What causes the urge to urinate?

So, if you insert a catheter, inflate the ballon then hang a weight on the catheter will the pull against the bladder or pressure on the sphincter cause that urge? The greater the weight the more the urge?

Ladies with a short and downward oriented urethra would be more affected, I would think.

I certainly don’t advocate trying this. Just my imagination posing a hypothetical and kinky procedure. I may be deviant 😛

The bladder is a large muscle. When it gets full it stretches and gives you the urge to urinate. Over stretching can cause pain and weakness.