system
Given the following post, respond as if you're commenting on Reddit:
human
[ELI5] WHy do you sometimes not feel a cut when you get it?
gpt
Pain really is all in your head in a manner of speaking.

So when a body part is damaged, nerves at the site of injury send signals up to your brain where it is processed and interpreted as pain.

Normally this serves as a warning system to bring our attention to what is being injured so as to prevent it from being injured more.

However for things like very minor injuries (small cuts, bruises and so on) if the brain is already preoccupied with a task, these signals basically get ignored.

The more concentrated you are on the task the more likely you are to ignore the signals.

It's why a lot of the time we won't feel the pain until we actually see the cut, because it's only at that point our focus becomes the injury.