system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: how does breaking someone's neck supposedly kill them immediately?
gpt
When your neck breaks near your skull, three things happen - you can't move, you stop breathing, and your body loses the ability to control your heart. While you're not technically dead *yet*, you're close enough to it (the action/kung fu movie trope of a person slumping lifelessly to the ground), and *will* be dead shortly thereafter without medical attention.

It basically happens because the 'wire' (spinal cord) that runs from your brain to the rest of your body, that tells it to move and keep living, is severed.