxes.

    Hypnagogue, you may remember my question about "deep" brain wave activity. Does this relate to limbic activity rather than cognitive processes? If so, how do we acquire complex memories when surface activity ceases?

    A friend of mine once described his experience when given an anesthetic for surgery. He noticed that as with Alzheimer’s disease, many levels of the self seem to exist that may or may not be active or “alive”. His feeling was that when first given a pre-surgical shot, he lost a part of himself to unconsciousness. As he was given the general in surgery, he felt more and more of his mind going, one piece at a time.

    So I guess this raises the question: Can part of us die while the rest remains in tact? Is death a sequence of events with no clear boundary, or is there a unique self that dies as the ultimate death? What if two brain cells are active? Three? Three million? When exactly are we no longer "in there"?
  8. Aug 3, 2004 #7
    Our central, peripheral, and autonomic nervous systems are approached individually in modern medicine. Your friend could only "know" he was about to become unconscious. If you ask a patient what the last thing they remembered was, a descent of sorts is the common answer. Horror stories abound of people being conscious during surgery though unable to move or scream out. Some people are less sensitive to CNS drugs and wake up, paralized.

    The myriad of theory regarding existance, consciousness and death is exhausting. It is the worm at the core.
    Consciousness is a function of survival. Everything we are is sensory. If I don't "know" I exist after death, I do not.
    The energy that animates my frame existed before I was conceived. Did I exist then ? There's no comfort in knowing my kinetic energy will go on to become some other atomic aggregation.There's a grief for the self that's seperate from our fear of dying.
    Last edited: Aug 3, 2004
  9. Aug 8, 2004 #8
    You die in stages. At least that is my experience. You lose the ability to see before you lose hearing. I have heard this from others as well which I take as confirmation.

    I remember the anxiety in the anasthesiologists voice as he was directing his nurse assistant. I was blind -- and aware. Couldn't breathe. Terrible thing to know you are on the edge and sliding.

    I am changed as a result. I never cared for love stories for example. Always liked those mindless "action" movies and "clever" dialogue. Now Don Quixote (O'Toole) or Don Juan de Marco (Brando and J Depp)move me to tears. Or
    Second Hand Lions, the speech by the pond --again, profound and moving.

    I regret that I have not brought more joy into the world.

    I wonder what people I knew long ago are doing. Are they happy- are they well. I mean even people I haven't thought of once in 25 or more years. Now they are on my heart. I feel concern. I wish I could find them.

    I see the world differently.
    It is a bit overwhelming.
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