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Respiratory and lung diseases

Respiratory or lung diseases include asthma, pneumonia, tuberculosis, lung cancer, and many others. Respiratory diseases are among the most prevalent and the most rapidly expanding in prevalence worldwide. Respiratory illnesses are health problems of the lungs or airways that sometimes make it difficult to breathe. They can either last a short amount of time, like with a cold, or they can last for years. Respiratory illnesses can be caused by a variety of indoor pollutants.

The respiratory system is the biological system of any organism that engages in gas exchange. Even trees have respiratory systems, taking in carbon dioxide and emitting oxygen during the day, consuming oxygen and producing carbon dioxide at night. The primary function of the respiratory system is to supply the blood with oxygen

in order for the blood to deliver oxygen to all parts of the body. The respiratory system does this through breathing. When we breathe, we inhale oxygen and exhale carbon dioxide. This exchange of gases is the respiratory system's means of getting oxygen to the blood. Air enters the body through the nose and mouth and travels down the trachea, through the bronchial tubes, and finally into the lungs. Once in the lungs, the air is drawn into an enormous number of thin-walled sacs richly supplied with capillaries. The exchange of oxygen and carbon dioxide in the blood takes place in these tiny sacs.

Lung diseases are health conditions that occur within the lungs. The lung is an organ belonging to the respiratory system and interfacing to the circulatory system of air-breathing vertebrates. Its function is to exchange oxygen from air with carbon dioxide from blood. The process in which this happens is called "external respiration" or breathing. There are also nonrespiratory functions of the lungs. The human lungs are paired organs, located on either side of the heart and occupying a large portion of the chest cavity from the collarbone to the diaphragm. Air enters the body through a series of passages, beginning with the nose or mouth. It travels to the chest cavity through the trachea, which divides into two bronchi, each of which enters a lung. The bronchi divide and subdivide into a network of countless tubules. The smallest tubules, or bronchioles, enter cup-shaped air sacs known as alveoli, which number about 700 million in both lungs. Each alveolus is surrounded by a net of capillaries. As blood flows through these vessels, carbon dioxide passes into the alveoli, and oxygen diffuses into the bloodstream. The capillaries are part of a vast network of pulmonary blood vessels that connect the lungs directly to the heart via the large pulmonary arteries and veins. The alveoli are clustered in groups, or lobules, and the lobules are clustered into lobes.

Lung disease is any disease or disorder where lung function is impaired. There are three major physiologic categories of lung diseases. Obstructive lung disease is a decrease in the exhaled air flow caused by a narrowing or blockage of the airways, such as with asthma, emphysema, and chronic bronchitis. Restrictive lung disease is a decrease in the total volume of air that the lungs are able to hold. Often, this is due to a decrease in the elasticity of the lungs themselves or caused by a problem related to the expansion of the chest wall during inhalation. Another category of lung disease is a defect in the ability of the lung's air sac tissue to move oxygen into a person's blood. Defective lung diseases decrease the lung's ability to move oxygen from its air sac tissues to the blood. Most lung diseases actually involve a combination of these categories, such as emphysema, which involves both airflow obstruction and oxygenation problems.


