Why Does The Brain Need Oxygen
The brain represents just 2% of a person’s body weight, yet it uses about 20% of the body’s oxygen supply. Without it, the brain can’t perform even the most basic functions. The brain relies on glucose to power the neurons that control everything from conscious functions like planning and thought to automatic, unconscious processes like managing heart rate and digestion.
Without oxygen, the brain’s cells cannot metabolize glucose, and therefore cannot convert glucose into energy.
When your brain is deprived of oxygen, then, the ultimate cause of brain death is inadequate energy to power the brain’s cells.
Can A Head Still Be Alive After Decapitation
Even worse to imagine: Could the decapitated head still be conscious for a bit? Perhaps yes.
After the heart stops beating, we consider that someone has died. But, after the heartbeat stops, we also know that sometimes, the heartbeat can come back by itself. This is called autoresuscitation. In this case, someone that appeared dead for a few minutes may not have actually died.
But the situation is different for the brain than for the heart. When there is a lack of blood flow in the absence of a heart that pumps it, or when there is intrinsic brain injury and blood cannot get in, the situation is tricky. Brains are very sensitive to being deprived of oxygen and energy supply, and various degrees of brain injury occur. Depending on how long the energy fuel to the brain is absent, brain function can remain alive to various degrees and be rekindled to a degree we neuroscientists do not yet fully know. We know that brain function is seriously disturbed, with variable permanence of function loss depending on how long the brain has not had energy.
The end result of how functional such a damaged brain will come out is one of the biggest challenges we have to learn more about.
After an injury, a whole sequence of consecutive processes occurs that is called secondary brain injury and is triggered by the insult to the brain in the first place. And these processes often cause tremendous damage, and sometimes more than the actual first injury.
What Physically Happens To Your Body Right After Death
It is difficult to generalize how people will respond to the subject of death because each of us is unique, but we generally feel uncomfortable at the thought of our own mortality. What often underlies this uneasiness, however, is thinking about the process of dying and the fear of a prolonged or painful death, rather than the state of being dead.
Ironically, despite spending a lifetime walking around in the same body and doing our best to care for it, few seem to wonder what happens to their physical remains right after death occurs. Here is a timeline of the processes involved, assuming the deceased remains undisturbed, including the transition from primary flaccidity to secondary flaccidity.
Verywell / Brianna Gilmartin
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How Long Can The Brain Go Without Oxygen A Timeline
- Between 30-180 secondsof oxygen deprivation, you may lose consciousness.
- At the one-minute mark, brain cells begin dying.
- At three minutes, neurons suffer more extensive damage, and lasting brain damage becomes more likely.
- At five minutes, death becomes imminent.
- At 10 minutes, even if the brain remains alive, a coma and lasting brain damage are almost inevitable.
- At 15 minutes, survival becomes nearly impossible.
There are, of course, exceptions to every rule. Some training routines help the body make more efficient use of oxygen, enabling the brain to go longer periods without this vital element. Free divers routinely train to go long periods without oxygen, and the current record holder, Aleix Segura held his breath for 24 minutes and 3 seconds without sustaining brain damage!
Researchers Discover Some Brain Cells Increase Activity After Death
May 26, 2021 by QPS Neuropharmacology
Contrary to popular belief, the human body doesnt die immediately after the heart stops beating. The body is made up of a massive network of cells, some of which remain active after we die. In fact, recent research from the University of Illinois Chicago reveals that some cells brain cells, specifically might even increase their activity after death and grow at an astonishing rate. The implications of increased brain cell activity after death offer stunning possibilities for the neurological community as a whole.
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Hearing Persists At End Of Life
- University of British Columbia
- Hearing is widely thought to be the last sense to go in the dying process. Now, the first study to investigate hearing in palliative care patients who are close to death provides evidence that some may still be able to hear while in an unresponsive state. Electroencephalography was used to measure the dying brain’s response to sound. The findings may help family and friends bring comfort to a person in their final moments.
Hearing is widely thought to be the last sense to go in the dying process. Now UBC researchers have evidence that some people may still be able to hear while in an unresponsive state at the end of their life.
This research, published recently in Scientific Reports, is the first to investigate hearing in humans when they are close to death.
Using electroencephalography , which measures electrical activity in the brain, the researchers analyzed data collected from healthy control participants, from hospice patients when they were conscious, and from the same hospice patients when they became unresponsive. The patients were receiving palliative care at St. John Hospice in Vancouver.
This new insight into the dying brain’s response to sound can help family and friends bring comfort to a person in their final moments.
Blundon says what while the evidence of brain activity supports the idea that a dying person might be hearing, they can’t confirm whether people are aware of what they’re hearing.
