7. the is a strong wall of muscle that contracts to create a suction in the chest to draw in air and expand the lungs. when the muscle relaxes, the chest cavity decreases and air is pushed out.

8. janet smoked cigarettes since she was sixteen. now at age 45, she suffers from shortness of breath, coughing, fatigue, sleep and heart problems, weight loss, and depression. her condition is caused by a chronic lung that affects the alveoli. janet suffers from:
a) emphysema
b) lung cancer
c) chronic bronchitis
d) cilia degeneration

9. both marijuana and tobacco smoke contain which are substances that cause cancer:
a) delta-9-tetrahydrocannabinol (thc)
b) thiamine and dextrose
c) enzymes
d) carcinogens

10. which of the following statements is not true
a) smoking at an early age increases the risk of lung cancer. for most smoking-related cancer's, the risk rises as the individual continues to smoke.
b) teenage smokers suffer from shortness of breath almost three times as often as teens who don't smoke and produce phlegm more than twice as often as teens who don't smoke.
c) teenage smokers are more likely to have seen a doctor or other health professionals for an emotional or psychological complaint.
d) people who quit smoking cannot reverse any of the damage that has been done to their lungs over an extended period of time