Across
- 4. serves to protect the lower airways
- 5. air passages inside the lungs that branch off like tree limbs
- 7. it allows for the movement of air from the nose and mouth
Down
- 1. where the lungs and the blood exchange oxygen and carbon dioxide
- 2. two external openings of the nasal cavity in vertebrates that admit air to the lungs
- 3. the air passage from the throat to the lungs
- 6. a pair of spongy, air-filled organs