The Respiratory System

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Across
  1. 5. the large sheet of muscle beneath our lungs
  2. 7. narrow tubes that carry air within the lungs
  3. 8. the bones around our lungs which act to protect
  4. 9. two large spongy organs in the breathing system
  5. 11. tube that carries air into the lungs
  6. 12. to breathe out
  7. 13. a gas that makes up 21% of air
Down
  1. 1. air sacs at the end of bronchioles involved in gaseous exchange
  2. 2. to breathe in
  3. 3. commonly known as the windpipe
  4. 4. tiny blood vessels wrapped around the alveoli
  5. 6. another name for the respiratory system
  6. 10. a gas that makes up 78% of air