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
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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