Across
- 2. The walls of the air sacks are only one ______ thick
- 6. Commonly known as your windpipe
- 7. The smaller branches of the tree
- 8. The two big tree branches
- 10. The gas that we inhale
- 11. The movement of gas molecules from an area of high concentration to an area of low concentration
Down
- 1. The small air sacks where gaseous exchange takes place
- 3. The air sacks are surrounded by _______ which provides a good blood supply
- 4. The main organ responsible for breathing
- 5. The gas that we exhale
- 9. The surface of the air sacks are ______ to allow gaseous exchange