It depends what ‘happened’. If something got into our blood for example, our heart, liver and kidneys may be more effected whereas our brain may be okay as the blood is filtered in getting to the brain by the blood-brain barrier. if we are in a fire, our lungs and skin are at the most immediate risk. If we are in a car crash, possibly our brain could be most in danger as the crash can rattle the brain in the skull.
If you have a particular example in mind, send me a new message and i’ll try to answer it 🙂