Algor mortis (Latin: algor—coolness; mortis—death) is the reduction in body temperature following death. This is generally a steady decline until matching ambient temperature, although external factors can have a significant influence.
A measured rectal temperature can give some indication of the time of death. The Glaister equation, for example, is (98.4° F − rectal temperature)/1.5, giving hours elapsed since death.
As decomposition occurs the internal body temperature tends to rise again.
Rigor mortis is a recognizable sign of death that is caused by a chemical change in the muscles, causing the limbs of the corpse to become stiff (Latin "rigor") and difficult to move or manipulate. Assuming mild temperatures, rigor usually sets in about 3-4 hours after clinical death, with full rigor being in effect at about 12 hours, and eventually subsiding to relaxation at about 36 hours. Times for the onset of rigor mortis can vary from a few minutes to several hours depending on the temperature of the environment in which the body is found.
The biochemical cause of rigor mortis is hydrolysis of ATP in the muscle tissue, the chemical energy source required for movement. Myosin molecules devoid of ATP become permanently adherent to actin filaments to form actomyosin complex, causing muscles to become rigid. After the pH of the muscle has become 5.5, release of autolytic enzymes stored in lysosomes will take place. The major proteolytic enzymes are Cathepsins and Calpains. These enzymes act at the myofibrillar proteins and hydrolyse them. As a result, the actomyosin complex is broken down and muscles become "soft" again. This is known as resolution of rigor.
Livor mortis or postmortem lividity, one of the signs of death, is a settling of the blood in the lower (dependent) portion of the body, causing a purplish red discoloration of the skin: when the heart is no longer agitating the blood, heavy red blood cells sink through the serum by action of gravity. This discoloration does not occur in the areas of the body that are in contact with the ground or another object, as the capillaries are compressed.
Coroners can use the presence or absence of livor mortis as a means of determining an approximate time of death. The presence of livor mortis is an indication not to start CPR, or to stop it if it is in progress.
Livor mortis starts 20 minutes to 3 hours after death and is congealed in the capillaries in 4 to 5 hours. Maximum lividity occurs within 6-12 hours.
For other senses of this word, see decomposition (disambiguation).
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Decomposition is a phenomenon common in the sciences of biology and chemistry. In biology, decomposition refers to the reduction of the body of a formerly living organism into simpler forms of matter. In chemistry it refers to the breaking down of a large molecule into smaller molecules or atoms and is referred to as chemical decomposition.
The body of a living organism begins to decompose shortly after death. Such decomposition can be simplified in two stages: In the first stage, it is limited to the production of vapors. In the second stage, fluidic materials form and the flesh or plant matter begins to decompose. The science which studies such decomposition generally is called taphonomy.
Historically, the progression of decomposition of a living organism has been described as taking place in four stages: fresh (autolysis), bloat (putrefaction), decay (putrefaction and carnivores) and dry (diagenesis).
Contents [hide]
1 Constituent factors
2 Decomposition process
3 Embalming
4 Importance to forensics
5 Books
Constituent factors
The rate and the manner in which an animal body decomposes is strongly affected by a number of factors. In a roughly descending degree of importance, those factors include:
Temperature
The availability of oxygen
Prior embalming
Cause of death
Access by insects
Burial, and depth of burial
Access by scavengers
Trauma, including wounds and crushing blows
Humidity, or dryness
Rainfall
Body size and weight
Clothing
The surface on which the body rests
Generally an unembalmed adult body buried six feet deep in ordinary soil without a coffin normally takes ten to twelve years to decompose fully to a skeleton, given a temperate climate. A basic guide for the effect of environment on decomposition is given as Casper's Law (or Ratio). This states that when there is free access of air a body decomposes twice as rapidly than if immersed in water and eight times as rapidly than if buried in earth, a ratio of 1:2:8 for air, water and under pressure of earth respectively. The skeleton itself is not permanent; acids in soils can reduce it to unrecognisable components as well (this is one reason given for the lack of human remains found in the wreckage of the Titanic, even in parts of the ship considered inaccessible to scavengers). Freshly skeletonized bone is often called "green" bone and has a characteristic greasy feel. Under certain condition (normally cool, damp soil) bodies may undergo a process known as saponification and develop a waxy substance called adipocere, caused by the action of soil chemicals on the body's proteins and fats. The formation of adipocere slows decomposition by inhibiting the bacteria that cause putrefaction.
