I’m sure all hell starts breaking loose once the oxygen stops flowing, but still, it’s not instantaneous. Google didn’t help me. Are we talking hours or days?
INADoctor, but I understand that brain cells start dying within a few minutes of no oxygen. Other cells with lower metabolic requirements might hang on longer, but I don’t think we’re talking hours in any case.
If we’re taking the definition of cells that are “alive” to be able to be practicably revived through restored perfusion (rather than for example merely ongoing biochemical processes), muscle and other tissues can “live” for hours without perfusion (delivery of oxygen and other nutrients).
“Recommended ischemia times for reliable success with replantation are 12 hours of warm and 24 hours of cold ischemia for digits and 6 hours of warm and 12 hours of cold ischemia for major replants, although successful replantation has been reported after longer ischemia times.”
I guess this an effort to see how long you remain “aware” in some sense of the word. Would the immediate effect be that of falling asleep. Would the brain attempt to do whatever it normally would do if one fell asleep; would it try to go through normal sleep cycling as long as it could. Or would oxygen deprivation immediatley render that process impossible.
I don’t think that sleep and brain ischemia are at all comparable. Your blood flow is realtively normal or even increased throughout sleep, the brain has certain distinctive patterns of activation but even that isn’t significantly less metabolically demanding than being awake. Sleep probably requires at least 75-80% of the oxygen that waking does, and REM sleep might even require more oxygen than when someone is awake.
A loss of consciousness occurs even more quickly than the neuronal cell death referred to up-thread. We’re talking on a 30 second to one minute time-scale.
I would guess that brain death is more akin to fainting or being knocked out than going to sleep.
Your individual brain cells may survive for several minutes after blood flow stops, but consciousness seems to be a much more delicate process; once you stop getting oxygen to the brain, you lose consciousness in 10-15 seconds, and as far as we can tell you don’t experience any dreams or sense of time passage unless blood flow is restored in time to survive. Of course, if blood flow is restored, then you can experience all kinds of weird dreams and hallucinations before you actually regain full consciousness.
If your name is Henrietta Lacks then you’d have cells that have survived 57 years after your death and are still going strong.
Quite a long time, in some cases.
Szlater, get out of my head. Now.
Technically dead or just non-responsive to stimuli?
On the killing chain, the muscles of the head were still twitching over an hour after the bulls had been slaughtered - the heads had been disconnected from the bodies at least 45 minutes. Cows and steers didn’t seem to last as long.
It was part of the processing to run an electrical current through *all *the carcases (mutton too) just before they were frozen. This would be up to two hours after slaughter and it was done because the muscles would tense in reaction to the shock - depending on who you asked, either for a firmer cut of meat or because they could fit more bodies into the freezer. These were fully processed carcases, skinned, gutted, headless and hoofless, but the muscle cells still reacted to stimuli.
Old thread: [thread=415222]What is the relationship between physical death and cell death?[/thread]
Stranger
<baffled>
Enhance, please?
Read Derleth’s link.