Across
- 5. refers to lungs
- 7. small air sacs
- 10. bottom chambers of heart
- 11. largest artery of heart
- 15. protects the lungs
- 16. breathing muscle
- 20. bronch______
- 21. air-filled organs
- 22. arteries carry blood ______ from heart
- 23. prevents blood flowing backwards
- 24. open space inside vessels
- 25. cells that carry oxygen
Down
- 1. gas needed for survival
- 2. carbon _________
- 3. helps to stop bleeding
- 4. cells that fight infection
- 6. carries blood to the heart
- 8. entrance chamber of heart
- 9. flows through vessels
- 12. aka windpipe
- 13. high to low concentration
- 14. smallest blood vessels
- 17. air pipes that split
- 18. liquid part of blood
- 19. outside of vessel