The Respiratory System - Ailments: what can go wrong with the respiratory system

Since the respiratory system is open to airborne microorganisms and out-side pollution, many ailments or maladies can afflict it. Some respiratory disorders are relatively mild and, unfortunately, very familiar. Excess mucus (runny nose), coughing, sneezing, nasal congestion, headache, sore throat, muscle aches, and tiredness are all symptoms of the common cold. A viral infection of the upper respiratory system, the common cold can be caused by one of over 200 different viruses. An average individual usually suffers from between 50 and 100 colds during his or her life. Almost all colds clear up in less than two weeks without complications.

When a cold lingers beyond that time period, the cause may be an inflammation of the sinuses, a condition called sinusitis. Caused by a bacterial infection, sinusitis is often mistaken for a common cold because the symptoms are somewhat similar. With sinusitis, congestion may be the same or even worse. While drainage from the nose during a common cold is often clear, drainage due to sinusitis is often thick and yellowish-green in color. Sinus pain and pressure is frequent. A sore throat and bad breath, resulting from drainage dripping down the back of the throat, may also occur. Antibiotic medications are often necessary to treat sinusitis.

Allergies, abnormal immune reactions to otherwise harmless substances, are among the most common of medical disorders. Symptoms depend on the specific type of allergic reaction. In the most common type of reaction, symptoms can mimic those of a nasal cavity infection: pressure, pain, a runny nose, congestion, and a scratchy or irritated throat.

The following are some of the more serious—and often fatal—disorders and diseases that can impair the functioning of the respiratory system or its parts.


Asthma is a chronic (long-term) inflammatory disease of the airways. Although the cause for the condition is unknown, it is known that allergies can trigger an asthma attack. Continuing inflammation makes the airways hypersensitive to stimuli such as cold air, exercise, dust mites, air pollutants, and even stress and anxiety. All can then give rise to an asthma attack.

Asthma usually begins in childhood or adolescence, but it also may first appear during adult years. An estimated 15 million people in the United States suffer from asthma. More than 5,600 people die of severe asthma attacks each year.

Asthma (AZ-ma): Respiratory disease often caused by an allergy that is marked by tightness in the chest and difficulty in breathing.

Bronchitis (bron-KIE-tis): Inflammation of the mucous membrane of the bronchial tubes.

Cystic fibrosis (SIS-tik fie-BRO-sis): Genetic disease in which, among other things, the mucous membranes of the respiratory tract produce a thick, sticky mucus that clogs airways.

Emphysema (em-feh-ZEE-mah): Respiratory disease marked by breathlessness that is brought on by the enlargement of the alveoli in the lungs.

Pneumonia (noo-MOE-nya): Disease of the lungs marked by inflammation and caused by bacteria or viruses.

Tuberculosis (too-burr-cue-LOW-sis): Infectious, inflammatory disease of the lungs caused by a bacteria that results in tissue damage.

In an asthma attack, the muscle tissue in the walls of the bronchi and bronchioles go into spasm. As a result, the cells lining the airways swell and secrete mucus into the air spaces. Both these actions cause the bronchi and bronchioles to become narrowed. This, in turn, produces a tightness in the chest, wheezing, and breathlessness, sometimes to the point where an individual gasps for air. Asthma attacks come and go in irregular patterns, and they vary in degree of severity. Some may last only a few minutes; others may go on for much longer.

Treatment for asthma usually includes identifying the specific substance causing the allergic reaction and subsequently avoiding contact with it. Drugs are often given to relax the muscles of the bronchial tubes and allow increased air flow. They may be taken by mouth or inhaled through a nebulizer, a device that delivers a regulated flow of medication into the airways.


Bronchitis is an inflammation of the mucous membranes of the lower respiratory passages, especially the trachea and bronchi. Bronchitis can either be acute (short-term) or chronic (long-term).

A comparison of normal bronchioles and those of an asthma sufferer. (Illustration by Hans & Cassady.)
A comparison of normal bronchioles and those of an asthma sufferer. (Illustration by
Hans & Cassady

Acute bronchitis usually follows a viral infection such as a cold or the flu. Anyone can be afflicted with the disorder, but infants, young children, and the elderly are more susceptible because their body immunity (ability to fight disease) is generally weaker. Acute bronchitis usually begins with the symptoms of a cold: runny nose, sneezing, and a dry cough. However, the cough soon becomes deep and painful, and it will bring up greenish-yellow phlegm. High fever and wheezing are also common.

