It is hard for me to imagine that when a person dies all the cells in his body die at the same time, in other words, is death instantaneous? After all a part of our body can die and we can still be live, so it is likely that a part of our body can still be alive for a little bit longer, until the lack of supply of oxygen kills it. If someone dies of sickness or violently, it is easy to imagine that a crucial life function has stopped and thus his body dies. But what do we mean by the expression natural death? Some crucial part of our body has to go kaput, and if it does then that is some sort of sickness isn't it? Do we mean undiagnosed sickness when we talk of natural death or is it something else? Can I fool a part of my body by supplying false information to remain alive? Or is there some sort of PSI wave that goes through the body and tells all parts to switch off at the same time? Or is it that when the metabolism that supplies oxygen and food dies the rest of the body just dies along with it.

Well, I dis attempt to answer a similar question, while i was writinfg for a regular column "Curiosity Corner" in Science Reporter magazine, some nine years ago. Here is my answer that I wrote then



The full article is still available @ http://www.scribd.com/doc/1016/Life-from-Birth-to-Death

in addition to what hallen sir wrote
it is not definitely so, becoz that is why eye donation, heart donation and other body part's donation is possible.

well, a nice question put up by tarun....

doctors declare any person dead if his brain and heart both stop working, sometimes brain dies temporarily (coma), and sometmes heart does, bt 2 declare a person totally dead both th parameters as to be checked...

& 1 question, very old.,.... how ingestion of cyanide even a drop can kill sm1 in a matter of second...
1 thng can b bcos cyanide is an inhibitor of ETC, bt that would take time, bt a person dies within a second!!!! any1???

& yes 1 more thing, cyanide is found in bamboo, & panda ets much cyanide through it, then hw cn it remain alive??? i read it few years back in a newspaper that they eat sufficient cyanide through bamboo...!!!

so is it only in the case of human???

Cyanide competes with oxygen as the final electron acceptor in the
electron transport chain. Without oxygen the body cannot complete cellularrespiration which makes energy available to the body.

Further it is a misconception that death occurs within a few seconds after ingestion of cyanide. For example look at the following link which states:



http://www.fas.org/nuke/guide/usa/doctrine/army/mmcch/Cyanide.htm

one possible guess is that they have better cyanide biotransformation pathways.
Biotransformation is the chemical modification (or modifications) made by an organism on a chemical compound so as to render it less toxic.
Biotransformation
humans have Rhodanese enzyme that converts the cyanide to less toxic thiocyanate.
Probably the Pandas have even better Rhodanese enzyme.

Start reading from page 474 Cyanide metabolism
cyanide metabolism

while searching i came across other possiblities also
http://www3.interscience.wiley.com/cgi-bin/summary/114802885/SUMMARY?CRETRY=1&SRETRY=0

Consider an analogy with a machine. A machine can become non-functional even if only one critical component breaks down. If a minor component breaks then the machine can sometimes continue working with reduced efficiency. In case of a machine if we replace faulty components then we can start the machine again.

The real question is, why is it that we cannot restart functioning of a human body by replacing faulty components. Faulty parts of human body are now replaced routinely, but this is typically done while the person in question is still living.

It appears that in case of humans, there is a time after which it is impossible to revive the body functioning. One issue that may be relevant is that in a living being, the body has to fight off attacks by bacteria, fungus and virus. After some time, in case of body functioning stopping, degeneration of tissue may make auto repair impossible and there will be too many organs to be repaired to breath life into the system again. Perhaps one of the biologists, or accomplished googlers can pitch in with more detailed input on this.

Jasjeet

I think hallenrm's first post and lakshy's clarification basically answered the first part of the question. Though I am still not entirely clear about what do we mean by natural death.



That's an excellent point! So when a cell or an organ dies something irreversible happens inside it! I think if we could somehow achieve this it would bring about the death of the life-spirit idea. This is perhaps the only reason that living beings are thought to be different from machines. Does anyone know what is this irreversible event that makes it difficult/impossible to bring a dead thing back to life?


Yeah, I too would like to know a good answer to what Jasjeet has posed here.

with in limited span of time (as there is no electricity and its working on UPS) i can say only that "suppose if came to know about that certain set of genes get activated with advance ages that produce some sort of signals that induces greater rate of apoptosis in the body than compared to under normal cicumstances, Iaam not putting stress over this that there is genetic cause of natural death but iam putting forwrd a possibility. That gene might get activated in years due exposures (some certain kind of exposures) to some agents".

at the outset let me make my position clear, I am no biologist, and to post this reply i am not as usual taking recourse to googling. Jasjeet comment, reminds me of my brief crush with theoretical biology while i was pursuing for a Ph.D degree. I even attempted to get admission in the graduate program of Department of theoretical biology at SUNYAB, with my application i sent this idea. As far as i can remember, the idea was as follows:

