The lungs are made of delicate elastic tissue that inflates and deflates as air is inhaled and exhaled, respectively. Blood vessels that line tiny sacs in the lungs called alveoli absorb oxygen that then travels through the blood stream to the body's tissues. Lung diseases disrupt the exchange of oxygen and carbon dioxide. There are several distinct causes of lung disease.
Irritants
Any small particles present in the air can be inhaled during normal breathing. Sometimes these particles act as irritants, meaning they trigger inflammation in the lungs as well as asthma attacks. Inhalation of irritants long-term can cause permanent damage to the lungs. A common irritant to the lung tissue is cigarette smoke, whether it is inhaled directly or second hand. The American Lung Association reports that cigarette smoking causes emphysema, lung cancer, chronic bronchitis, heart disease and stroke. The association adds that 430,000 people in the U.S. die each year from the effects of breathing in cigarettes smoke.
Genes
Inheriting certain forms of genes can predispose people to the development of certain types of lung diseases. For example, cystic fibrosis is a lung disease that is caused by a defective gene, according to the Cystic Fibrosis Foundation. Instead of coding for a normal protein, the protein produced by the defective gene is itself defective. The defective protein results in the production of very sticky and thick mucus that clogs the lungs. The signs and symptoms of cystic fibrosis include shortness of breath, coughing and persistent lung infections.
Allergies
In addition to irritants, certain people may also have asthma attacks in response to breathing in substances to which they are allergic. When an allergic person prone to having asthma attack breathes in an allergen, the tissue of the airway responds quickly by becoming swollen and inflamed, and the muscles surrounding the airways constrict. The Asthma and Allergy Foundation of America reports that more than 50 percent of the 20 million people affected by asthma attacks have allergic asthma. The foundation also notes that common allergens that trigger asthma attacks include dust mite allergen, pollen, mold, and pet dander.
Infection
When a microbe infects the lungs, the resulting infection causes inflammation, swelling and mucus production. A variety of different types of microbes infect the lung, including bacteria, viruses and fungi, according to MedlinePlus, a website of the National Institutes of Health. The inflammation caused by infection with the microbe is clinically called pneumonia. The typical signs and symptoms of pneumonia include coughing, difficulty breathing and a fever.
