Tobacco and the Respiratory System

The upper part of the respiratory system is generally able to filter out dust and foreign particles that could damage the lungs. Millions of people engage in an activity—smoking tobacco—that damages and eventually destroys this protective system.

Substances in Tobacco Tobacco smoke contains many substances that affect the body. Three of the most dangerous substances are nicotine, carbon monoxide, and tar. Nicotine is a stimulant drug that increases the heart rate and blood pressure. Carbon monoxide is a poisonous gas that blocks the transport of oxygen by hemoglobin in the blood. It decreases the blood's ability to supply oxygen to its tissues, depriving the heart and other organs of the oxygen they need to function. Tar contains a number of compounds that have been shown to cause cancer.

Smoking tobacco brings nicotine and carbon monoxide into the upper respiratory system. These compounds paralyze the cilia. With the cilia out of action, the inhaled particles stick to the walls of the respiratory tract or enter the lungs.

Without cilia to sweep it along, smoke-laden mucus becomes trapped along the airways. This explains why smokers often cough. Irritation from the accumulated mucus triggers a cough that helps to clear the airways. Smoking also causes the lining of the respiratory tract to swell, which reduces the air flow to the alveoli.

Diseases Caused by Smoking Only 30 percent of male smokers live to age 80, but 55 percent of male nonsmokers live to that age. Clearly, smoking reduces life expectancy.   Smoking can cause such respiratory diseases as chronic bronchitis, emphysema, and lung cancer. In chronic bronchitis, the bronchi become swollen and clogged with mucus. Even smoking a moderate number of cigarettes on a regular basis can produce chronic bronchitis. Affected people often find simple activities, such as climbing stairs, difficult.

Long-term smoking can also cause a respiratory disease called emphysema (em-fuh-SEE-muh). Emphysema is the loss of elasticity in the tissues of the lungs. This condition makes breathing very difficult. People who have emphysema cannot get enough oxygen to the body tissues or rid the body of excess carbon dioxide.

Smoking is an important, but preventable, cause of lung cancer. The figure below shows the effects of smoking on the lungs. Lung cancer is particularly deadly because its cells can spread to other locations. By the time lung cancer is detected, it usually has spread to dozens of other places. About 160,000 people in the United States are diagnosed with lung cancer each year. Few will survive for five years after the diagnosis.

Smoking and the Lungs   Smoking can cause respiratory diseases such as chronic bronchitis, emphysema, and lung cancer. The lung on the left is from a smoker. The lung on the right is from a nonsmoker.

Smoking is also a major cause of heart disease. Smoking constricts, or narrows, the blood vessels. This causes blood pressure to rise and makes the heart work harder. There is a drastic change in body temperature and in circulation immediately after smoking a cigarette. Smoking doubles the risk of death from heart disease for men between 45 and 65. Moreover, for men and women of all ages, the risk of death from heart disease is greater among smokers than among nonsmokers.

Smoking and the Nonsmoker In recent years, evidence has shown that tobacco smoke is damaging to anyone who inhales it, not just the smoker. For this reason, many states have restricted smoking in restaurants and other public places.

Passive smoking, or inhaling the smoke of others, is particularly damaging to young children because their lungs are still developing. Studies now indicate that the children of smokers are twice as likely as children of nonsmokers to develop respiratory problems, such as asthma.

Dealing With Tobacco Whatever the age of a smoker, and no matter how long that person has smoked, his or her health can be improved by quitting. Nicotine is a powerful drug with strong addictive qualities that make it very difficult to quit smoking. Thus, considering the cost, the medical dangers, and the powerful addiction, the best solution is not to begin smoking.