Across
- 2. ______ protect from the backflow of blood
- 4. The gas reactant in respiration
- 7. Taking air in
- 8. The balloon-like muscle under your lungs
- 9. The human body contains ____ litres of blood
- 11. The ___________ system is made up of the heart, blood vessels and blood
- 13. Commonly referred to as the windpipe
- 16. Cells created by bone marrow
- 19. Where cellular respiration takes place in the cell
- 21. Narrower arteries that branch off from the arteries & carry oxygenated blood to the capillaries
- 22. Tubes from trachea to lungs
- 24. Blood cells that help fight disease
- 27. Veins carry ____________ blood
- 29. The largest artery in the human body
Down
- 1. Air comes into the body via the _____ cavity
- 2. The largest vein in the human body
- 3. The primary organs of of the respiratory system
- 5. The flap that prevents food from going down the trachea
- 6. Two thin layers of tissue that protect and cushion the lungs
- 10. Breathing air out
- 12. The gas product in respiration
- 14. Type of blood vessels that carry oxygenated blood away from the heart
- 15. Smallest and thinnest of the blood vessels
- 17. The number of chambers in the heart
- 18. Heart valve that separates the right atrium from the right ventricle
- 20. Arteries carry __________ blood
- 23. The throat
- 25. The voice box
- 26. Large blood vessels that return deoxygenated blood from the body to the heart
- 28. Where gas exchange occurs