respiratory system

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Across
  1. 4. tubes leading from the trachea to inside the lungs
  2. 5. process in alveoli, where the air exchanges carbon dioxide and oxygen with blood through diffusion
  3. 6. houses the vocal cords
  4. 7. moistens tissue and filters air
  5. 9. also known as throat first place air enters through the nose and mouth
Down
  1. 1. sacs where air ends up, exchanging oxygen with the blood
  2. 2. small tubes leading into the alveoli
  3. 3. main muscle of respiration that causes lungs to expand and contract
  4. 8. hair-like structure protecting bronchi