Put a tear in my eye.. why?

I spent the weekend in Oxford, which is 2 hours drive from where I live. We had good music with us, so we didn’t mind when we went on the wrong motorway and the drive back actually took us twice the time… we talked about this and that and at some point a friend of mine said that he hadn’t cried since he was a child.

Last week I had a bicycle accident and I had a bad shock. I got really confused and my shorttime memory went, which is when I realized my face was wet… Why do we cry?
Surely it is some kind of pressure relieve, but there must be a physical reason? Why do our eyes water when we get hurt, or are in shock, or are simply sad?

Biology student anybody?

Just wondering,

I’d like to second the question. Why do we cry when the environment doesn’t call for it?

One reason we cry is to help wash contaminants out of our eyes. This explains having a runny face when chopping onions, getting a faceful of smoke, or the like. What I (and BornDodgy) can’t figure out is why the tears flow when there’s no physical irritant present.

(WAG Alert: If exposed, take one grain of salt and seek medical attention)
I suspect that the emotional states involved in crying flood the bloodstream and nervous system with the same chemicals as in allergies; histamine, in particular, has been implicated in stress states. Sorry I don’t have any good links, but the research is kind of spotty on this issue, and lots of the sites I could find actually dealt with Irritable Bowel Syndrome…