If no additional infection is present, acute bronchitis is treated in the same way as the common cold: drinking plenty of fluids, resting, not smoking, and taking acetaminophen for fever and pain. If an additional infection exists, the infection is treated with an antibiotic. When treated, acute bronchitis usually resolves in one to two weeks without complications.

Chronic bronchitis is a major cause of disability and death in the United States, affecting an estimated 14 million people. The disorder is caused by inhaling respiratory irritants, especially cigarette smoke. The American Lung Association estimates that 80 to 90 percent of all cases are caused by smoking. Other irritants include chemical fumes, air pollution, mold, and dust.

Chronic bronchitis develops slowly over time. When smoke or other irritants are inhaled, the cilia projecting from the mucous membrane lining the respiratory tract become paralyzed or snap off. Airways then become inflamed, narrowed, and clogged with mucus, making breathing difficult. A mild cough, sometimes called smokers' cough, is usually the first symptom. Wheezing and shortness of breath may accompany the cough. As the disease advances, breathing becomes even more difficult and activity decreases.

There is no cure for chronic bronchitis and treatment to help reduce symptoms is complex. As in asthma attacks, drugs may be given to relax the muscles of the bronchial tubes and allow increased air flow. The drugs may be taken by mouth or inhaled through a nebulizer, a device that delivers a regulated flow of medication into the airways. To further reduce the swelling of airway tissue, anti-inflammatory drugs may also be prescribed. As the disease progresses, an individual may be required to breathe supplemental oxygen.

The best way to prevent either type of bronchitis is to stop smoking or not even to begin.

Cystic fibrosis

Cystic fibrosis is an inherited or genetic disease, meaning it is caused by a defect in a person's genes. It affects the lungs, digestive system, sweat glands, and male fertility (ability to produce offspring or children). The disease affects about 30,000 children and young adults in the United States. Approximately 3,000 babes are born each year with cystic fibrosis.

Cystic fibrosis affects the body's ability to move salt and water in and out of cells. This defect causes the lungs and pancreas to secrete thick mucus, blocking passageways and preventing proper functioning. The disease derives its name from the fibrous scar tissue that develops as a result in the pancreas.

In the lungs, the thickened mucus increases irritation and inflammation of lung tissue. This inflammation swells the passageways, partially closing them down. At the same time, infection from bacteria or viruses becomes more likely since the mucus is a rich source of nutrients. Bronchitis and pneumonia frequently develop in individuals with cystic fibrosis.

The body's response to the infection is to increase mucus production. White blood cells fighting the infection thicken the mucus even further as they break down and release their cell contents. These white blood cells also provoke more inflammation. The process is a downward spiral as a person suffering from the disease experiences ever-increasing shortness of breath and tiredness. Untreated, cystic fibrosis leads to severe lung infection, which is the primary cause of death.

There is no cure for cystic fibrosis. Regular monitoring and early treatment are key to maintaining respiratory health. Good general health, especially good nutrition and exercise, can keep the body's immune response working properly. This, in turn, can help decrease the number of infections started by the bacteria always present in the lungs of infected individuals.

Clearing mucus from the lungs also helps to prevent infection, and devices and techniques have been developed to help in this regard. Several drugs are available to prevent the airways from becoming clogged with mucus. Lung transplants have become increasingly common for people with cystic fibrosis. About 50 percent of adults and 80 percent of children who receive lung transplants live longer than two years.


Emphysema is a respiratory disease marked by breathlessness that is brought on by the enlargement of the alveoli in the lungs. It is the most common cause of death from respiratory disease in the United States. Emphysema occurs mainly among people who are fifty years of age or older. Heavy cigarette smoking is the primary cause of the disease, although a few cases are caused by an inherited defect.