In extremely dry or cold conditions the normal process of decomposition is halted, by either lack of moisture or temperature controls on bacterial and enzymatic action, causing the body to be preserved as a mummy. Frozen mummies commonly restart the decomposition process when thawed whilst heat desiccated mummies remain so unless exposed to moisture.
The bodies of newborns who never ingested food are an important exception to the normal process of decomposition. They lack the internal microbial flora that generate much of decomposition and quite commonly mummify if kept in even moderately dry conditions.
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Decomposition process
Signs of death
Algor mortis Rigor mortis Livor mortis Decomposition
Decomposition begins at the moment of death. At this stage it is caused by two factors: autolysis, the breaking down of tissues by the body's own internal chemicals and enzymes; and putrefaction, the breakdown of tissues by bacteria. These processes release gases that are the chief source of the characteristic odour of dead bodies. These gases swell the body.
Scavengers play an important role in decomposition. Insects and other animals are typically the next agent of decomposition, assuming the body is accessible to them. The most important insects that are typically involved in the process include the fleshflies (Sarcophagidae) and blowflies (Calliphoridae). The green-bottle fly seen in the summer is a blowfly. Larger scavengers, including coyotes, dogs, wolves, foxes, rats, and mice may eat a body if it is accessible to them. Some of these animals will also remove and scatter bones.
Importance to forensics
Various sciences study the decomposition of bodies. These sciences fall under the general rubric of forensics, because the usual motive for study of the decomposition of human bodies is to determine the time and cause of death, for legal purposes:
Forensic pathology studies the clues to the cause of death found in the corpse as a medical phenomenon
Forensic entomology studies the insects and other vermin found in corpses; the sequence in which they appear, the kinds of insects, and where they are found in their life cycle are clues that can shed light on the time of death, the length of a corpse's exposure, and whether the corpse was moved.
Forensic anthropology is the branch of physical anthropology that studies skeletons and human remains, usually to seek clues as to the identity, race, and sex of their former owner.
Death is the cessation of physical life in a living organism, or the state of the deceased.
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 irreversible mortality 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 is 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 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.
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 — cessation of electrical activity in the whole brain, as opposed to just in the neo-cortex — 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 about 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. Stories of people actually being buried alive (which must assume no embalming) led one inventor in the early 20th century to design an alarm system, with a bell and a cord that could be pulled from inside the coffin.
Because of the difficulties in determining death, under most emergency protocols, a first responder is not authorized to pronounce a patient dead; some EMT training manuals, for example, specifically state that a person is not to be assumed dead unless there are clear and obvious indications that death has occurred, such as mortal decapitation, rigor mortis (rigidity of the body), livor mortis (blood pooling in the part of the body at lowest elevation), decomposition, or incineration, or other bodily damage 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.
1 The process of dying
1.1 Cell death
1.2 Physiological changes
2 Signs of approaching death
3 Causes of human death in the US
3.1 Fetal deaths
4 Consciousness after death
5 Physiological consequences of human death
6 Settlement of dead human bodies
7 Personification of death
8 Unwritten customs and superstitions
9 See also
10 External links
The process of dying
Cell death
A. Normal cellular function
Production of free energy required for vital cellular metabolism
Production of enzymatic and structural protein
Maintenance of chemical and osmotic homeostasis of cell
Cell reproduction
B. Needs of cell
Oxygen, phosphate, calcium… (C, H, N, O, P, S)
Nutritional substrates
ATP – required as a source of free energy
Intact cell membranes
Steady-state activity requires O2 consumption
Physiological changes
A. Events leading to death:
Brain ceases to supply information vital for controlling ventilation, heart rhythm, and/or vasodilation and vasoconstriction;
Lungs unable to supply O2 exchange with blood stream;
Heart and blood vessels unable to maintain adequate circulation of blood to vital tissues.
