Respiratory system

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Across
  1. 3. Another name for windpipe.
  2. 4. Tiny air sacs where gas exchange occurs.
  3. 6. Muscle located under the lungs.
  4. 7. The organ that we use to intake oxygen.
Down
  1. 1. Breathing in
  2. 2. Tubes that connect the windpipe and lungs.
  3. 5. Breaking out