:For other uses, see Death (disambiguation).Death is the full cessation of vital functions in the biological life. This article discusses death in the biological sense of the term, and its place in various cultures.
Normal cellular function involves the production of free energy required for vital cellular metabolism, the production of enzymatic and structural protein, the maintenance of chemical and osmotichomeostasis of cell, and cell reproduction. During normal functions, cells require oxygen, phosphate, calcium (C, H, N, O, P, S), nutritional substrates, ATP, which is required as a source of free energy, intact cell membranes, and a steady-state activity that requires O2 consumption. Cell death may occur when any of these functions is interrupted.
Changes after death
After death, the body core temperature cools (algor mortis). Rate and degree of the cooling depends on a number of external and cadaveric factors including the environment, clothing, body temperature at time of death and size of the body.
Furthermore, rigor mortis begins prior to decomposition. During this process, the muscles gradually stiffen due to decreasing availability of ATP and lactic acidosis within muscle fibrils. This usually begins 2-4 hours after death, though the process may begin earlier. After 9-12 hours, or in a warm enough climate, these effects may disappear. Onset and duration of rigor mortis are influenced by environmental temperature and the degree of muscular activity prior to onset of death.
Another post mortem reaction includes livor mortis. Fibrolysins (lytic enzymes) are released from serous membranes, and cause lytic degradation of fibrinogen (which is responsible for the clotting of blood). Due to this process, blood becomes permanently incoaguable (unable to clot) within 30-60min after death. Gravitational pooling of blood results in characteristic changes in skin colour, starting with those areas that support the body on whatever surface it is lying on. This is usually seen within 2 hours of death, with the process of livor mortis reaching its maximum at 8-12 hours. The colour of the post mortem lividity differs with cause of death and environmental conditions. The distribution of the lividity depends on the position of the body and the pressure at the location.
Decomposition of a body progresses in the following stages:
#Autolysis: The "self digestion" of the body driven by its own enzymes. Cell membranes lose their structural integrity, lytic enzymes are released and denature macromolecules and remaining membranes. Autolysis occurs first in the most metabolically active cells, secretory cells and macrophages.#Putrefaction: Anaerobic bacterial digestion of the remains. At the end stage of autolysis, an aerobic environment is established within the corpse. This favours the growth of anaerobic bacteria of mostly endogenous (colon fauna) and to a lesser extent exogenous (soil bacteria) origin. These bacteria degrade carbohydrates, proteins and lipids of the corpse to products such as acids and gases, resulting in colour changes, odours, bloating, and liquefaction of the corpse. The rate of putrefaction is dependent on the presence of moisture and moderate environmental temperatures.#Decay: Aerobic bacterial and fungal digestion of remains. At the end stage of putrefaction, putrefactive juices have drained away and soft tissue is shrunken. All remaining tissues are in a relatively dry state. Decay is characterized by a slow breakdown of proteins by aerobic microorganisms and leads to skeletonisation of the corpse.#Diagenisis: Decomposition of hard tissues like bone and teeth. Microorganisms (bacteria, algae, fungi) invade the bone by either following physiological channels or actively penetrating the bone substance. The latter is accomplished by excretion of acidic and/or enzymatic metabolites which results in characteristic non-physiological cavities or channels, the so called "drill channels." The invading microorganisms metabolize the organic bone matrix. The resulting metabolites destroy the surrounding mineral matrix. Furthermore, the decomposition of the mineral matrix, which is composed of crystalline calcium phosphates, is influenced by chemical factors from the environment. An acidic environment results in dissolution of calcium phosphates which partly leads to demineralisation of the bone, and partly is followed by re-crystallisation to molecules that are significantly larger than the original ones and more water soluble. These processes result in micro- and macrostructural disintegration (cracking) in the first case and progressive demineralisation in the latter.
Determining when death actually occurs
Historically, attempts to define the exact moment of death have been problematic. Death was once defined as the cessation of heartbeat (cardiac arrest) and of breathing, but the development of CPR and prompt defibrillation posed a challenge, rendering the previous definition inadequate. This earlier definition of death is now called "clinical death", and even after it occurs, breathing and heartbeat may be restarted in some cases. Events which were causally linked to death in the past are now prevented from having an effect; even without a functioning heart and lungs, a person can be sustained with life-support devices. In addition to such extremes, there are a growing number of people who would quickly die if their organ transplants or cardiac pacemakers failed.
Today, where a definition of the moment of death is required, doctors and coroners usually turn to "brain death" or "biological death": people are considered dead when the electrical activity in their brain ceases (cf. persistent vegetative state). It is presumed that a stoppage of electrical activity indicates the end of consciousness. However, suspension of consciousness must be permanent, and not transient, as occurs during sleep, and especially a coma. In the case of sleep, EEGs can easily tell the difference. Identifying the moment of death is important in cases of transplantation, as organs for transplant (the brain excluded) must be harvested as quickly as possible after the death of the body.
