The lungs are organs of gas exchange in the body. They provide oxygen to the blood and remove carbon dioxide, a byproduct of metabolism, from blood. The regulation of carbon dioxide also modifies the acidity, or pH, of the blood. The lungs are composed of progressively smaller airways leading to alveoli, which are millions of tiny sacs that participate in gas exchange. They also have small blood vessels called capillaries running alongside the alveoli and connective tissue to support these functional structures. A variety of diseases can affect the lungs.
Congenital Abnormalities
Congenital means "at birth." There are numerous congenital disorders of the lungs. Congenital lung disorders frequently cause trouble breathing and pneumonias. One example of a congenital lung disorder is a CCAM, or congenital cystic adenomatoid malformation. CCAMs were reviewed in an article published in 2004 in the "European Journal of Cardio-Thoracic Surgery" by Ganesh Shanmugam, M.D., a cardiothoracic surgeon at IWK Health Center, a Canadian research and teaching center whose care extends from primary care up to specialized care of difficult-to-treat diseases. These diseases consist of part of a lung being replaced with a cyst, or nonfunctional cavity. The outcome is usually favorable. Another example is pulmonary sequestration. This occurs when a segment of normal lung tissue is not attached to the blood supply or the rest of the lungs, making it nonfunctional.
Inherited Genetic Diseases
Genetic problems can affect numerous organ systems, including the lungs. Cystic fibrosis is a genetic problem that causes a sticky, thick mucus to build up in the lungs and digestive tract. In the lungs, it can cause coughing, increased mucus, shortness of breath and recurrent bouts of pneumonia.
Vascular Disorders
The lungs have a rich blood supply to facilitate gas exchange. Disorders with blood vessels, called vasculitis, can lead to lung problems. Wegener's granulomatosis causes inflammation of the blood vessels in the lungs, kidneys and upper airway. This can restrict blood flow to the lungs and cause breathing problems and coughing up blood.
Obstructive Diseases
Obstructive lung diseases cause air flow problems in the lungs. Chronic obstructive lung disease, or COPD, and asthma are both obstructive lung diseases. COPD includes chronic bronchitis and emphysema. Chronic bronchitis includes narrowing of the airways and increased mucus production. Emphysema is the loss of functional lung tissue, causing empty spaces in the lungs. Both are commonly caused by smoking. Asthma also causes narrowing of the airways and excessive mucus production, but is caused by excessive airway responsiveness to environmental triggers such as animal dander, according to the 2008 edition of "Harrison's Principles of Internal Medicine" by Dr. Anthony Fauci, a director at the National Institutes of Health, and colleagues.
Restrictive Diseases
Restrictive lung diseases prevent the expansion of the lungs or chest wall. One example is idiopathic pulmonary fibrosis. In this disorder, normal elastic and pliable lung tissue is replaced with stiff inflexible scar tissue. The lungs do not expand well, making breathing difficult, especially with activity.
Cancers
Lung cancer is the overgrowth of cells in the lungs. One classification divides lung cancers into small cell and non-small cell types. Small cell typically has a worse outcome. It is not operable, but may be treated with chemotherapy or radiation. Non-small cell has a more favorable outcome and is more often treatable with surgery.
Infections
Infections in the lungs are called pneumonias. Lobar pneumonia affects an entire lobe or entire lung. Bronchopneumonia causes patches of infections around an airway. Pneumonias can be caused by bacteria, viruses or fungi.
References
- "European Journal of Cardio-Thoracic Surgery"; Congenital lung malformations---antenatal and postnatal evaluation and management; Shanmugam et al; November 2004
- "Harrison's Principles of Internal Medicine"; Anthony Fauci, M.D., et al.; 17th Ed.; 2008
- PathologyOutlines: Lung: Non-Tumor
