Across
- 1. system that includes the lungs, trachea, and bronchi
- 3. tiny air sacs in the lungs that are surrounded by tiny blood vessels
- 6. air passages that are smaller than bronchi
- 7. air passages that lead from the trachea into the lungs
- 8. the gas that enters the bloodstream at the lungs
Down
- 2. windpipe that connects throat to lungs
- 4. system that includes the lungs, trachea, and bronchi
- 5. muscle that controls breathing by contracting and relaxing