B. Cerebrovascular system:
Hemorrhage;
Pump failure;
Decreased CO2 leads to decreased PCO2 leads to Cheyne-Stokes respiration.
C. CNS problems:
Infection;
Blood vessel disruption;
Malignant tumors;
Metabolic changes:
Renal failure;
Hepatic failure;
Pancreatic failure.
D. CNS decompensation:
Early signs:
Sluggish pupils:
Non-reactive to stimuli;
Dilated and fixed - this is also an effect of certain drugs.
Confusion;
Inability to orient oneself.
Later signs:
Lethargy;
Decreased ability to perform simple cognitive functions;
Attention only by tactile, auditory or visual stimuli.
Late signs:
Stupor, sleep;
Withdrawal of purposeless involvement to stimuli without wakefulness or arousal;
Loss of bowel control.
Semi-comatose - movement occurs only with pain;
Deep coma - unresponsive to stimuli.
E. Respiratory system:
CBF;
COPD;
Infections;
Cancer metastasis.
Changes after death:
Body core temperature cooling depends a number of external factors including the environment and clothing;
Rigor mortis - begins prior to decomposition:
Muscles gradually become hard due to decreased ATP and lactic acidosis within muscle fibrils
Begins 2-4 hours after death, though the process may begin more immediately;
May disappear after 9-12 hours in a warm enough climate.
Livor mortis - begins on the point of death:
Body becomes distended;
Skin colour progressively changes from green to purple and finally to black;
Dependent areas of the body undergo this process first due to the pooling of blood;
Seen within 2 hours of death, the process of livor mortis reaches its maximum at 8-12 hours.
Causes of human death in the US
In 2002, in the United States, various common or noteworthy causes of death were:
Heart Disease: 696,947
Cancer: 557,271
Stroke: 162,672
Chronic lower respiratory diseases: 124,816
Accidents (unintentional injuries): 106,742
Diabetes: 73,249
Influenza/pneumonia: 65,681
Alzheimer's disease: 58,866
Nephritis, nephrotic syndrome, and nephrosis: 40,974
Septicemia: 33,865
Suicide: 30,622
Murder: 16,110
Statistical data from U.S. Department of Health & Human Services
Fetal deaths
These entries are controversial, as they are based on the premise that personhood begins at conception rather than birth or a particular prenatal development (See abortion debate; there are various opinions as to whether or not a fetus is an independent organism or fully human, for this reason abortion and miscarriage are not normally considered when compiling death statistics).
Spontaneous abortion (Miscarriage): Approximately 1,000,000 (This number may be considerably more, as most miscarriages aren't reported; perhaps as many as 1 in 3 pregnancies end in miscarriage).
Clinical abortions: 1,293,000
Statistical data from The Alan Guttmacher Institute, and Miscarriage Statistics.
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.
Brain death is defined as a complete and irreversible cessation of brain activity. Absence of apparent brain function is not enough. Evidence of irreversibility is also required. Brain-death is often confused with the state of vegetation.
*Traditionally, death has been defined as the cessation of all body functions, including respiration and heartbeat. Since it became possible to revive some people after a period without respiration, heartbeat, or other visible signs of life, as well as to maintain respiration and blood flow artificially using life support treatments, an alternative definition for death was needed. In recent decades, the concept of "brain death" has emerged. By brain-death criteria, a person can be pronounced legally dead even if the heart continues to beat due to life support measures. The first nation in the world to adopt the brain death as the definition of legal death was Finland in 1971. In the United States, Kansas had made a similar law at an even earlier date. (Randell T. (2004) Acta Anaesthesiol Scand. 48(2): 139–44.)
A brain-dead individual has no electrical activity and no clinical evidence of brain function on neurologic examination (no response to pain, no cranial nerve reflexes (pupillary response (fixed pupils), oculocephalic reflex, corneal reflexes), and no spontaneous respirations). It is important to distinguish between brain death and states that mimic brain death (eg. barbiturate intoxication, alcohol intoxication, sedative overdose, hypothermia, hypoglycemia, coma or chronic vegetative states). Some comatose patients can recover, and some patients with severe irreversible neurologic dysfunction will nonetheless retain some lower brain functions such as spontaneous respiration, loss of both cortex and brainstem function. Thus anencephaly, in which there is no higher brain present, is generally not considered brain death, although it is certainly an irreversible condition in which it may be appropriate to withdraw life support.