Anne Boleyn: Drama Queen
Other studies have shown activity in the brain 30 minutes after the heart has stopped beating. These so-called delta brain waves are also often seen in stages of sleep and relaxation.
Final wave goodbye
Most recently, research has shown that even after the heart stops beating there is still activity in the brain, it finishes with a final wave of activity that sweeps across the brain occurring minutes after the heart finishes beating, termed spreading depolarisation. The activity detected in humans in these studies is large enough to be detected by an electroencephalogram . Studies in other organisms have suggested that even 48-96 hours after death, gene expression and activity is still occurring and in some cases increasing in quantity.
Further research and understanding are needed in humans to truly establish what the activity being detected after death is and how this relates to function and the conscious versus unconscious activity.
The most famous case of surviving is probably that of Mike. Mike survived being decapitated for 18 months. How, you might ask? Well, it appears the supposedly fatal cut managed to cut at an angle through his brainstem, keeping the parts of his central nervous system that control his basic functions alive. A timely and well-placed blood clot stopped him from bleeding to death.
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What To Learn From The Pig Study
The study of revived pig brain cells does not even come close to touching on this much bigger picture. It is limited to showing that the time span and spectrum of nerve cell function that can persist and at least partially be restored is longer than had been shown so far. Hence, it supports the idea that dying is a process, and puts an additional piece of data on the length of this process.
But it does not show that these brain cells were able to function as a nerve cell network leading to higher brain function such as consciousness or awareness the features that set us apart as humans. It also just looks at the immediate restoring of cell function, and not at how these brains do days out, when the continuing processes of secondary brain damage set in.
To summarize, in the absence of blood flow, the brain, including all its individual cells will die eventually. And this study has perhaps expanded the understanding of eventually.
Death is a process, and not a moment in time. It is the human desire to put things in categories of black and white, and to have definitions that let us operate in daily life. Death this is becoming more and more clear is a large gray zone, and we will have to expect that this gray zone grows as science progresses.
Postmortem Gene Expression And Neurological Disorders
In a news release, researcher Dr. Jeffrey Loeb explained that the postmortem behavior of glial cells isnt particularly surprising. They are inflammatory and their job is to clean things up after brain injuries like oxygen deprivation or stroke, Loeb said. However, the implications of the findings could be profoundly important to the study of neurological disorders. As Science Daily explains, most research that uses postmortem human brain tissues to study neurological disorders does not account for postmortem cell activity. Most studies assume that everything in the brain stops when the heart stops beating, but this is not so, Loeb said. This could revolutionize the study of neurological disorders ranging from autism spectrum disorders to Alzheimers disease. Our findings dont mean that we should throw away human tissue research programs, it just means that researchers need to take into account these genetic and cellular changes, and reduce the postmortem interval as much as possible to reduce the magnitude of these changes, Loeb said.
As expected, the behavior of brain cells like glial cells in the postmortem period has far-reaching consequences. This groundbreaking understanding of gene and cell behavior can inform the study of neurological conditions. From Alzheimers disease to autism spectrum disorders, the study could revolutionize future treatments.
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Hair & Nails Appear Longer
Your hair and nails can get longer after you die. But there’s a reason for this that doesn’t actually have anything to do with your body producing more hair. “It is believed that hair and nails continue growing after a body dies, but this is not necessarily the case,” says Rappaport. “Skin starts to recede as moisture begins to leave the body, so over time it appears that hair and nails continue growing after death.”
This is also why some men appear to have grown a beard after they die. As Hammond said, “The skin on a dead manâs chin also dries out. As it does so it pulls back towards the skull, making stubble appear more prominent. Goosebumps caused by the contraction of the hair muscles can add to the effect.”
The Brain Remains Active
Once your heart stops beating, it’s possible for your brain to sort of know it’s dead. Recent studies have shown that animals experience a surge in brain activity in the minutes after death. And, what’s more, is that people in the first phase of death can experience some form of consciousness. For example, according to Live Science, some people whose hearts have stopped can describe what happened to them, once their hearts are restarted.
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Make Arrangements For After Death
If the person was in hospice, a plan for what happens after death will already be in place. If death happens at home without hospice, try to talk with the doctor, local medical examiner , your local health department, or a funeral home representative in advance about how to proceed. You can also consider a home funeral, which is legal in most states.
Arrangements should be made to pick up the body as soon as the family is ready and according to local laws. This can be done by a funeral home or by the family themselves in most states. The hospital or nursing facility, if that is where the death took place, may help with these arrangements. If at home, you will need to contact the funeral home directly, make arrangements yourself, or ask a friend or family member to do that for you.
