Irrationality/rationality of Pain

What is pain, why do we feel it, and when we do feel it, why the hell do we yell?

we all know the first answer, its our body's neurological message to us to say hey something is wrong here, pay attention to me. but why does the body continue to hurt with injuries that you can't do much about other than watch them heal themselves? Why not just an instant feeling, then it fades away once the message has gotten into your head.

That part I don't mind, but the real issue is why do we yell when we feel pain, why does it incapacitate us from doing anything else at the moment. distract us, midstep, from anything...except I suppose if you were in a fight. Maybe that's what it takes to get stupid humans like ourselves to pay attention to the problem. otherwise we'de just dismiss it and continue to aggravate it.

but the yell from pain still doesn't make sense.... do we really need something that dramatic to catch our attention to where we can't do anything except let out a helpless yell? I supopse if we didn't feel pain, we'de torture ourselves and in some wacky way enjoy it. The body's self defense system against itself.

enough rambling... time for work