When you breathe in, air passes through your mouth or nose into your pharynx This divides into the gullet which takes food to the stomach, and the larynx which contains the vocal cords. The oxygen-rich air continues on down the trachea (windpipe), which is a cartilaginous tube of 1-2 cm diameter, situated in the front of the neck.
Behind the top of your breast bone, the trachea divides into a left and right main bronchus, one for each lung. In the lung, the bronchi divide into smaller and smaller tubes called bronchioles before ending up in an intricate network of billions of microscopic bubbles called alveoli. The alveoli are covered in a fine network of blood-containing capillaries, and it is here that oxygen is taken from the air into the blood. When you exhale, the air makes the long reverse journey from the alveoli to the outside carrying the waste carbon dioxide.
The dust, pollens and other fine particles of matter that enter the lungs are removed by a watery mucus that lines the air passages. This mucus is moved rapidly along and out of the lungs by the waving motion of fine microscopic hairs that cover the inner surface of all the bronchi and bronchioles.
Bronchitis is an infection of the major tubes (the bronchi) that carry air within the lungs. Pneumonia is an infection of the smaller bronchioles and alveoli. Bronchitis is a very common condition, and occurs in two very different forms, acute and chronic.
Acute bronchitis is most commonly caused by a viral infection, frequently by infection with bacteria, and rarely by a fungus. You can answer this question “Is Bronchitis Contagious?” Once the invading organism settles on the inside of the bronchi, it starts multiplying into vast numbers. This causes swelling and inflammation of the tissue, and the mucus in the tubes becomes thick and purulent with the infection. The cleaning mechanism of the lungs no longer works efficiently, phlegm plugs up the bronchi, and coughing is stimulated by the body in an attempt to clear the blockage.
The diagnosis is made by the doctor listening through a stethoscope to the pops, squeaks and whistles made by the air as it rushes in and out of the partly blocked bronchi. In the early stages, X-rays may be quite normal. Viral bronchitis cannot be cured, but it settles with time, rest, inhalations, bronchodilators (drugs to open up the bronchi) and physiotherapy. If a bacterial cause is suspected, antibiotics will also be prescribed.
Chronic bronchitis is due to repeated attacks of acute bronchitis, long-standing allergies, or constant irritation of the bronchi by noxious gases, particularly those found in tobacco smoke. Patients have a chronic cough, are short of breath, are unable to take much exertion, and may be blue around the lips. Their finger tips may become rounded and swollen in a process known as ‘clubbing’. X-rays can easily make the diagnosis as the thickened, scarred bronchi and poor air entry to the lungs show up quite markedly.
Chronic bronchitis is a semi-permanent condition for which there is no effective cure, but physiotherapy and medications to improve air flow, and antibiotics to treat any infection can be used to keep the condition under control for many years. The vast majority of victims are smokers. The disease may progress on to emphysema, and is sometimes associated with lung cancer.