The human lung consists of a spongy and elastic network of tissue and airways that are part of the respiratory system. Inside the lungs, there is a series of tubes, starting with the trachea, that branch out into increasingly smaller airways all the way down to the alveoli, the microscopic pockets where oxygen exchange between the lungs and the bloodstream takes place. There are a number of human lung diseases that can interfere with this respiratory functioning.
Inflammatory Diseases
Asthma is the most common inflammatory disease of the lungs. It is a chronic condition triggered by colds, allergies, changes in the weather and, in some people, exercise. Asthma occurs when inflammation causes narrowing of the airways, decreasing the lung's capacity to provide oxygen to the tissues. Patients with asthma exhibit dry cough, rapid breathing with retractions (pulling in of chest muscles), and wheezing caused by the movement of air through the narrowed airways. Treatment for asthma includes the use of bronchodilators for dilating the airways and steroids for reducing inflammation. Asthma can also be controlled by avoiding allergens and through the use of allergy medicines that reduce the reaction to allergens.
Pneumonias
The lungs are susceptible to infection by bacteria, viruses and fungi. Fever, difficulty breathing, chest pain and production of phlegm with cough characterize a bacterial pneumonia infection. These symptoms usually present acutely, within a few days of initial symptoms of upper respiratory infection, or cold. Atypical pneumonia, or walking pneumonia, usually presents more slowly, over days or weeks. Tuberculosis is another bacterial infection that can cause chronic pneumonia. Treatment for bacterial pneumonia includes appropriate antibiotics, oxygen supplementation if needed, and fluids.
Viral pneumonia presents with the same symptoms, only in milder form. Treatment for viral pneumonia is usually supportive care, with treatment of fever and fluids to prevent dehydration. The treatment of fungal pneumonia is more complicated, as these infections usually affect patients with deficient immune systems.
Cancer
Lung cancer occurs when cells start growing in an uncontrolled fashion. Lung cancer presents with cough that can be blood-tinged, or with frank blood, weight loss, chest pain, shortness of breath and fatigue. Lung cancer can start in the lung (primary lung cancer) or spread from other organs (secondary lung cancer). Cigarette smoke is a known risk factor for lung cancer. Treatment for lung cancer depends on the type of cancer and the stage at diagnosis.
