In medicine, the biological details and definitions relating to death are becoming increasingly complex as our technology advances and our knowledge expands. But the basic facts remain the same. What happens to an organism's physical remains after death depends on the type of organism involved, where it dies, and how it dies.
When an organism dies the following may occur:
2. Death Rattle: is a gurgling, rattle-like noise which may be produced shortly before or after death. The noise occurs because of a build-up of respiratory secretions in the throat because the animal has lost its ability to swallow properly.
3. Algor Mortis: is the decline in body temperature until ambient temperature is reached.
4. Livor Mortis: occurs when blood pools in the parts of the body which are at the lowest elevation.
5. Pallor Mortis: is paleness due to a lack of capillary circulation throughout the body.
6. Postmortem Spasms: are small movements of the limbs, such as twitching legs or wings.
7. Rigor Mortis: occurs when chemical change in the muscles cause the limbs to become stiff and difficult to move, bend, or manipulate. Under normal temperatures, rigor mortis starts and progresses slowly within a few hours of death. Full rigor usually occurs about 12 hours after death, and eventually subsides after about 36 hours. That is, after 36 hours, the limbs should be fully relaxed again.
If you are eaten or consumed by predators or scavengers, then your body will be digested and used to sustain these other organisms. Any waste material from this process will be expelled or excreted from the predator's and/or scavenger's bodies, after which it may decompose or be used by other organisms to sustain their life. Any material not consumed will decompose. And, the waste products of any material that has been consumed will be expelled and either decompose or be used by other organisms to sustain their life.
The process of decay and break down of an organisms remains. Decomposition may occur very quickly, such as during a fire. However, if the organism is left lying on the ground, or is buried, then decomposition will occur much more slowly, and may require many days, weeks, or months to complete, depending on the size and composition of the organism. Various insects, such as ants, earthworms, woodlice, and dung beetles, as well as a host of microbes and other organisms play a part in the decomposition process.
The name of the game here is recycling to return material back to the food chain where it can be used to sustain other organisms, such as plants and the organisms that perform the decomposition. Some material may not be decomposed fully however. ; for example coal is a fossil fuel formed in swamp ecosystems where plant remains were saved by water and mud from oxidization and biodegradation.
The mineralization of the remains of an organization, a process which prevents further decomposition. Normally the hard parts of an organisms, such as shells, teeth, and bones, are the more likely to be preserved long enough so that they eventually fossilize. However, soft parts of organisms may also be fossilized, but this is rarer. Fossils are the mineralized remains or traces (such as footprints) of animals, plants, and other organisms. Fossils may vary in size from microscopic to gigantic, such as dinosaurs.
Conversion to Oil, Coal, etc: Fossil fuels, such as coal and oil, are believed to have been formed over millions of years in swamp ecosystems, where plant and animal remains are preserved against total decomposition by water and mud.
The remains of organisms may also be preserved more or less in tact by various methods, such as freezing. Natural examples include the freezing of Wooly Mammoths in Siberian permafrost for many 10's of thousands of years.
Throughout history, it has been difficult to define the exact moment of death or even define the exact signs and symptoms of death.
For example, death was once defined as the cessation of heartbeat and of breathing. This state is now called Clinical Death.
However, the development of Cardiopulmonary Resuscitation (CPR) and defibrillation techniques have rendered this definition incorrect because breathing and heartbeat can sometimes be restarted. Also, situations which caused death in the past may no longer kill in all circumstances, and this has made it difficult to determine whether a person is really dead or whether they might be able to survive. For example, life support devices, organ transplants, artificial pacemakers, and related technologies can help a person to survive even without a functioning heart and lungs.
Today, people are considered dead when the electrical activity in their brain completely and permanently ceases. This is also called Brain Death and Biological Death. During coma and sleep, electrical activity in the brain may decrease, but it is still measurable. After death, electrical activity in the brain ceases completely.
However, there is currently debate as to how much of the brain needs to be devoid of electrical activity before death can be pronounced. Some doctors argue that the lack of electrical activity in the Neo-Cortex of the brain is a sure sign of death.
However at the current time, most countries define death as the irreversible cessation of electrical activity in the whole brain rather than just the Neo-Cortex. This wider definition can cause complications because the determination of brain death that is, the cessation of electrical activity - can be complicated. For example, Electroencephalography (EEG) can sometimes detect spurious electrical impulses in the brain even after apparent death. In addition, various drugs, hypoglycemia, hypoxia, and hypothermia can suppress or even stop brain activity on a temporary basis.
Skull Image: Todd Huffman / Creative Commons Attribution License