Across
- 4. chemical from cigarette smoke that makes lungs black
- 7. many air sacs
- 8. makes up less than 0.04% of the air
- 10. one air sac
- 13. when blood swaps carbon dioxide for oxygen
- 15. gas that makes up most of the air
- 17. large tube entering a lung
- 18. sheet of muscle moves downwards to breathe in
Down
- 1. rings of this keep the trachea open
- 2. is an addictive ingredient in cigarettes
- 3. small branching tubes
- 5. means to breathe in, to take one breath
- 6. small blood vessels surround the alveoli
- 8. small hairs that sweep mucus up & out of the lungs
- 9. makes up 21% of the air we breathe in
- 11. traps bacteria and dust that we breathe in
- 12. causes lung tumours or lung cancer
- 14. carries air to and from the lungs
- 16. when the lungs are ventilated with air