Across
- 3. A colorless, poisonous chemical in the tobacco plant.
- 6. The process of inhaling and exhaling.
- 8. Two spongy saclike respiratory organs.
Down
- 1. The act or process of discharging waste.
- 2. A pair of organs in the excretory system.
- 4. The two branches of the trachea that extend into the lungs.
- 5. A muscular membrane of the body.
- 7. Cartilaginous tube descending from the larynx to the bronchi.