Respiratory system

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Across
  1. 5. We breathe in using a muscle called the?
  2. 6. the tiny air sacs at the ends of the bronchi
  3. 8. one thing our nose helps to filter
  4. 9. what do we breathe in?
Down
  1. 1. what is the name of the system humans use to breathe?
  2. 2. we couldn't talk without it.
  3. 3. carbon dioxide is the name of the waste...?
  4. 4. what is bad for your lungs?
  5. 7. the colour of a healthy lung