system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What causes the "ache" in a stomach ache?

Not "what causes a stomach ache", but more of: what's happening in your stomach and why does your body respond the way it does?
Please and thank you.
gpt
The short answer is that there are specific neurons (cells of the nervous system) that line the stomach, and their job is to generate pain signals when something is wrong. So when you have a stomach ache, these pain-neurons become active and send signals all the way to the brain which then allows you to become conscious of the pain.