262 Unit 4 Understanding and Avoiding Hazardous Substances Copyright Goodheart-Willcox Co., Inc. Chronic bronchitis is an ongoing condition in which the bronchial tubes become swollen and irritated. Smoking causes the mucous mem- brane in the lungs’ bronchial passages to become inflamed, which narrows fl the pathway to the lungs. This makes it increasingly diffi for the lungs ficult to take in enough oxygen, which is why people with bronchitis often expe- rience coughing spells and have diffi catching their breath. Smoking ficulty and inhaling secondhand smoke are primary causes of chronic bronchitis, but regularly inhaling air pollution and smoke from tobacco products con- tributes to the condition as well. y Emp physema is a disease that causes the airways in the lungs to be- come permanently enlarged. Emphysema destroys the sacs of air that make up lung tissue (alveoli), which is where oxygen and carbon dioxide are traded during the breathing process. The destruction of the alveoli makes it more diffi to breathe. As a result, the person has to breathe ficult faster to get enough oxygen into the lungs and into the bloodstream. This extra work places a burden on the heart, leading to more health problems (Figure 9.4). Asthma and Other Illnesses. Asthma A is a chronic disease caused by blockages of the airfl to and from the lungs. When a person with asthma flow inhales tobacco smoke—either by smoking a cigarette or by being around people who are smoking—the lining of the airways becomes irritated. This irritation can then cause an asthma attack. Moreover, because tobacco smoke damages the cilia, they are unable to eliminate unwanted particles in the lungs. This means these particles stay in the airways and continue to trigger asthma attacks. Similarly, smoking interferes with a person’s ability to participate in even casual forms of physical activity. For example, after beginning to smoke, someone who once ran one lap around the track without becoming out of breath may be breathless after running half as far. This is because smoking leads to reduced lung capacity, and the hearts of smokers are al- ready overworked before they begin physical activity. Smoking also leads to a weakened immune system. Your immune system consists of the or- gans, tissues, and cells in the body that help defend itself from disease-causing agents such as bacteria, parasites, and viruses. Smokers are at greater risk of becoming ill from germs that cause colds and the flu. fl Tobacco use can lead to a number of other health problems. Smokers have a higher risk factor than nonsmokers for developing osteo- porosis, ulcers, fertility problems, and gum disease. Tobacco use can also interfere with eating by changing the shape of taste buds. When food does not taste as good, some long- term smokers lose their appetite and interest in eating. chronic bronchitis a condition in which the bronchial tubes swell and become irritated Below, on the left, is a healthy, normal lung. On the right is a smoker’s lung, which has been damaged in many ways. For example, constant irritation from the tar in smoke keeps a smoker’s lungs infl amed, resulting in a buildup of scar tissue that reduces the lung’s elasticity. Figure 9.4 emphysema a disease that permanently enlarges lung airways and destroys lung tissue, making it diffi for a ficult person to breathe asthma a chronic disease characterized by episodes of blocked airflow to the fl lungs