That knot in your throat

This thread probably won’t last 5 seconds, this seems like a question that has surely been asked before but after a search of SD I found nothing.
What is physically going on when you get that knot in your throat at an emotional moment? I watched saving private ryan last night and got one at the end…it was uncomfortable if not downright painful.


“I think it speaks to the duality of man sir.”
(private Joker in Full Metal Jacket)