Across
- 1. middle of the heart
- 5. voice box
- 6. gates in the heart to allow blood flow
- 7. small blood vessels that carry oxygen
- 10. air rushes in because pressure in chest is low
- 12. bones protecting the lungs
Down
- 2. the oesophagus of the lungs
- 3. main artery
- 4. air rushes out because of increase of pressure
- 8. blood vessels that lead away from the heart
- 9. the organs for breathing
- 11. small sacs covered in capillaries
- 13. branches that come off the trachea