Respiratory System

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Across
  1. 2. Muscle that helps you breathe
  2. 4. Tiny air sacs in the lungs
  3. 5. Smallest air passages in the lungs
  4. 7. Organ where gas exchange occurs
Down
  1. 1. Windpipe that carries air to the lungs
  2. 3. Tubes that branch off from the trachea
  3. 6. Gas you breathe in