Note that brain electrical activity can stop completely, or apparently completely (a "flat EEG") for some time in deep anaesthesia or during cardiac arrest before being restored. Brain death refers only to the permanent cessation of electrical activity. Numerous people who have experienced such "flat line" experiences have reported near-death experiences, the nature of which is controversial.
It is presumed that a permanent cessation of electrical activity indicates the end of consciousness. Those who view the neo-cortex of the brain as solely responsible for consciousness, however, argue that only electrical activity there should be considered when defining death. In many cases, especially when elevated intracranial pressure prevents blood flow into the brain, the entire brain is nonfunctional; however, some injuries may affect only the neo-cortex.
The diagnosis of brain death needs to be rigorous to ascertain whether the condition is irreversible. Legal criteria vary from place to place, but generally require neurologic exams by two independent physicians. The exams must show complete absence of brain function, and may include two isoelectric (flat-line) EEGs 24 hours apart. The proposed Uniform Determination Of Death Act in the United States attempts to standardize criteria. The patient should have a normal temperature and be free of drugs that can suppress brain activity if the diagnosis is to be made on EEG criteria. Alternatively, a radionuclide cerebral blood flow scan that shows complete absence of intracranial blood flow can be used to confirm the diagnosis without performing EEGs.
*Most organ donation for organ transplantation is done in the setting of brain death. In some nations (for instance, Belgium, Poland, Portugal and France) everyone is automatically an organ donor, although some jurisdictions allow opting out from the system. Elsewhere consent from family members or next-of-kin is required for organ donation. The non-living donor is kept on ventilator support until the organs have been surgically removed. If a brain-dead individual is not an organ donor, ventilator and drug support is discontinued and cardiac death is allowed to occur.
Categories: Death | Anatomical pathology
Clinical death occurs when a patient's heartbeat and breathing have stopped. Since breathing rarely continues when the heart is stopped, clinical death is synonymous with cardiac arrest or cardiac death. The reversal of clinical death is sometimes possible through CPR, Defibrillation, Epinephrine injection, and other treatments. Resuscitation after more than 4 to 6 minutes of clinical death at normal body temperature is difficult, and can result in brain damage or later brain death even if cardiac resuscitation is successful. Longer intervals of clinical death can be survived under conditions of Hypothermia. Hypothermia also improves outcomes after resuscitation from clinical death even if body temperature is not lowered until after resuscitation.
Post mortem interval (PMI) is the time that has elapsed since a person has died. If the time in question is not known, a number of medical/scientific techniques are used to determine it.
Some of the methods used to determine PMI are as follows:
Algor mortis - body cooling.
Rigor mortis - stiffening of limbs.
Vitreous humour changes - eye chemistry.
Entomology - insect activity on the corpse.
State of decomposition (autolysis and putrefaction).
Category: Death
Autolysis is the process by which a cell self-destructs (if necessary) for the healthiness of the entire organism. It is uncommon in adult organisms and usually occurs in injured cells or dying tissue. Autolysis occurs when a lysosome allows the digestive enzymes out of its membranes. The cell then, in effect, digests itself.
Thanatology is the scientific study of death. It investigates the circumstances surrounding death, the grief experienced by the deceased's loved ones, and larger social attitudes towards death. It is primarily an interdisciplinary study, frequently undertaken by professionals in nursing, psychiatry, and veterinary science. It also describes bodily changes that acompany death and after-death period.
The word is derived from the Greek language. In Greek mythology, Thanatos (θάνατος: "death") is the personification of death. The English suffix -ology derives from the Greek suffix -logia (-λογια: "speaking").
Goals
In most cases, thanatology is studied as a means towards the end of providing palliative care for dying individuals and their families. According to the World Health Organization, "palliative care is an approach that improves the ...
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