Fill in the blank

1. The lungs are the main organs  of  the  respiratory  system.    When  you  breathe  in,  you  take  in     ____________  from  the  air.

2. When you breathe out, you get rid of _____________.

The long tube by which air is carried to and from the lungs is called the trachea, or   _____________.

4. What are the two tubes called that lead to the lungs? _________   

5. In each lung, the small tubes that branch off the bronchi are called________.