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Across 1. Muscles which move the ribs 3. A muscular sheet used in breathing 5. Found at the first branch of the respiratory system 6. Becomes stickier when infected by bacteria 9. A tube connecting the mouth and nose to the rest of the respiratory system 13. Excreted through the lungs (2 Words) 14. Occurs at the surface of the alveoli (2 Words) 15. Damaged by tobacco smoke; not waving anymore 16. Found at the end of the respiratory tree 17. Smokers become addicted to it 18. A disease which affects the alveoli

Down 2. Contains over 5000 chemicals (2 Words) 4. To do with the lungs, eg a membrane 7. Taking air into and out of the lungs 8. The gas which makes up most of the air 10. Obtaining energy from sugar in every cell in the body 11. The normal flow of air in and out of the lungs (2 Words) 12. Progressively smaller tubes found in the lungs