Respiratory System Crossword

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Across
  1. 2. When your muscles do more work, they _____________ oxygen.(2 words)
  2. 3. Your body cells need _______ to work.
  3. 5. transfer to your bloodstream
  4. 7. You release this gas when you exhale. (2 words)
  5. 8. This is also known as the windpipe
  6. 9. Tiny air sacs
Down
  1. 1. Tubes look like _________ on a tree.
  2. 4. Your body _______ store oxygen.
  3. 6. protects your lungs
  4. 10. The main organs of the respiratory system