[DaBackpack]

Yeah professors generally don't care if you up and go to the restroom, you're just responsible for anything they say while you're out. When I was lecturing I straight-up don't give a shit; if during recitation or office hours, I personally never cared and understood that Everyone Poops™ but some might? idk

Same with work, I think people generally understand that relieving yourself is a good thing. The biggest counterexample is if you are currently delivering a business presentation or lecture, or if you are in a phone call or small-scale meeting room. These are all prescheduled events so... "you should have gone before the scheduled time" is what most people'd say.

EDIT: "Please excuse me for a few minutes" or "I'll be right back" are perfectly fine euphemisms.