- [voiceover] let me takeyou back to that time period, about four to six hoursafter an infarction when the blood-brain barrier was just starting to break down, because i want to talk aboutsomething that's happening in the ischemic area of thebrain here around that time. and that something is inflammation. there's an inflammatoryreaction to the stroke going on here as well. and just as a little reminder, an inflammatory response is sort of a protective biologicalresponse of tissues. it happens whenever really anything sort of irritates your tissues. so, you know, right now we'retalking about something big, like inflammation after a stroke. but, you know, you'd even getsome inflammation happening when, oh, i don't know, say you get a little scratch from your kitty. so you might notice that evenif the skin isn't broken, you'd see some swelling and redness over the scratched area. and that's some inflammation happening. and you even get aninflammatory respon...