The Respiratory System

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Across
  1. 4. what you breathe out
  2. 8. air sacs exchange oxygen with CO2 in blood
  3. 9. small air tubes connect bronchus to alveoli
  4. 10. What you breathe with
  5. 11. end of the trachea splits the air into each
  6. 12. what you breathe in
Down
  1. 1. high to low concentration
  2. 2. tiny blood vessels that transport blood
  3. 3. an organ that collects air
  4. 5. inflating and deflating the lungs
  5. 6. a pipe that sends air to the lungs
  6. 7. surrounds lungs