system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why is it relatively easy to hold it in before you pee, but hard to stop during it?
gpt
The smooth muscle that makes up your bladder isn't under direct conscious control. It works mostly automatically - once it starts draining it will keep going till it's empty unless something stops it. You can stop it using other muscles that are under direct conscious control but it takes a bit of practice and you have to develop those other muscles enough that they are strong enough to effect the bladder.