Death is a phenomenon largely limited to multicellular organisms, many unicellular organisms arebiologically immortal So, one has to keep this factor in mind while attempting to offer an explanation. The cells in a multicellular organism are periodically replaced, because some cells in its body die regularly. The death of these cells may lead to the accumulation of cell debris within the system. Since most of the constituents of these debris are not foreign molecules they are assimilated by the living cells of the body that make up its superstructure, but this assimilation leads to decrease in strength of the tissue/organ to fight invasion by foreign bodies. Thus, in fact we die every moment of our life. Death therefore is not a momentary event save the case when it is due to some fatal injury or failure of a crucial body organ; it is result of many more biological processes that occur in our live body. That is what we call aging

That leads to yet another very interesting question: Why do some cells in multicellular organisms die?

Death can be instantaneous but its not necessary that all cell die intantaneously when a person dies. Death is ceasation of all vital process in the organism that supports life.

Of course! as already stated by Lakshy.

An organism remain in the living state because its metabolism provides energy to do work and makes the system (organism in concern) to maintain a dynamic steady state which is far from equlibrium,
http://csecduac.in/viewtopic.php?t=655

By maintaining a steady state of an organism (open system) we mean, a system in which the rate of input of energy and matter is more than dissipiation of energy and the output of materials, and this is maintained at the normal rate (approximately constant for a given species).
maintaining a steady state requires a constant input of energy from surrounding.And when a cell can no longer can generate energy it dies and begins to decay toward equilibrium with its surrounding, and free energy change at equlibrium is zero. That means no energy in its usable form is available to do work and to over come the entropy.
In biological system an increasing degree of entropy results in death of a cell or the organism, unless the energy is restored.
Usually energy is restored through the input of free energy. A free energy is that portion of total energy of the system which is available for doing work.
so death appears due to increasing entropy of the system and destruction of steady state that is being at the equilibrium with surrounding.

But at this point an important point from the question posted by Tarun sir arises, that is

If everything is going normal then what went wrong that caused the ceasation of the vitality of the body?
Death is often taken as an outcome of aging and the process of aging may be defines as the progressive deterioration in structures and function of the cells, tissues, organs, or organisms with advancing age.
There are many theories that account for aging, I mean how it occurs and its causes.

Aging leads to the weakening of body tissues and of vital organs causes reduction in the efficiency of body to produce energy or free energy. Gradually the body becomes inefficient for producing energy (free energy) to over come the entropy of surrounding and this event is called DEATH.

To this ramanand has posted a possible answer as:



But, there can be yet another reason that i have discovered just now on the sciam site. It is inresponse to a query: Why does programmed cell death, or apoptosis, occur? Does it take place among bacteria and fungi or only in the cells of higher organisms? To which Michael Hengartner, senior staff investigator at Cold Spring Harbor Laboratory, offered an answer as follows:

Besides the biological criterion there are several philosophical underpinning to the concept of death. For example read the following section of an article published at the Stanford University website:

well I don't agree to this point given by hallen sir, because we have number of mechanism to get rid off of the cellular debris, like wandering phagocytic cells.
They take up the cellular remains and digest them rather making their super structures. Upon digestion their proteins are displayed over the cell membrane of these phagocytes, as these proteins come from the normal turn over of the body's own cell this donot leads to activation of the immune system. But when these wandering phagocytes engulfs some foreign proteins or cell, upon their fragmentation to small peptides they display them to their cell membrane for the activation of the immune system and removes that pathogen (or antigen) completely.


But one of the most important thing that we have not discussed till yet is

I doubt if this system is absolutely perfect

350 million erythrocytes produced every min, means approximately equal number is being replaced, ours system is really efficient enough to remove all these debris from our body.
But one thing still remains the same

[/quote]

one should not forget no system is 100% efficient (at least i belive so),
furthermore, efficiency wil decrease as one age.

Simply saying that ours system is really efficient enough to remove all these debris from our body, is not sufficient argument in this case, can you cite some reference to support your claim

Sure sir.
but I want some time to search and fimd some appropriate links.

i m going to talk about "aging" and not "death" but surely the former leads to the latter.
rather than just thinking that RBC debris are not removed, plz note that there are changes that occur in one's genome that are not removed (means that they accumulate as one ages), and when these changes occur in the "vital" genes, the body wil show inefficiency (this is just one theory of aging).
and lets assume if such changes occur in phagocytes then there function will be compromised and rest of the story u can build urself.....

http://www.sgul.ac.uk/depts/immunology/~dash/apoptosis/



These mechanisms shows how simultaneous and co-ordinated changes occur in the system to remove the waste from the body. When a cell begins to die the entropy over comes the free energy state of that cell (in case of apoptosis) and some morphological as well as chemical changes occur in the cell to facilitate its own phagocytosis.