The lungs are an important part of the human body and are responsible for providing oxygen to the bloodstream while removing carbon dioxide. Lung disease can be classified as any of a number of disorders that cause the lungs to no longer function normally. These illnesses and their severity can range all the way from those that are benign, causing no harm, to those that can be crippling or even lead to death.
There are three main categories of lung disease. The first of these is obstructive lung disease, which happens when airflow that is exhaled from the lungs is decreased because the airways have been either blocked or decreased in size. The main symptom is shortness of breath, and examples include asthma and chronic bronchitis. One the main causes of this type (and many more) is smoking, which can also be one of its main preventive measures when the smoker quits.
Restrictive lung disease is associated with a decrease in the capacity of the volume of air that the lungs are able to contain. The lungs are quite elastic, and these types of diseases can occur when this elasticity decreases. There can also be issues related to the expansion of the chest wall that cause these illnesses. In both of these cases, it becomes difficult for the lungs to deliver the amount of oxygen to the body that it needs. Common examples are interstitial lung disease and extrapulmonary restrictive lung disease.
The final category of lung disease is caused when there are defects in the tissues of the air sacs of the lungs, and this decreases the amount of oxygen that the lungs are able to deliver to the bloodstream. In most, it is a combination of these three categories that cause the lungs to function improperly, for example in emphysema. Other common types include chronic obstructive pulmonary disease (COPD), pulmonary fibrosis and sarcoidosis.