Well i don't usually hunt from a tree stand, but biologically we are both mammals and besides a few differences we all go through the same process or urinating. ie the stuff coming out of you and the deer are fairly the same, so there should be no problem at all peeing from your tree stand...doing the #2 however does have its differences....lol
But using that same logic, why do we as hunter address the oder issue so much? Why do some wear rubber boots and scent loc suits?