Watering eyes and nose hairs

Will someone please tell me why your eyes water when you pluck out a nose hair? I really want to know. I've searched online for about 30 minutes and come up dry. I'm looking for a medical reason; I'm really curious. I would also like to know why your nose runs when it's cold outside. I'm completely serious. I even tried looking through medical journals online to find out why with no luck.

In case you guys were wondering what I'm thinking about when I look like I'm deep in thought, it's this kind of stuff. Sorry to disappoint.