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When is dead really dead? | Human world



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  A live pink baby pig.

A recent study of the brains of decapitated pigs showed activity in their brains four hours later. Picture about Ivan Loran / Shutterstock.com.

By Katharina Busl, University of Florida

"Death" was the longest time when the heart stopped beating and breathing ceased. Then, in the 1930s, machines were invented that made it possible for people to receive air, even if they could not take in the air themselves. In the fifties, machines were developed to support the heartbeat.

But no machine could bring an irreversibly brain-damaged patient to a functioning brain. Therefore, the concept of "brain death" has been introduced as an additional definition of death to supplement death from cardiopulmonary failure.

The concept of brain death, which was introduced legally in the US and much of the world, has remained an area of ​​ongoing discussion. Often it is about how someone can be dead, when the heart is beating and the body is warm, even if this function is completely achieved through artificial support. Brain death is also harder to understand because it is a less visible form of death. And is not it so much easier to believe what we can see?

On April 17, 2019, a study published in Nature showed signs of activity in swine brains after being killed, and added more fuel for discussion. I am a neurologist specializing in neurocritical care with both clinical and research interests in acute brain damage and broad exposure to catastrophic brain damage and brain death. My analysis of the study is that it supports much of what we already know, that death is a continuum.

When pigs die, can their brains be revived?

The Study Involved Scientists Brains of pigs slaughtered at USDA-regulated facilities were connected to a machine that pumped artificial, blood-like nutrient fluid through the brain four hours after their "death." Measured activity of brain cells. They found that even hours after death, blood flow or blood flow to the artificial blood and certain brain cell functions could be restored in this experimental setting.

The conclusion was that after the heart stops beating, the demise in the brain follows a longer process and does not occur at any given time, and our brain may have better healing capacity than is currently known.

This news? Yes, on a scientific level – under the microscope, because an experiment like this has not yet been done. Did not we know for a long time that death does not happen in the blink of an eye?

Historical reports of decapitated bodies taking a few steps or even running.

  Two surprised men, seeing a boy with his neck cut off and holding his own head at chest height with big eyes.

A painting by Sir Peter Paul Rubens illustrates the story of the nine-year-old martyr Justus, who is said to have held his head in his hands after being beheaded. Picture via Wikipedia.

This means that such a body was not dead immediately. And if you provide such a body with blood and heal the wounds, most people could probably imagine that they could continue to be supplied with living body parts or cells.

Can a head still be alive after decapitation?

Worse to think: Could the decapitated head still be aware a bit? Maybe yes.

After the heart stops beating, we think someone has died. But after the heartbeat stops, we also know that sometimes the heartbeat can come back by itself. This is called automatic resuscitation. In this case, someone who died for a few minutes did not really die.

But the situation is different for the brain than for the heart. If there is no blood flow in the absence of a heart that pumps it, or if there is an intrinsic brain injury and blood can not enter, the situation is difficult. Brains are very sensitive to oxygen and energy, and various brain injuries occur. Depending on how long the energy source is not available to the brain, brain function can be maintained to varying degrees and revived to a degree that we neuroscientists are not fully aware of. We know that brain function is seriously disturbed, with loss of function variable depending on how long the brain has lost energy.

The end result of how functionally such a damaged brain will emerge is one of the biggest challenges we have to learn more.

Following an injury, a whole series of sequential processes known as secondary brain injury are triggered primarily by brain damage. And these processes often cause enormous damage and sometimes more than the actual first injury.

For example, a hard blow to the head can lead to bruising or bleeding in the brain, which in certain cases can be surgically removed. Although the bleeding is stopped or removed, the surrounding brain swells even more in the following days, just as a large bruise on the thigh undergoes stadiums and color changes. There is no preventative therapy yet, but we know that some factors can exacerbate this process, such as low blood pressure or lack of oxygen for the brain during the healing phase.

Imagine a broken bone: occupation is only the first step, and weeks later there are swelling, pain and weakness. In the brain, the process is more granular. And in neuroscience, we are just beginning to understand this cascade of events.

What to Learn from the Pig Study

The study of revived pig brain cells is not nearly touching this much larger picture. It can only be shown that the time span and the spectrum of nerve cell function that can persist and at least partially recover is longer than previously shown. Therefore, it supports the idea that dying is a process and provides additional information about the length of this process.

However, it does not appear that these brain cells could function as a neural network that leads to higher brain function such as consciousness or consciousness – the traits that characterize us as humans. It's all about the immediate restoration of cell function, not how these brains come together when the ongoing processes of secondary brain damage set in.

In summary, the brain, including the blood flow, gathers together All of its individual cells will eventually die. And this study may have broadened the understanding of "sometime".

Death is a process and not a moment in time. It is the human desire to bring things into categories of black and white and to have definitions that allow us to operate in everyday life. Death – it is becoming clearer and clearer – is a big gray area, and we will have to expect this gray area to grow with the advancement of science.

Katharina Busl, associate professor of neurology. Chief, Department of Neurocritical Care, Department of Neurology, University of Florida

This article was published under [Creative Commons License] The Conversation . Read the original article. Conclusion: A recent study on the brain of pigs suggests that some activities could be restored even after they were dead for four hours, reinforcing the idea that death is a continuum.

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