Where does the exchange of carbon dioxide and oxygen with the blood occur

Question

the bronchi

bronchiole

alveolar ducts

alveolar sacs

It seems that you are asking different questions under different names. You can ask more than one question on a post.

Think of it as transportation. Where does the "end of the line" occur?

If that doesn't help, try

http://www.answers.com/topic/air-sac

I hope this helps. Thanks for asking.