Lung Diseases Affecting the Air Sacs (Alveoli)
The airways eventually branch into tiny tubes (bronchioles) that dead-end into clusters of air sacs called alveoli. These air sacs make up most of the lung tissue. Lung diseases affecting the alveoli include:
- Pneumonia: An infection of the alveoli, usually by bacteria.
- Tuberculosis: A slowly progressive pneumonia caused by the bacteriaMycobacterium tuberculosis.
- Emphysema results from damage to the fragile connections between alveoli. Smoking is the usual cause. (Emphysema also limits airflow, affecting the airways as well.)
- Pulmonary edema: Fluid leaks out of the small blood vessels of the lung into the air sacs and the surrounding area. One form is caused by heart failure and back pressure in the lungs' blood vessels; in another form, direct injury to the lung causes the leak of fluid.
- Lung cancer has many forms, and may develop in any part of the lungs. Most often this is in the main part of the lung, in or near the air sacs. The type, location, and spread of lung cancer determines the treatment options.
- Acute respiratory distress syndrome (ARDS): Severe, sudden injury to the lungs caused by a serious illness. Life support with mechanical ventilation is usually needed to survive until the lungs recover.
- Pneumoconiosis: A category of conditions caused by the inhalation of a substance that injures the lungs. Examples include black lung disease from inhaled coal dust and asbestosis from inhaled asbestos dust.