Check out this realistic animation of the action at cellular level – amazing to think this is happening inside you right now. It was produced by scientists at Harvard in 2007, as part of a project called ‘Biovisions‘.
Here’s an embedded YouTube version, but do visit the actual site for a better resolution and more info:
EDIT: The video was removed from YouTube. So just go and visit the site, link above (there are other videos now) … you won’t be disappointed.