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Across 1. the throat 7. the exchange of oxygen and carbon dioxide between teh lungs and blood-stream 9. what the trachea divides into 11. filters inhaled air that traps dust and other particles 14. where air is held 15. a special leaflike piece of cartilage, closes the opening into the larynx during swallowing. 16. (inhalation) the process of breathing in air. 17. consists of the lungs and air passages 18. a tube extending fron the larynx to the center of the chest 19. the process of inspiration and expiration 20. has two openings, called nostrils or nares, through which air enters

Down 2. divides the nose into two hollow spaces 3. the lung is enclosed in this, a membrane or sac 4. the process of breathing 5. when cells use the oxygen and nutrients to produce energy, water, and carbon dioxide 6. cavities in the skull that surround the nasal area. 7. (exhalation) the process of air being forced out of the lungs and air passages 8. the exchange of carbon dioxide and oxygen between the tissue cells and blood-stream 10. the two hollow spaces divided by the nasal septum 12. smaller branches off of the bronchi 13. allows oxygen and carbon dioxide to be exchanged between the blood and lungs