system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5 What exactly happens to the brain/body when someone gets hit so hard that they’re knocked unconscious? Why does this occur?
gpt
We're not entirely certain about why you lose consciousness from a knockout blow, we think it has something to do with the force of the blow cutting off blood flow to the brain or compression of the brain stem. We know that professional boxers building up their shoulder/neck muscles somehow allows them to sustain harder blows to the head without being knocked out, we also know most knockouts come from a uppercut/jab to the jaw that causes the head to whip around quickly.

Sorry this isn't the best answer, but most of it is still speculation. We can't exactly put someone in an fMRI then hit them really hard in the head.