1. Small airways that branch off from the bronchi.

2. Act of inhaling and exhaling air for resupply of oxygen.

3. Breastbone to which the ribs are attached.

4. Muscle that plays a major role in breathing.

5. Process of gas exchange across membranes.

6. Infection that inflames air sacs in the lungs.

7. Air-filled cavities in the skull connected to the nasal passages.

8. Related to the lungs.

9. Process of taking air into the lungs.

10. Substance capable of filling any container it occupies.

11. Tiny hair-like structures that help in moving mucus.

12. Respiratory condition characterized by narrowed airways.

13. Process of expelling air from the lungs.

14. Air sacs in the lungs where gas exchange occurs.

15. Act of inhaling and exhaling smoke from tobacco or other substances.

16. Voice box located in the upper part of the trachea.

17. Thick mucus in the respiratory passages.