The Respiratory System Crossword Puzzle

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Across
  1. 1. The name for the top of the lungs
  2. 6. The protein found in red blood cells
  3. 7. The main organ of the respiratory system
  4. 8. What filter microparticles out of the nasal cavity?
Down
  1. 2. The flap that covers the larynx
  2. 3. Where does external gas exchange occur?
  3. 4. What is the common name for altitude sickness?
  4. 5. What do fish use for gas exchange?