Among human beings, brain activity is a necessary condition to legal personhood in the United States. "It appears that once brain death has been determined … no criminal or civil liability will result from disconnecting the life-support devices." (Dority v. Superior Court of San Bernardino County, 193 Cal.Rptr. 288, 291 (1983))
However, those maintaining that only the neo-cortex of the brain is necessary for consciousness sometimes argue that only electrical activity there should be considered when defining death. Eventually it is likely that the criterion for death will be the permanent and irreversible loss of cognitive function, as evidenced by the death of the cerebral cortex. All hope of recovering human thought and personality is then gone. However, at present, in most places the more conservative definition of death â€" cessation of electrical activity in the whole brain, as opposed to just in the neo-cortex â€" has been adopted (for example the Uniform Determination Of Death Act in the United States). In 2005, the case of Terri Schiavo brought the question of brain death and artificial sustainment to the front of American politics. Generally, in such contested cases the cause of death is anoxia. Oxygen deprivation for roughly seven minutes is sufficient to kill the cerebral cortex.
Even in these cases, the determination of death can be difficult. EEGs can detect spurious electrical impulses when none exists, while there have been cases in which electrical activity in a living brain has been too low for EEGs to detect. Because of this, hospitals often have elaborate protocols for determining death involving EEGs at widely separated intervals.
There are many anecdotal references to people being declared dead by physicians and then coming back to life, sometimes days later in their own coffin, or when embalming procedures are just about to begin. Owing to significant scientific advancements in the Victorian era, some people in Great Britain became obsessively worried about living after being declared dead. Being buried alive was a particular possibility which concerned many; inventors therefore created methods of alerting the outside world to one's status: these included surface bells and flags connected to the coffin interior by string, and glass partitions in the coffin-lid which could be smashed by a hammer or a system of pulleys (what many failed to realise was that the pulley system would either not work due to the soil outside the coffin, or that the glass would smash in the person's face, covering them in broken glass and earth).
A first responder is not authorized to pronounce a patient dead. Some EMT training manuals specifically state that a person is not to be assumed dead unless there are clear and obvious indications that death has occurred. These indications include mortal decapitation, rigor mortis (rigidity of the body), livor mortis (blood pooling in the part of the body at lowest elevation), decomposition, incineration, or other bodily damage that is clearly inconsistent with life. If there is any possibility of life and in the absence of a do not resuscitate (DNR) order, emergency workers are instructed to begin rescue and not end it until a patient has been brought to a hospital to be examined by a physician. This frequently leads to situation of a patient being pronounced dead on arrival (DOA).
In cases of electrocution, CPR for an hour or longer can allow stunned nerves to recover, allowing an apparently-dead person to survive. People found unconscious under icy water may survive if their faces are kept continuously cold until they arrive at an emergency room. This "diving response", in which metabolic activity and oxygen requirements are minimal, is something we share with cetaceans (whales, dolphins, etc).
Signs of approaching death
When death is imminent
Physical death is a progressive process, during which there are some signs that usually indicate that death is imminent. Not all of the following changes occur, nor do they necessarily occur in any particular order, as the body shuts down during the dying process. In general, the following information may help anticipate and understand changes that appear as an individual approaches death and is "actively dying." * The dying individual may become increasingly tired and sleepy, and may be difficult to arouse (lethargy). * The individual may become confused much of the time and may no longer recognize familiar persons, places, or objects. * Hearing and vision may become impaired, and speech may be slurred, difficult to understand, or nonsensical. * A few dying individuals become restless or very anxious and move about frequently in the bed, pull at the bed clothes or bedding (linen clutch) and reach out. * The person may experience hallucinations. * Less nourishment will be required, and the person's intake of food and water will diminish. Difficulty in swallowing (dysphagia) may also occur. * The person may sweat profusely. * The dying person may lose control of his/her urine or bowels (incontinence), necessitating that the individual be kept especially clean and dry to prevent bed sores (decubitis ulcers). * Urine may become darker, and urination may diminish or stop. * The mouth of the dying individual may become dry, and then secretions may accumulate in the back of the throat. Breathing may become noisy because of the gurgling or rattling of the secretions in the mouth or chest (death rattle). * The pattern of breathing may change; become slower or faster, deeper or shallower, or irregular. Often the dying individual will have periods of rapid breathing followed by periods in which breathing is very slow or is even absent for as long as 15 seconds (Cheyne-Stokes respiration). * The legs, and then arms, may become cold and nonreflexive as the circulation slows down. * The skin may be pale or mottled, and some parts, particularly the underside of the body, may become a dark color as the blood pools, usually a deep blue or purple.
