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