Death

Death is the cessation of physical life in a living organism or the state of the organism after that event. In almost all societies, death has one or several symbols associated with it. Common symbols of death in Western cultures include the grim reaper and the color black; conversely, in certain Eastern cultures, the color white is considered symbolic of death. The grave is a metonym for death.

Related Topics:
Life - Organism - Grim reaper - Grave - Metonym

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Biologically, death can occur to wholes, to parts of wholes, or to both. For example, it is possible for individual cells and even organs to die, and yet for the organism as a whole to continue to live; many individual cells can live for only a short time, and so most of an organism's cells are continually dying and being replaced by new ones.

Related Topics:
Cell - Organ

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Conversely, it is also possible for the organism to die and for cells and organs to live and to be used for transplantation. In the latter case, though, the still-living tissues must be removed and transplanted quickly or they too will soon die without the support of their host. Rarely, cell cultures can be "immortal" as in the case of Henrietta Lacks' HeLa cell line.

Related Topics:
Transplantation - Henrietta Lacks' - HeLa cell

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Irreversibility is often cited as a key feature of death. By definition, a dead organism cannot be brought back to life; if it were to be, that would indicate that it had never been dead. Nonetheless, many people do not believe that death is necessarily irreversible; thus some have a religious belief in bodily or spiritual resurrection, while others have hope for the eventual prospects of cryonics or other technological means of reversing death.

Related Topics:
Religious - Resurrection - Cryonics

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It has been hypothesized that a limited lifespan is a consequence of evolution not of selecting for extreme longevity in most species, as evolutionary selection only need apply to the organism up to the point of reproduction; after that, except for caring for kin, the continued existence of an individual can have little effect on the survival of its gene line. A common assumption is that the Second Law of Thermodynamics dictates that all complex systems must eventually deteriorate, so it is not likely that any species could ever be immortal. However, this aspect of the Second Law of Thermodynamics only applies to closed systems, which a living organism obviously is not.

Related Topics:
Evolution - Longevity - Second Law of Thermodynamics - Immortal

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