Buffer Problem

Ok, I'm studying acid and base buffers at the moment. What I can't understand is that, with an acid buffer (e.g. sodium ethanoate and ethanoic acid), why does the base react only with the undissociated acid (i.e. the ethanoic acid)? If the base was a strong base (e.g. sodium hydroxide, wouldn't it dissociate in the water readily, causing the OH- ions to react with the small amount of H+ ions created from the dissociated ethanoic acid (I know this is quite small, but wouldn't it still count)?

/sci/, lend me your cognitive thought!