How is it that the body survives for weeks or months before finally succumbing to death after a lethal full body dose of radiation poisoning? I’ve heard that the penatrating radiation of gamma rays and neutrons destroy the DNA beyond repair. So how does the body continue to function for so long afterwards before finally losing the battle? How do cells without DNA carry on?
In: Biology
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Because the thing that kills you isn’t that it instantly kills all of your cells.
It’s that by destroying your DNA, it destroys your cells’ ability to repair themselves and multiply.
So say your kidneys get irradiated, they don’t just instantly die. They keep working for a while. But as more and more cells die or get damaged naturally, those cells cannot be replaced like normal, which means your kidneys start working worse and worse until they totally fail
The reason is that the damage is directly to your DNA, and DNA is not used in the regular functioning of your cells.
DNA is read to make more proteins that are needed, which is a very long process that takes hours. So the earliest you would possibly experience an effect would be after several hours, at which point the cell would just have a low amount of protein synthesis, and eventually that builds up and causes death of individual cells.
Eventually those dead cells can’t be replaced, and that’s what causes dysfunction and possibly death of the whole organism.
But if you were to magically teleport all the DNA out of your body, you would continue functioning for hours if not days, or maybe even a week, I’m not wholly sure exactly how long.
It’s kind of like driving a car that suddenly catches a type of fire that won’t go out: it’ll keep going for a little bit as before but will totally break down soon.
Lethal acute radiation poisoning is basically “Children Of Men” for your cells. They’re still functional, mostly, but as they reach the end of their lifespans there’s no next generation replacing them
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The LD 50/60 Dose is the dose that if exposed to will result in 50% of a population dying in 60 days without medical intervention. Just to give a number that’s roughly 400 rad. Death if it occurs at this point is generally from hematopoietic syndrome, which is basically where the blood forming tissues(bone marrow) are killed/damaged and your body cannot effectively replenish blood cells that die off naturally and you can eventually die from that, this could take couple months.
Around 1000 rad gastrointestinal syndrome becomes major concern, your GI tract is basically killed, and you can no longer absorb nutrients from food via your intestines and either starve to death, or die of infection as your intestines break down, killing in a week or two, death is effectively guranteed even with medical help.
Central nervous system syndrome starts to occur around couple thousand RAD and kills in a few days as your nervous and circulatory systems basically fall apart, if your lucky you’ll be unconscious that whole time.
While some cells will die outright from radiation exposure, most that die will die when trying to replicate and create new copies of themselves (or derivative cells).
The main thing that kills a human from radiation exposure is damage to fast replicating cells (which are both more vulnerable to radiation and more quickly affected).
Mainly this impacts two types of cells. One of these cells are the ones in the intestinal lining (that allow us to keep eating), which is one of the big reasons why radiation sickness leads to nausea, vomiting, intestinal bleeding etc.
The other type of cell are the bone marrow cells that create red and white blood cells (they keep replicating, some of the replicating cells stay stemcells to create the next generation, some transform into white or red blood cells). White blood cells are important to the immune system, so radiation sickness leads to increased vulnerability to infection.
**The ticking timebomb are the red blood cells**. Red blood cells function for 120 days (give or take) and they’re responsible for providing oxygen to the body’s cells (and if they don’t get oxygen, then they die). Which means that from the second someone gets exposed to radiation sickness their red blood cell count starts to deplete, and it’s going to hit its critical low point after 100-120 days. To massively simplify the issue. If the victim has enough bone marrow left alive to keep their red blood cells at a survivable level as that clock runs down, then he lives. If he doesn’t, he dies.
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