Why can't our body resist radiation?

because effects of radiation include nausea, hair loss, and dry mouth. other side effects include muscle soreness, dry skin, and fatigue #believe

Our body construction and components (Cells, bones, even the blood) is already resisting radiation. What I mean is that every day, we are exposed to radiation, so our body does resist radiation, but all has a limit, so if we overcome that limit, we might suffer deep injuries and even death.

In resume, we do resist radiation, but no high level exposition.