The respiratory system

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Across
  1. 3. something path that can help prevent infections from taking hold.
  2. 6. something passages that connect the alveoli to the bronchus.
  3. 7. something transport gas.
Down
  1. 1. Something that protects the lungs, the heart, etc
  2. 2. sommething make gas exchange, carbon dioxide and oxygen exchange with each other
  3. 4. It powers the flow of blood.
  4. 5. something helps lungs and breathing