Across
- 4. what you breathe out
- 8. air sacs exchange oxygen with CO2 in blood
- 9. small air tubes connect bronchus to alveoli
- 10. What you breathe with
- 11. end of the trachea splits the air into each
- 12. what you breathe in
Down
- 1. high to low concentration
- 2. tiny blood vessels that transport blood
- 3. an organ that collects air
- 5. inflating and deflating the lungs
- 6. a pipe that sends air to the lungs
- 7. surrounds lungs