Respiratory system

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Across
  1. 4. a dome shaped muscle;plays a big role in breathing
  2. 7. tiny blood containing structures
  3. 8. a muscular tube that runs behind the windpipe
Down
  1. 1. the two main organs in which respiration occurs
  2. 2. an organ that is called the voice box
  3. 3. a connected system of hollow cavities in the skull
  4. 5. the windpipe which starts at the larynx
  5. 6. a set of 12 paired bones which form a protective cage