How Does Smoking Affect Your Respiratory System?

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How Your Respiratory System Works

To understand how smoking damages your respiratory system, you must understand how the system works. When you breathe in through the nose or mouth, you are taking in oxygen-rich air, which will eventually supply your body with the oxygen it needs to function.

Before the oxygen gets to your heart to be pumped throughout your body, it has to pass through your airways. It passes down your throat, through your larynx and trachea. The trachea divides into two smaller tubes, called the bronchi, which then divide into even smaller bronchial tubes. Your bronchial tubes lead directly into your lungs, where they divide into thousands of smaller-yet-again bronchioles.

At the end of each bronchiole is a delicate air sac called an alveolus, which is covered in capillaries–tiny blood vessels connected to arteries and veins. Capillaries on the alveoli allow the transfer of oxygen into the bloodstream and the waste product, carbon dioxide, out of the bloodstream and into the lungs. The same airways that brought in the oxygen carry out the carbon dioxide.

Tiny mucus-coated hairs called cilia line all your airways, except in parts of your nose and your mouth. The cilia trap particles and germs that may come into your body in the air you breathe. The cilia sweep the particles back up into your nose or mouth to be swallowed, coughed or sneezed from your body, according to the National Heart, Lung and Blood Institute.

The Effects of Smoking on Your Lungs

What does smoking do to the respiratory system when the smoker inhales at least 4,000 chemical substances with every drag of a cigarette? According to the National Cancer Institute, at least 250 of those chemicals are known to be harmful and more than 50 of those are known to cause cancer. Toxic chemicals in tobacco smoke include hydrogen cyanide, carbon monoxide, formaldehyde and ammonia.

To damage the respiratory system, hydrogen cyanide and the other toxins in the smoke first slow the sweeping of the cilia in the airways, and then paralyze them. As the cilia become shorter and eventually disappear, the toxic chemicals and mucus begin to build up in the lungs and must now be coughed up to be eliminated–the “smoker’s cough.” The smoker’s cough irritates the bronchi, leading to chronic bronchitis.

As the coughing and mucus production increase, the bronchioles thicken, and when they lose their elasticity, they cannot absorb the pressure from the alveoli, which subsequently rupture. Now, the smoker has emphysema, a type of chronic obstructive pulmonary disease (COPD). Smoking causes 90 percent of all COPD cases, according to the American Council on Science and Health. Because the alveoli can no longer facilitate the transfer of oxygen into the bloodstream, breathing is impaired, with increased cough, wheezing, and fatigue. At the same time cellular changes are taking place that often lead to lung cancer.

The Effects of Quitting Smoking

To reverse what smoking does to the respiratory system, you will have to quit the cigarette habit. In addition to the long-term benefits of reduced cancer risk and increased longevity, quitting smoking will have nearly immediate effects on the respiratory system.

After just a few hours, the amount of carbon monoxide in the bloodstream starts to decline, improving the ability of the blood to carry oxygen. The cilia start to regenerate and repair themselves. This process may increase coughing temporarily, notes Dr. Richard Hurt of the Mayo Clinic, but once the cilia have recovered (within a few weeks), mucus production decreases, as do cough and wheezing. Smokers who quit will not have to wait long to see significant improvement in lung and respiratory function.


National Heart, Lung and Blood Institute: The Respiratory System

National Cancer Institute: Quitting Smoking: Why to Quit and How to Get Help

American Council on Science and Health: The Scoop on Smoking

McGraw-Hill Higher Education: Seely et al/Anatomy and Physiology: The Effects of Cigarette Smoking on the Respiratory System

Mayo Clinic: Why Am I Still Coughing After I Quit Smoking