But, if you do know death is approaching and understand what will happen, then you do have a chance to plan. Listen carefully to what doctors and nurses are saying. They may be suggesting that death could be soon. You might also ask—how much time do you think my loved one has left, based on your experience with other patients in this condition?
Just as each life is unique, so is each death. But, there are some common experiences very near the end:. Each of these symptoms, taken alone, is not a sign of death. Most internal organs are devoid of microbes when we are alive. Soon after death, however, the immune system stops working, leaving them to spread throughout the body freely. This usually begins in the gut, at the junction between the small and large intestines.
Left unchecked, our gut bacteria begin to digest the intestines — and then the surrounding tissues — from the inside out, using the chemical cocktail that leaks out of damaged cells as a food source. Then they invade the capillaries of the digestive system and lymph nodes, spreading first to the liver and spleen, then into the heart and brain. Bacteria convert the haemoglobin in blood into sulfhaemoglobin Credit: Science Photo Library. Javan and her team took samples of liver, spleen, brain, heart and blood from 11 cadavers, at between 20 and hours after death.
They used two different state-of-the-art DNA sequencing technologies, combined with bioinformatics, to analyse and compare the bacterial content of each sample. The samples taken from different organs in the same cadaver were very similar to each other but very different from those taken from the same organs in the other bodies.
This may be due partly to differences in the composition of the microbiome of each cadaver, or it might be caused by differences in the time elapsed since death. An earlier study of decomposing mice revealed that although the microbiome changes dramatically after death, it does so in a consistent and measurable way. The researchers were able to estimate time of death to within three days of a nearly two-month period. It showed that the bacteria reached the liver about 20 hours after death and that it took them at least 58 hours to spread to all the organs from which samples were taken.
Thus, after we die, our bacteria may spread through the body in a systematic way, and the timing with which they infiltrate first one internal organ and then another may provide a new way of estimating the amount of time that has elapsed since death.
One thing that does seem clear, however, is that a different composition of bacteria is associated with different stages of decomposition. The microbiome of bacteria changes with each hour after death Credit: Getty Images. Scattered among the pine trees in Huntsville, Texas, lie around half a dozen human cadavers in various stages of decay.
The two most recently placed bodies are spread-eagled near the centre of the small enclosure with much of their loose, grey-blue mottled skin still intact, their ribcages and pelvic bones visible between slowly putrefying flesh. A few metres away lies another, fully skeletonised, with its black, hardened skin clinging to the bones, as if it were wearing a shiny latex suit and skullcap.
Further still, beyond other skeletal remains scattered by vultures, lies a third body within a wood and wire cage. It is nearing the end of the death cycle, partly mummified. Several large, brown mushrooms grow from where an abdomen once was. For most of us the sight of a rotting corpse is at best unsettling and at worst repulsive and frightening, the stuff of nightmares.
Within it, a nine-acre plot of densely wooded land has been sealed off from the wider area and further subdivided, by foot-high green wire fences topped with barbed wire. In late , SHSU researchers Sibyl Bucheli and Aaron Lynne and their colleagues placed two fresh cadavers here, and left them to decay under natural conditions. Once self-digestion is under way and bacteria have started to escape from the gastrointestinal tract, putrefaction begins. This is molecular death — the breakdown of soft tissues even further, into gases, liquids and salts.
It is already under way at the earlier stages of decomposition but really gets going when anaerobic bacteria get in on the act. Every dead body is likely to have its own unique microbial signature Credit: Science Photo Library. Putrefaction is associated with a marked shift from aerobic bacterial species, which require oxygen to grow, to anaerobic ones, which do not. This causes further discolouration of the body. As damaged blood cells continue to leak from disintegrating vessels, anaerobic bacteria convert haemoglobin molecules, which once carried oxygen around the body, into sulfhaemoglobin.
The presence of this molecule in settled blood gives skin the marbled, greenish-black appearance characteristic of a body undergoing active decomposition. As the gas pressure continues to build up inside the body, it causes blisters to appear all over the skin surface. Eventually, the gases and liquefied tissues purge from the body, usually leaking from the anus and other orifices and frequently also leaking from ripped skin in other parts of the body.
Sometimes, the pressure is so great that the abdomen bursts open. Bloating is often used as a marker for the transition between early and later stages of decomposition, and another recent study shows that this transition is characterised by a distinct shift in the composition of cadaveric bacteria.
Bucheli and Lynne took samples of bacteria from various parts of the bodies at the beginning and the end of the bloat stage. They then extracted bacterial DNA from the samples and sequenced it. Flies lay eggs on a cadaver in the hours after death, either in orifices or open wounds Credit: Science Photo Library. It happens, and we can't do anything to change that. Most of the time people enjoy long, long lives. Lots of people live well into their 70s or 80s, and some live even longer.
Slowly, though, over the course of many years, the human body wears out, just like the tires on an old bicycle or the batteries in your favorite toy. When important parts of the body — like the heart or lungs or brain — wear out and stop working, the person most likely will die.
When this happens, we say this person died of "old age. Sometimes younger people die. Sometimes a person gets very sick, and despite all the hard work of doctors and medicines, nothing can keep this person's body working. If a very sick person dies, you may hear the adults around you say that person is better off now and no longer suffering.
Still, every day doctors discover more ways to prevent and treat serious illness, so the chances of a person recovering improve all the time. Other times people die suddenly, like in an accident. This may be the hardest kind of death for families and friends to deal with because it happens so fast.
There is no time for them to get used to the idea of losing someone they love. The important thing to remember about this kind of death is it's often so sudden that the person who dies feels little or no pain. We can be relieved about that. Many people believe that when someone dies only the body dies.
It is just as if a glass bottle full of water broke, and the bottle became useless. The container is gone, but what's inside — the water — remains. The part of a person that's left after the body dies is often called the "soul" or "spirit. No one really knows what happens to a person's soul after death. There are many different beliefs about that, and it's best to talk with your family to find out what they believe happens after our bodies die.
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