Across
- 4. Windpipe that connects the throat to the lungs.
- 6. Main organs of the respiratory system.
- 8. Muscle that helps lungs expand during breathing
- 9. Gas needed for cellular respiration.
Down
- 1. Tiny air sacs where gas exchange occurs.
- 2. Voice box, located at the top of the trachea.
- 3. Substance that moistens and protects the respiratory passages.
- 5. Membranes surrounding the lungs.
- 7. Two main air passages into the lungs