Common respiratory and lung diseases

Asthma - Asthma is a chronic inflammatory respiratory disease characterized by periodic attacks of wheezing, shortness of breath, and a tight feeling in the chest. Asthma is an immunological disease which causes difficulty in breathing. It is a form of type I hypersensitivity in which the bronchioles in the lungs are narrowed by inflammation and spasm of the lining of the airway wall. A person with asthma may experience wheezing, shortness of breath and poor exercise tolerance. Inflmmation occurs when irritated tissues swell and produce extra mucus, creating a condition known as bronchoconstriction.
COPD (Chronic obstructive pulmonary disease) - Chronic obstructive pulmonary disease (COPD) is persistent obstruction of the airways occurring with emphysema, chronic bronchitis, or both disorders. In COPD, airflow through the airways (bronchial tubes) within the lungs is partially blocked, resulting in difficulty breathing. Chronic obstructive pulmonary disease (COPD) encompasses two groups of lung disease, chronic bronchitis and emphysema. The leading risk factor for COPD is smoking, which can lead to the two most common forms of this disease, emphysema and chronic bronchitis.
Emphysema - Emphysema is a lung disease that reduces the ability of the lungs to expel air, a process which depends upon the natural rubber-band-like quality or elastic properties of the lungs. Emphysema is a type of chronic obstructive airway disease, or COPD. People with COPD have limitations in the flow of air through their airways. Emphysema involves the gradual destruction of alveoli in the lungs. The alveoli are air spaces where oxygen is exchanged with carbon dioxide in the blood. Emphysema is lung disease that occurs when the tiny air sacs in the lungs are damaged, usually as a result of long-term smoking.
Asbestosis - Asbestosis is a chronic progressive disease that requires high exposures to asbestos over prolonged periods of time and is characterised pathologically by interstitial fibrosis and asbestos bodies. Asbestosis is a consequence of prolonged exposure to large quantities of asbestos, a material once widely used in construction, insulation, and manufacturing. When asbestos is inhaled, fibers penetrate the breathing passages and irritate, fill, inflame, and scar lung tissue. In advanced asbestosis,, the lungs shrink, stiffen, and become honeycombed (riddled with tiny holes).
Lung cancer - Lung cancer is the cancer that originates in the tissues of the lungs. Lung cancer occurs when cells in the lung start to grow rapidly in an uncontrolled manner. Lung cancer can start anywhere in the lungs and affect any part of the respiratory system. It is the leading cause of cancer deaths in both men and women. Most lung cancers start in the lining of the bronchi. That is why another term for lung cancer is bronchogenic cancer. Lung cancer can also form in glands below the lining of the bronchi, frequently in the periphery of the lungs. Lung cancers are thought to develop over a period of many years. First, there may be areas of precancerous changes in the lung.
Mesothelioma - Mesothelioma cancer is a rare form of cancer (malignancy) that most frequently arises from the cells lining the sacs of the chest (the pleura) or the abdomen (the peritoneum). Mesothelioma (cancer of the mesothelium) is a disease in which cells of the mesothelium become abnormal and divide without control or order. They can invade and damage nearby tissues and organs. Cancer cells can also metastasize (spread) from their original site to other parts of the body. Most cases of mesothelioma begin in the pleura or peritoneum. Most cases of malignant mesothelioma cancer are caused by exposure to asbestos, a naturally occurring mineral that was used in a variety of industries.
Cystic fibrosis - Cystic fibrosis is a hereditary disease of the exocrine glands, usually developing during early childhood and affecting mainly the pancreas, respiratory system, and sweat glands. It is characterized by the production of abnormally viscous mucus by the affected glands, usually resulting in chronic respiratory infections and impaired pancreatic function. Cystic fibrosis is also called mucoviscidosis. Cystic fibrosis affects the pancreas, which normally produces enzymes needed to break down food during digestion, and also affects the glands that secrete sweat and mucus.
Severe acute respiratory syndrome (SARS) - Severe acute respiratory syndrome (SARS) - a contagious and sometimes fatal respiratory illness - first appeared in China in November 2002. SARS is a severe form of pneumonia, where infected individuals develop a fever, followed by respiratory symptoms such as cough, shortness of breath or difficulty breathing. In some cases, the respiratory symptoms become increasingly severe, and people require oxygen support and mechanical ventilation. It is not to be confused with the common cold.
Influenza - Influenza, usually known as the flu, is a respiratory infection caused by one of the influenza viruses that typically is spread by air or by direct contact. Most cases occur during epidemics, which peak during the winter months nearly every year. A particularly widespread and severe epidemic is called a pandemic. Influenza is spread primarily by aerosols, but occasionally through a fomite. The primary infection involves the ciliated epithelial cells of the upper respiratory tract. These cells begin necrosis that results in the usual acute respiratory infection symptoms including fever, chills, muscular aching, and headache.
Pneumonia - Pneumonia is an infection of the lungs. It involves the tiny air sacs, called alveoli, which are located at the tips of the body’s smallest breathing tubes, called the bronchi. The alveoli are responsible for passing oxygen into the blood. Pneumonia is an inflammation of the lung caused by infection with bacteria, viruses, or other organisms. Pneumonia is usually triggered when a person's defense system is weakened, most often by a simple viral upper respiratory tract infection or a case of influenza (the flu). Such infections or other triggers do not cause pneumonia directly but they alter the protective blanket of mucous in the lungs, thus encouraging bacterial growth.

Topics in respiratory and lung diseases

Lung diseases
Occupational lung diseases
Respiratory infections
Respiration disorders
Broncheal diseases
Pleural diseases
Lung transplant

Featured articles on respiratory and lung diseases

COPD (Chronic obstructive pulmonary disease)
Lung cancer
Pulmonary hypertension
Cystic fibrosis
Severe acute respiratory syndrome (SARS)

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