Respiratory system

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Across
  1. 3. organ for the exchange of gas between blood and the atmosphere
  2. 5. an air-filled space above and behind the nose
  3. 6. the two tubes branching to the lungs
  4. 7. the tube that filters air before it enters the lungs
  5. 9. the amount of air that can fill lungs
  6. 10. the oxygen-carrying protein found in red blood cells
Down
  1. 1. a bubble-like sac in the lungs where gasses are exchanged
  2. 2. the part of the throat below the mouth and nasal cavity
  3. 4. the smallest blood vessels
  4. 6. the passageway where air flows to an alveolus
  5. 8. the flap that keeps food out of the lungs by shutting in front of the esophagus