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