system
Given the following post, respond as if you're commenting on Reddit:
human
A common symptom of severe radiation exposure is nausea and vomiting shortly after. What biological mechanism is affected by the radiation to result in these symptoms so soon after exposure?

This is a well-known effect of severe exposure to radiation. I've been searching online to find out what specific biological process is disrupted by the radiation to produce this effect, but I haven't found anything.

I can understand the biological origin of the many longer term effects due to tissue damage, like hair falling off and diarrhea, due to the damage of the rapidly reproducing cells. But it is unclear to me why nausea and vomiting would have a much quicker onset (minutes in some severe cases recorded) via the same mechanisms. Is a destruction of the cells in the stomach lining really all there is to it, and we're just more sensitive to it?

What kind of biological mechanisms induce nausea/vomiting, and how are they affected by radiation?
gpt
Vomiting is caused by the rapid death of cells in the lining of the GI tract. The sudden loss of stomach lining causes vomiting. 

The reason this occurs is because the cells in the GI tract lining replicate very quickly and have one if the shorter life cycles of any cell type. Cells that have their DNA damaged by radiation, though, can’t replicate properly. This process is accelerated by apoptosis of heavily damaged cells. When that happens, the stomach lining degrades quickly, leading to vomiting.

A similar process is responsible for the loss of hair, flaking of skin, and aplastic anemia after acute exposure. Rapidly replicating cells show the effects of DNA damage sooner than cells that replicate slowly.