When death occurs
* Breathing ceases entirely. * Heartbeat and pulse stop. * The person is entirely unresponsive to stimuli. * The eyes may be fixed in directions. The pupils are dilated and fixed to light. The eyelids may be open or closed. * A loss of control of urine and/or bowels may occur. * The skin may become pale (known as pallor mortis); there may be signs of blood buildup in the part of the body at lowest elevation (known as Livor mortis). * The person becomes progressively mottled and cold (algor mortis) and stiff (rigor mortis).
There are private companies and institutions such as HopeXchange and The Alan Guttmacher Institute which track death statistics involving embryos and fetuses: * Miscarriage: Approximately 1,000,000 per year (This number may be considerably larger, as most miscarriages are unreported; perhaps as many as 1 in 3 pregnancies end in miscarriage). * Clinical abortion: 1,293,000
Consciousness after death
Belief in consciousness continuing after death is common and has endured throughout history. Almost every civilization in history has had some belief system relating to life after death. This point of view holds that consciousness is more than simply a function of the brain.
Physiological consequences
Human remains found in scrub, circa 1900-1910.
For the human body, the physiological consequences of death follow a recognized sequence through early changes into bloating, then decay to changes after decay and finally skeletal remains.
Soon after death (15–120 minutes depending on various factors), the body begins to cool (algor mortis), becomes pallid (pallor mortis), and internal sphincter muscles relax, leading to the release of urine, feces, and stomach contents if the body is moved. The blood moves to pool in the lowest parts of the body, livor mortis (dependent lividity), within 30 minutes and then begins to coagulate. The body experiences muscle stiffening (rigor mortis) which peaks at around 12 hours after death and is gone in another 24 (depending on temperature) as enzymes begin to break down the tissues. Within a day, the body starts to show signs of decomposition (decay), both autolytic changes and from 'attacking' organisms—bacteria, fungi, insects, mammalian scavengers, etc. Internally, the body structures begin to collapse, the skin loses integration with the underlying tissues, and bacterial action creates gases which cause bloating and swelling. The rate of decay is enormously variable and depends on numerous factors. Thus, a body may be reduced to skeletal remains in days, though it is possible under certain conditions for remains to stay largely intact for many years.
Settlement of dead bodies
In most cultures, before the onset of significant decay, the body undergoes some type of ritual disposal, usually either cremation or deposition in a tomb. This is often a grave, but may also be a sarcophagus, crypt, sepulchre, or ossuary, a mound or barrow, or a monumental surface structure such as a mausoleum (exemplified by the Taj Mahal) or a pyramid (as exemplified by the Great Pyramid of Giza).
In Tibet, one method of corpse disposal is sky burial, which involves placing the body of the deceased on high ground (a mountain) and leaving it for birds of prey to dispose of. Sometimes this is because in some religious views, birds of prey are carriers of the soul to the heavens, but at other times this simply reflects the fact that when terrain (as in Tibet) makes the ground too hard to dig, there are few trees around to burn and the local religion (Buddhism) believes that the body after death is only an empty shell, there are more practical ways of disposing of a body, such as leaving it for animals to consume.
In certain cultures, efforts are made to retard the decay processes before burial (resulting even in the retardation of decay processes after the burial), as in mummification or embalming. This happens during or after a funeral ceremony. Many funeral customs exist in different cultures. In some fishing or navy communities, the body is sent into the water, in what is known as burial at sea. Several mountain villages have a tradition of hanging the coffin in woods.
A new alternative is ecological burial. This is a sequence of deep-freezing, pulverisation by vibration, freeze-drying, removing metals, and burying the resulting powder, which has 30% of the body mass.
Space burial uses a rocket to launch the cremated remains of a body into orbit. This has been done at least 150 times.
Graves are usually grouped together in a plot of land called a cemetery or graveyard, and burials can be arranged by a funeral home, mortuary, undertaker or by a religious body such as a church or (for some Jews) the community's Burial Society, a charitable or voluntary body charged with these duties. In some places this has created a land-use problem. For example, in Japan all people are cremated after death. About 10% of the arable land in China is taken up by graves.
Customs and superstitions
In China, Japan, Korea, and Taiwan the number 4 is often associated to death due to the sound of the Chinese, Japanese, and Korean words for four and death being similar (for example, 사 in Korean is the Sino-Korean number 4 and the word for death, as in 뇌사 (brain death)). For this reason, hospitals and hotels often omit the 4th, 14th, etc. floors, or substitute the number 4 for the letter 'F'.
"All Is Vanity" by C. Allan Gilbert, suggesting an intertwinement between life and death.
