Bronchitis (pronounced: brong-kye-tis) is an inflammation of the lining of the bronchial tubes, the airways that connect the trachea (windpipe) to the lungs. This delicate, mucus-producing lining covers and protects the respiratory system, the organs and tissues involved in breathing.
When a person has bronchitis, it may be harder for air to pass in and out of the lungs, the tissues become irritated, and more mucus is produced. The most common symptom of bronchitis is a cough.
When you breathe in (inhale), small, bristly hairs near the openings of your nostrils filter out dust, pollen, and other airborne particles. Bits that slip through become attached to the mucus membrane, which has tiny, hair-like structures called cilia on its surface. But sometimes germs get through the cilia and other defense systems in the respiratory tract and can cause illness.
Bronchitis can be acute or chronic. An acute medical condition comes on quickly and can cause severe symptoms, but it lasts only a short time (no longer than a few weeks). Acute bronchitis is most often caused by one of a number of viruses that can infect the respiratory tract and attack the bronchial tubes. Infection by certain bacteria can also cause acute bronchitis. Most people have acute bronchitis at some point in their lives.
Chronic bronchitis, on the other hand, can be mild to severe and is longer lasting — from several months to years. With chronic bronchitis, the bronchial tubes continue to be inflamed (red and swollen), irritated, and produce excessive mucus over time. The most common cause of chronic bronchitis is smoking.
People who have chronic bronchitis are more susceptible to bacterial infections of the airway and lungs, like pneumonia. (In some people with chronic bronchitis, the airway becomes permanently infected with bacteria.) Pneumonia is more common among smokers and people who are exposed to secondhand smoke.
According to kidshealth