1. oxygen carbon dioxide The respiratory system is the system of the body that deals with breathing. When we breath, the body takes in the oxygen it needs and removes the carbon dioxide that it doesn’t need.

2. The bronchi divide into two smaller passages called the bronchioli. Air passes through the bronchioles into the alveoli, which are surrounded by capillaries. This is where gas exchange takes place: oxygen goes into your bloodstream and the carbon dioxide from the blood enters the alveoli.

3. The breathing process begins when you 1. inhale. The 2. diaphragm moves down and the rib cage 3. expands, creating more room in your chest. This causes air to rush into your body through the 4. nose or 5. mouth; then it moves past the 6. epiglottis and into the 7. trachea and 8. bronchi. Inside the lungs, the 9. bronchi divide into smaller passages called 10. bronchioles. Air passes through the 11.bronchioles into microscopic air sacs called 12. alveoli which are surrounded by 13. capillaries. Here the oxygen in the air moves into your 14. bloodstream, and carbon dioxide from the blood enters the 15. alveoli. The breathing process ends when you 16.exhale. Your 17.diaphragm pushes up, and your ribs move in and down, forcing the air out of your 18. lungs. The air, now containing carbon dioxide, moves back through the 19. bronchioles and bronchi, up the trachea, and out through the nose or 20. mouth.

4. ??????? What is the relationship between tobacco and these diseases?