how come the members on the bridge of the enterprise never had to use the bathroom?

Gives a whole new meaning to "To go where no one has gone before", doesn't it?

Since the shows weren't completely focused on the bridge, they had more off-screen time to go to the bathroom than Jack Bauer does on 24. :-) Even if they worked 12 hr shifts instead of 8, they also would have had to "hold it" for less time than he does - if he doesn't find a bathroom during the commercial breaks like we do. :-)

I wonder - they probably got lunch breaks during their shifts at some point, and here and now it's a custom to give a 15 minute break per 4hrs of labor (not that some employers actually do that, and there have been some really bad/busy situations I've been in where I did work non-stop on my feet with no break for the first 8 hrs of a 10 hr shift) (I don't work there anymore!), so it's possible there was a bathroom near the mess hall, or whatever it was called on whichever Enterprise you're referring to.

I don't remember seeing another door off of the ready room that would have led to a bathroom... that's something to look for, I guess. LOL!

When the camera's were off they took turns sitting on the captains throne in the middle of the room.

They had cups under the control panels. Or maybe Data had some freaky attachment. Besides, how boring would it be to watch some ensign ask to go to the latrine.

Androids

Actually they tagged in and out but where were the bathrooms?

They never showed where they were but the captain had his own.

How many shows actually show people going to the bathroom??? EVERYONE goes to the bathroom, the tv doesn't have to show it for us to know this!

Good question

one word - catheter!