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Signs of biological death

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Signs of death or strong indications that a warm-blooded animal is no longer alive are:

Cessation of breathing
Cardiac arrest (no pulse)
Pallor mortis, paleness which happens in the 15–120 minutes after death
Livor mortis, a settling of the blood in the lower (dependent) portion of the body
Algor mortis, the reduction in body temperature following death.

This is generally a steady decline until matching ambient temperature
Rigor mortis, the limbs of the corpse become stiff (Latin rigor) and difficult to move or manipulate
Decomposition, the reduction into simpler forms of matter, accompanied by a strong, unpleasant odor. Algor mortis. Algor mortis (Latin: algor—coldness; mortis—of death) is the reduction in body temperature following death.

Algor mortis

This is generally a steady decline until matching ambient temperature, although external factors can have a significant influence. Use in forensic science and crime solving[edit] A measured rectal temperature can give some indication of the time of death. Although the heat conduction which leads to body cooling follows an exponential decay curve, it can be approximated as a linear process: 2° Celsius during the first hour and 1° Celsius per hour until the body nears ambient temperature. Cardiac arrest. Cardiac arrest, also known as cardiopulmonary arrest or circulatory arrest, is a sudden stop in effective blood circulation due to failure of the heart to contract effectively or at all.[1] Medical personnel may refer to an unexpected cardiac arrest as a sudden cardiac arrest (SCA).

Cardiac arrest

A cardiac arrest is different from (but may be caused by) a heart attack, where blood flow to the muscle of the heart is impaired.[2] It is different from congestive heart failure, where circulation is substandard, but the heart is still pumping sufficient blood to sustain life. Arrested blood circulation prevents delivery of oxygen and glucose to the body. Lack of oxygen and glucose to the brain causes loss of consciousness, which then results in abnormal or absent breathing. Brain injury is likely to happen if cardiac arrest goes untreated for more than five minutes.[3][4][5] For the best chance of survival and neurological recovery, immediate and decisive treatment is imperative.[6] Classification[edit] Hs Ts. Decomposition. Decomposition is the process by which organic substances are broken down into a much simpler form of matter.

Decomposition

The process is essential for recycling the finite matter that occupies physical space in the biome. Bodies of living organisms begin to decompose shortly after death. Although no two organisms decompose in the same way, they all undergo the same sequential stages of decomposition. The science which studies decomposition is generally referred to as taphonomy from the Greek word τάφος taphos, meaning tomb. One can differentiate abiotic from biotic decomposition (biodegradation). Animal decomposition[edit] Prime decomposers are bacteria or fungi, though larger scavengers also play an important role in decomposition if the body is accessible to insects, mites and other animals.

Livor mortis. Livor mortis (Latin: livor—"bluish color," mortis—"of death"), postmortem lividity (Latin: postmortem—"after death", lividity—"black and blue"), hypostasis (Greek: hypo, meaning "under, beneath"; stasis, meaning "a standing"[1][2]) or suggillation, is one of the signs of death.

Livor mortis

Livor mortis 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 stops functioning and is no longer agitating the blood, heavy red blood cells sink through the serum by action of gravity. 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 also an indication of when it would be futile to begin CPR, or when it would be ineffective to continue if it is in progress. Calixto Machado, "Brain death: a reappraisal", Springer, 2007, ISBN 0-387-38975-X, p. 74Robert G. Pallor mortis. Rigor mortis. Rigor mortis (Latin: rigor "stiffness", mortis "of death") is one of the recognizable signs of death, caused by chemical changes in the muscles after death, causing the limbs of the corpse to become stiff and difficult to move or manipulate.[1] In humans, it commences after about three to four hours, reaches maximum stiffness after 12 hours, and gradually dissipates from approximately 24 hours after death.[2] Biochemistry[edit] After death, ventilation in organisms ceases to occur, depleting the corpse of oxygen used in the making of adenosine triphosphate (ATP).

Rigor mortis

ATP is no longer provided to operate the SERCA pumps in the membrane of the sarcoplasmic reticulum, which pump calcium ions into the terminal cisternae.[1] This prevents calcium ions from leaving the muscle fibre and hence calcium ions keep on binding with troponin causing the cross-bridge to remain between myosin heads and actin proteins. Physical changes[edit] Applications in meat industry[edit] See also[edit] Cadaveric spasm.