World Health Organization estimated number of<unk> s per million persons in 2012 Problems of definition A flower, a skull and an hourglass stand for life,<unk>  and time in this 17th-century painting by Philippe de Champaigne French – 16th-/17th-century ivory pendant, Monk and<unk> , recalling mortality and the certainty of<unk>  (Walters Art Museum) The concept of<unk>  is a key to human understanding of the phenomenon. There are many scientific approaches and various interpretations of the concept. Additionally, the advent of life-sustaining therapy and the numerous criteria for defining<unk>  from both a medical and legal standpoint, have made it difficult to create a single unifying definition. One of the challenges in defining<unk>  is in distinguishing it from life. As a point in time,<unk>  would seem to refer to the moment at which life ends. Determining when<unk>  has occurred is difficult, as cessation of life functions is often not simultaneous across organ systems. Such determination, therefore, requires drawing precise conceptual boundaries between life and<unk> . This is difficult, due to there being little consensus on how to define life. It is possible to define life in terms of consciousness. When consciousness ceases, an organism can be said to have died. One of the flaws in this approach is that there are many organisms that are alive but probably not conscious (for example, single-celled organisms). Another problem is in defining consciousness, which has many different definitions given by modern scientists, psychologists and philosophers. Additionally, many religious traditions, including Abrahamic and Dharmic traditions, hold that<unk>  does not (or may not) entail the end of consciousness. In certain cultures,<unk>  is more of a process than a single event. It implies a slow shift from one spiritual state to another. Other definitions for<unk>  focus on the character of cessation of something. More specifically,<unk>  occurs when a living entity experiences irreversible cessation of all functioning. As it pertains to human life,<unk>  is an irreversible process where someone loses their existence as a person. Historically, attempts to define the exact moment of a human's<unk>  have been subjective, or imprecise.<unk>  was once defined as the cessation of heartbeat (cardiac arrest) and of breathing, but the development of CPR and prompt defibrillation have rendered that definition inadequate because breathing and heartbeat can sometimes be restarted. This type of<unk>  where circulatory and respiratory arrest happens is known as the circulatory definition of<unk>  (DCDD). Proponents of the DCDD believe that this definition is reasonable because a person with permanent loss of circulatory and respiratory function should be considered dead. Critics of this definition state that while cessation of these functions may be permanent, it does not mean the situation is irreversible, because if CPR was applied, the person could be revived. Thus, the arguments for and against the DCDD boil down to a matter of defining the actual words "permanent" and "irreversible," which further complicates the challenge of defining<unk> . Furthermore, events which were causally linked to<unk>  in the past no longer kill in all circumstances; without a functioning heart or lungs, life can sometimes be sustained with a combination of life support devices, organ transplants and artificial pacemakers. Today, where a definition of the moment of<unk>  is required, doctors and coroners usually turn to "brain<unk> " or "biological<unk> " to define a person as being dead; people are considered dead when the electrical activity in their brain ceases. It is presumed that an end of electrical activity indicates the end of consciousness. Suspension of consciousness must be permanent, and not transient, as occurs during certain sleep stages, and especially a coma. In the case of sleep, EEGs can easily tell the difference. The category of "brain<unk> " is seen as problematic by some scholars. For instance, Dr. Franklin Miller, senior faculty member at the Department of Bioethics, National Institutes of Health, notes: "By the late 1990s... the equation of brain<unk>  with<unk>  of the human being was increasingly challenged by scholars, based on evidence regarding the array of biological functioning displayed by patients correctly diagnosed as having this condition who were maintained on mechanical ventilation for substantial periods of time. These patients maintained the ability to sustain circulation and respiration, control temperature, excrete wastes, heal wounds, fight infections and, most dramatically, to gestate fetuses (in the case of pregnant "brain-dead" women)." While "brain<unk> " is viewed as problematic by some scholars, there are certainly proponents of it that believe this definition of<unk>  is the most reasonable for distinguishing life from<unk> . The reasoning behind the support for this definition is that brain<unk>  has a set of criteria that is reliable and reproducible. Also, the brain is crucial in determining our identity or who we are as human beings. The distinction should be made that "brain<unk> " cannot be equated with one who is in a vegetative state or coma, in that the former situation describes a state that is beyond recovery. Those people maintaining that only the neo-cortex of the brain is necessary for consciousness sometimes argue that only electrical activity should be considered when defining<unk> . Eventually it is possible that the criterion for<unk>  will be the permanent and irreversible loss of cognitive function, as evidenced by the<unk>  of the cerebral cortex. All hope of recovering human thought and personality is then gone given current and foreseeable medical technology. At present, in most places the more conservative definition of<unk>  – irreversible 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<unk>  Act in the United States). In 2005, the Terri Schiavo case brought the question of brain<unk>  and artificial sustenance to the front of American politics. Even by whole-brain criteria, the determination of brain<unk>  can be complicated. EEGs can detect spurious electrical impulses, while certain drugs, hypoglycemia, hypoxia, or hypothermia can suppress or even stop brain activity on a temporary basis. Because of this, hospitals have protocols for determining brain<unk>  involving EEGs at widely separated intervals under defined conditions. In the past, adoption of this whole-brain definition was a conclusion of the President's Commission for the Study of Ethical Problems in Medicine and Biomedical and Behavioral Research in 1980. They concluded that this approach to defining<unk>  sufficed in reaching a uniform definition nationwide. A multitude of reasons were presented to support this definition including: uniformity of standards in law for establishing<unk> ; consumption of a family's fiscal resources for artificial life support; and legal establishment for equating brain<unk>  with<unk>  in order to proceed with organ donation. Aside from the issue of support of or dispute against brain<unk> , there is another inherent problem in this categorical definition: the variability of its application in medical practice. In 1995, the American Academy of Neurology (AAN), established a set of criteria that became the medical standard for diagnosing neurologic<unk> . At that time, three clinical features had to be satisfied in order to determine "irreversible cessation" of the total brain including: coma with clear etiology, cessation of breathing, and lack of brainstem reflexes. This set of criteria was then updated again most recently in 2010, but substantial discrepancies still remain across hospitals and medical specialties. The problem of defining<unk>  is especially imperative as it pertains to the dead donor rule, which could be understood as one of the following interpretations of the rule: there must be an official declaration of<unk>  in a person before starting organ procurement or that organ procurement cannot result in<unk>  of the donor. A great deal of controversy has surrounded the definition of<unk>  and the dead donor rule. Advocates of the rule believe the rule is legitimate in protecting organ donors while also countering against any moral or legal objection to organ procurement. Critics, on the other hand, believe that the rule does not uphold the best interests of the donors and that the rule does not effectively promote organ donation. Signs Signs of<unk>  or strong indications that a warm-blooded animal is no longer alive are: * Respiratory arrest (no breathing) * Cardiac arrest (no pulse) * Brain<unk>  (no neuronal activity) Timeline of postmortem changes (stages of<unk> . The stages that follow after<unk>  are: * , paleness which happens in the 15–120 minutes after<unk>  * , the reduction in body temperature following<unk> . This is generally a steady decline until matching ambient temperature * , the limbs of the corpse become stiff (Latin rigor) and difficult to move or manipulate * , a settling of the blood in the lower (dependent) portion of the body * Putrefaction, the beginning signs of decomposition * Decomposition, the reduction into simpler forms of matter, accompanied by a strong, unpleasant odor. * Skeletonization, the end of decomposition, where all soft tissues have decomposed, leaving only the skeleton. * Fossilization, the natural preservation of the skeletal remains formed over a very
Death
Brain death
Euthanasia
Poison
Clinical death
Sudden death 
Dying
Asphyxia