The doctor may ask if you want an autopsy. This is a medical procedure conducted by a specially trained physician to learn more about what caused the death. For example, if the person who died was believed to have Alzheimers disease, a brain autopsy will allow for a definitive diagnosis. If your religion or culture objects to autopsies, talk to the doctor. Some people planning a funeral with a viewing worry about having an autopsy, but the physical signs of an autopsy are usually hidden by clothing and other body preparation techniques.
Signs That Life May Be Ending
Its not usually possible to predict exactly when someone might die, but there are some signs that show someone is close to the end of their life. In the final days and hours, they may become drowsier, or stop eating and drinking. They can appear confused or restless.
Their breathing can change, and become less regular. It may be noisy, due to fluids building up in the airways. This doesnt always cause distress to the person, but can be worrying for people around them. Some things can help, such as raising their upper body or suction treatment, and medication can be given if needed.
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At Hour 12 And Beyond
After reaching a state of maximum rigor mortis, the muscles will begin to loosen due to continued chemical changes within the cells and internal tissue decay. The process, known as known as secondary flaccidity, occurs over a period of one to three days and is influenced by external conditions such as temperature.
During secondary flaccidity, the skin will begin to shrink, creating the illusion that hair and nails are growing. Rigor mortis will then dissipate in the opposite directionfrom the fingers and toes to the faceover a period of up to 48 hours.
Once secondary flaccidity is complete, all of the muscles of the body will again be relaxed.
When You Die You Know Youre Dead Because Your Brain Keeps Working Scientist Claims
A new study is examining what happens to the brain after a person goes into cardiac arrest and suggests your consciousness carries on functioning after your heart stops beating.
We know we are dead when we die because our brains keep working to make us aware of what’s happening around us, haunting new research suggests.
Top medical experts have forever been at loggerheads over what happens when humans die, with anecdotal evidence of bright lights and flashes reported by people who have ‘come back’ being the cause of much debate.
However, a new study suggests your consciousness carries on functioning after your heart stops beating and your body movements fail.
This means you are essentially ‘trapped’ inside your dead body with your brain still working, if only for a short time.
Survivors of cardiac arrest were aware of what was going on around them while they were ‘dead’ before being ‘brought back to life’, the study revealed.
More surprising still, there is evidence to suggest the deceased may even hear themselves being pronounced dead by doctors.
Dr. Sam Parnia is studying consciousness after death and examining cardiac arrest cases in Europe and the US.
He says people in the first phase of death may still experience some form of consciousness.
Explaining when a patient is officially declared dead, he said: “It’s all based on the moment when the heart stops.
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Tales Of Heads Trying To Speak After Being Cut Off Include Anne Boleyn And Jean
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When Jean-Paul Marats killer, Charlotte Corday, was executed by guillotine in 1793, a man named Francois le Gros allegedly lifted her head and slapped both cheeks. Onlookers claimed that Cordays face took on an angry expression and her cheeks became flushed. There are other reports from history of severed heads that seem to have shown signs of consciousness. Anne Boleyn, for example, apparently tried to speak after being beheaded. But are these stories bogus or is there scientific evidence that the head can remain conscious after it has been separated from the body that sustains it?
In recent years there has been significant interest in what has been called the worlds first potential human head transplant. If it were to go ahead and that is increasingly unlikely the transplant would push multiple boundaries of science. The most obvious one being how long and whether the head and its contents might survive following removal from its original body.
The brain and all the structures it supplies need oxygen to function . Once the blood vessels in the neck are severed, the oxygen supply is halted. Whatever oxygen remains in the blood and tissues after the fatal blow would certainly be there for use, but it wouldnt last long.
Brain Removal For Brains Undergoing A Postmortem
If you happen to die in a way that clinicians or your family thinks warrants a postmortem, the process won’t look as pretty as it does on television . Postmortems are generally done to diagnose a whole-body cause of death, but the doctors doing the diagnosing do as much as possible to avoid damaging the face, in case the family would like an open-casket funeral. To that end, a brain being examined in a postmortem is accessed through an incision in the back of the skull, which is not visible from the front.
It’s first examined inside the skull, and then gently removed for further tests. And yes, they do need to take the whole thing: taking a small sliver won’t give doctors a full picture of what happened, which tends to be the problem with diagnosing from biopsies .
Oddly enough, when doctors take cell tissue cultures from brains within an eight hour window immediately following death, those tissues can be kept “alive” for a few weeks. That doesn’t mean your brain still works, though the cells respond to stimuli, but they’ve been sliced out of the brain in exceptionally thin parts and carefully put in a petri dish, so they don’t engage in any real neural functioning.
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