Respiratory system

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Across
  1. 3. dome shaped muscle that helps to breathe
  2. 4. oxygen passes to blood though these
Down
  1. 1. the smaller branches of the bronchial airways
  2. 2. Also called the windpipe
  3. 5. the organs that are used to breathe
  4. 6. To breathe out
  5. 7. To breathe in