Do you know the difference between respiration, breathing and gas exchange?
You will, hopefully, by the end of the next topic. Here are some resources to help you. This one gives basic factual information. This one is interactive. And this one from Get Body Smart is also good.
Watch this excellent video from TEDMED where Dr Keshavjee brings a breathing lung on stage!
This one, about a smoking 2 year old, is much more disturbing to watch! Again, thanks to Mr Taylor over at iBiology for finding the resource.