Penis and testicles
We tend to take peeing for granted. Something easy is described as 'a piece of piss'. But it's not such a simple business. Sometimes it happens when you don't want it to. Other times you can't go even when your bladder's bursting.
Peyronie's disease is a condition where your penis becomes more bent than usual.
Incontinence - leaking pee without meaning to - is a wee problem that can be treated, reports Danny Farthing.
Kieran Brennan had an NHS vasectomy in Scotland in March 2009. This is his post-vasectomy diary.