2. This system transports nutrients, hormones, and other materials to and from the cell of the body.

(a)  

3. The atrium that receives an oxygenated blood coming from the lungs.

(a)  

4. This flap of cartilage prevents food from reaching the lower respiratory tract.

(a)  

5. It is the main organ of the respiratory system.

(a)  

6. Part of the lower respiratory tract where gas exchange occurs.

(a)  

7. The blood vessel that sends deoxygenated blood to the lungs for oxygenation.

(a)  

8. This chamber of the heart pumps oxygenated blood to all parts of the body.

(a)  

9. This organ protects the respiratory system from accumulation of foreign materials.

(a)  

10. This organ of the respiratory system serves as the pathway for both air and food.

(a)  

11. This blood vessel conveys blood coming from all parts of the body going back to the heart of oxygenation.

(a)  

12. A type of respiration where gas exchange occurs between blood and blood cells.

(a)  

13. This valve prevents blood backflow from the left ventricle back to the left atrium.

(a)  

14. The type of gas that humans and most animals exhale.

(a)  

15. Once the deoxygenated blood is in the pulmonary artery, this valve prevents blood backflow back to the right ventricle.

(a)  

16. This is the largest artery that sends oxygenated blood to the different parts of the body.

(a)  

17. These are tiny branches of the bronchi that leads air into the alveoli.

(a)  

18. These arteries supply oxygenated blood to the heart.

(a)  

19. This organ is the main entrance of air and the exit point for carbon dioxide.

(a)  

20. In this blood vessel, exchange of gases and other materials take place and is in between arterioles and venules.

(a)