Death is also a mythological figure who has existed in popular culture since the earliest days of storytelling. The traditional Western image of Death, known as the Grim Reaper—usually resembling a skeleton, wearing black robes and carrying a scythe—is employed on a tarot card and in various television shows and films. Some examples: * Thanatos in addition to the term Freud used to denote the "death instinct" in human beings is also a mythological personification of death * In the Warhammer 40000 universe, the Nightbringer is a god-like alien creature of the C'Tan race which styles itself as a grim reaper. The Nightbringer is said to be responsible for the dread of death felt by all mortals, and it feeds maliciously on this implanted fear. *Death is a major character in the Discworld series by Terry Pratchett. *Humorous depictions of Death, often with a Grim Reaper-esque feel, are common during the DÃa de los Muertos in Mexico, especially in the state of Michoacán. *An unusual personification of Death as a goth woman appears in Neil Gaiman's Sandman graphic novels. *In Ingmar Bergman's The Seventh Seal, a knight plays a game of chess against Death. *Death is portrayed as a neurotic Grim Reaper-esque character who still lives with his mother in Family Guy. He appeared in several episodes to date and in one episode, Peter Griffin must take on the responsibilities of Death after Death sprains his ankle. *In the film Meet Joe Black, a remake of Death Takes a Holiday (written by Alberto Casella), Death (Brad Pitt) inhabits the body of a young man to experience life firsthand. *In the film Bill & Ted's Bogus Journey, Death is the bassist for Wyld Stallyns. *In the TV series Dead Like Me, the main characters are all Grim Reapers as part of a post-life bureaucracy. *In the series The Glam Metal Detectives, a regular feature saw the stars being chased by Death, whose appearance was modelled on the director's friend Allan Yates. *The series Touched by an Angel featured the Angel of Death as a regular character, depicted as a kindly, soft-spoken man in his mid-30s. *The Angel of Death also appeared in the show Charmed as a man who appeared before those who had died to take them to the afterlife. He was neither good nor evil. (spoiler) Marty, the Angel of Death is also the one who gives Michael Newman (Adam Sandler) his remote control in Click (film). *Death is also a recurring character in the Castlevania video games. He is usually described as Dracula's servant, and is therefore evil. He is almost always a boss, and appears usually near the end of the game. He uses the scythe, and often transforms into more hideous forms. Plus, he has one trademark attack: Often during the whole battle, he will constantly summon small sickles/scythes out of thin air to attack the player. *Death 'stalks' people who avoided their demises in the Final Destination series. *Death appears as a character in a sketch in the Monty Python film The Meaning of Life. *In the cartoon Futurama, Death is represented by the "Sunset Squad", a group of robots who take people away to the Near-Death Star when they reach the age of 160. *In the book On a Pale Horse, by Piers Anthony, the main character becomes Death himself after killing the previous Death. *In the cartoonThe Grim Adventures of Billy and Mandy, death is The Grim Reaper, usually called Grim (the character speaks with a Jamaican/Rastifarian accent), and is the forced best friend of Billy and Mandy. *Death appeared in the South Park episode entitled Death. In it, Death appears after Grandpa Marsh attempts to kill himself, and instead goes after Kenny, a character famous for dying. *The Finnish band Children of Bodom use the Grim Reaper as a mascot or symbol of sorts. *In the video game The Sims 2, if a Sim dies, the Grim Reaper appears so the sim could purchase their life back. *Peter Kay talked about death in one of his stand up shows. He suggested that the Grim Reaper was very camp â€" "Hold me scythe, me wrists are aching! Is it hot in here or is it me?" *In the game Grim Fandango, the main character â€" Manuel Calavera â€" is one of several Grim Reapers working for "The Department of Death". *In the anime BLEACH, there is a society of Soul Reapers (Shinigami) whose jobs include the purification of souls and escorting them to their destination. Known as Shinigami, they are invisible, wield personalized, shape changing swords, and can be killed by other spirits. *Peter S. Beagle wrote "Come Lady Death", in which rich Lady Neville invites Death to a party. Death appears as a beautiful woman with light hair and black eyes. When it comes time for her to leave, the guests ask her to stay, and after asking if they are sure, she agrees, then explains that one of them must take her place. No one volunteers, so Death chooses someone according to who she thought would do a good job. She is neither good, nor evil. *In Romancing SaGa: Minstrel Song Death is the eldest sibling of evil. Saruin the middle child and Shirach the sister. *Death features a number of times in the short stoies of Fritz Leiber. In "The Price of Pain-Ease", Fafyrd and the Grey Mouser are dispatched to steal the mask of Death from his fortress in the Shadowlands, while "The Sadness of the Executioner" follows Death himself in an attempt to claim the lives of the two heroes. In the non-Nehwon "Gonna roll the Bones" Death appears as an inhumanly skilful gambler.
