Death is not an event, but a series of them – a process. The death process can be complex business; sometimes it isn’t even necessarily permanent. Cellular breakdown is reversible days after oxygen delivery has ceased, under the right conditions, and scientists have even restored – temporarily, but successfully – activity in dead brains. Human cells – even whole humans – survive and grow in glass dishes in laboratories… technically “alive”, if not independently viable.
How is “death” defined, then? What criteria need be met for someone to be unrevivable?
Clinical Death (Minutes 1-10)
The boundary between life and death isn’t absolute, even when things don’t look promising – bad car accident? Heavy bleeding, no pulse, no breathing? Amputation, even? No reason to give up quite yet.
When a person has been involved in a traumatic accident or the heart and breathing have stopped for another reason, the primary criteria of “clinical death” have been met; yes, you’re dead at this point… but only sort of. Maybe only for a minute. Clinical death can be, and often is, reversed without serious consequences to the “decedent.”
But if nobody steps into the gap to restore the flow of blood and oxygen, stop bleeding and return the body to homeostasis, clinical death is followed by the more widely recognized, irreversible kind. Without intervention, a person will probably not spontaneously recover (it happens, but don’t expect it).
The brain may survive 4-6 minutes without oxygen but after that point, the “window of survival” slides slowly closed, and the progress of further physiological changes lead directly to decomposition.
Biological Death (Minute 11 – Eternity)
Biological death is the point of no return. Too much goes wrong here, from too many directions at once, to reverse course. What happens to the body at the cellular level, very quickly, very soon after loss of heart function and oxygen delivery, is extreme. It is violent. And it is well that it occurs below the threshold of our native capacity to experience, for it would certainly be horrifying to perceive.
Once oxygen in all systems of the body has been fully depleted and remains so in a sustained state, cellular failure achieves catastrophic proportions. Cells poison themselves. Their membranes burst. They swell with toxins and explode, poisoning their environment and setting off further destructive chemical reactions, like a bomb dropped at the center of a network of gas stations.
The course of events to the point of no return looks something like this:
Minutes 1-2
- The heart stops beating
- Circulation ceases; oxygen delivery stops
Minutes 3-4
- Without circulation, waste products cannot be carried away
- Without oxygen, normal cell function ceases
- Waste caused by chemical reactions builds up inside cells
- Blood pools and begins to settle
Minutes 5-7
- Acidity builds inside the cells as waste accumulates
Minutes 8-10
- The acidic environment causes cell membranes to rupture, releasing enzymes which consume cells from the inside out (autolysis)
- Brain cells self-destruct first
- The liver, rich with enzymes, follows
- The body begins to cool; temp will fall 1.5 degrees Fahrenheit/hour until the body cools to the temperature of the surrounding environment (algor mortis, the “death chill”)
Gradually, and Then Suddenly
Within the first twenty minutes or so, while a fresh body looks harmless enough, does not smell, and is in no way particularly offensive, a holocaust has begun on the microscopic level. Cells are small, so progress, while explosive on the cellular scale, moves rather more quietly and casually from our perspective, but apocalyptic change has been set into motion, and cannot now be turned back.
As with decomposition, a lot of individual and regional variables come into play to affect precise timing of the processes, and while lists like this one can be satisfying to those of us with organizational fetishes, there are no hard-and-fast time limits. But rapid calamity is certain, whatever the timetable.
And yet by minute 1440 (24 hours after clinical death), skin cells may still be harvested, heart valves and corneas are still “alive.” White blood cells may still be going 3 days later. Bittersweet, baffling evidence of life’s endurance in the wake of mortality.