When a person inhales cigarette smoke, that person's body releases substances that are meant to defend the lungs against the smoke. These substances can also attack the cells of the lungs. Normally, the body prevents such action by releasing other substances. In smokers and those with the inherited defect, no such prevention occurs. Lung tissue is then damaged in such a way that it loses its elasticity. Bronchioles collapse, trapping air in the alveoli. Unable to contract efficiently and move air out, the alveoli overexpand and rupture. The alveoli blend together, forming large air pockets from which air cannot escape. This cuts down the surface area for gas exchange.

As the disease progresses, coughing and shortness of breath occur. Exhaling becomes difficult. Over several years, the extra work of exhaling can cause the chest to enlarge and become barrel-shaped.

Emphysema is a serious and long-term disease that cannot be reversed. The body cannot repair the damage to the lungs. Ultimately, the disease can lead to respiratory failure. If emphysema is detected early, medications may be given to help relax and open air passages, thus reducing some of the symptoms. Mild exercise may be ordered to help strengthen muscles involved in

A healthy lung (on the left) and a smoker's lung (on the right). (Photograph by A. Glauberman. Reproduced by permission of Photo Researchers, Inc.)
A healthy lung (on the left) and a smoker's lung (on the right). (Photograph by
A. Glauberman
. Reproduced by permission of
Photo Researchers, Inc.

breathing. An individual suffering from emphysema must stop smoking immediately or no treatments will be effective at all.

Lung cancer

Lung cancer develops when cells of the lung tissues become abnormal and grow uncontrollably, forming tumors. It is the leading cause of death from cancer among both men and women in the United States. Approximately 160,000 people die from the disease each year.

Tobacco smoking is the leading cause of lung cancer. Ninety percent of lung cancers can be prevented by giving up tobacco. Smoking marijuana cigarettes is considered yet another risk factor for lung cancer. These cigarettes have a higher tar content than tobacco cigarettes. In addition, they are inhaled very deeply. As a result, the smoke is held in the lungs for a longer time.

Other causes of lung cancer include exposure to asbestos, toxic chemicals, radioactive minerals, environmental pollution (such as auto exhaust fumes), and a family history of lung cancer.

Lung cancers tend to spread very quickly to other parts of the body. Early symptoms to watch for include a cough that does not go away, chest pain, shortness of breath, persistent hoarseness, swelling of the neck and face, significant weight loss, unexplained fever, bloody or brown-colored spit or phlegm, and recurrent lung infections.

The most common treatment options for lung cancer include surgery, chemotherapy, and radiation. During surgery, surgeons may remove a small part of the lung, one lobe of the lung, or the entire lung. The extent of the surgery depends on how much of the lung is affected. After the cancer has been removed, the physician may recommend chemotherapy (using a combination of drugs to kill any remaining cancer cells and shrink any tumors) or radiation therapy (using X rays or other high-energy rays to kill any remaining cancer cells and shrink any tumors) or a combination of both. Either or both of these methods may be used to shrink the tumor before surgery is attempted.

Almost 50 percent of lung cancer patients survive if the cancer is detected before it has had a chance to spread to other organs and it is treated appropriately. Only 15 percent of lung cancers, however, are found at this early stage. The best way to prevent lung cancer is not to smoke at all or to quit smoking if one has already started. Secondhand smoke from other people's cigarettes should also be avoided.


Pneumonia is an infection of lung tissues. It can be caused by nearly any organism known to cause human infections. This includes bacteria, viruses, fungi, and parasites. Pneumonia is the sixth most common disease leading to death in the United States. It is also the most common fatal infection acquired by people who are already hospitalized.

Pneumonia develops when the several types of immune substances in the respiratory tract are weakened to the point where invading organisms can take over. Once they do so, an infection develops in the normally sterile environment of the lungs. Symptoms include fever, cough, chest pain, shortness of breath, and increased respirations (number of breaths per minute). Many people cough up sputum (commonly known as spit) streaked with pus or blood.

Breathing is not the only process by which humans move air in and out of the lungs. Some processes or actions are reflexes initiated to clear air passages. Others are indications or extensions of emotional states. The following is a list of these common actions and how they are brought about:

Coughing: Reflex that removes irritants from the mucous membrane of the pharynx, larynx, or trachea. A deep inhalation is suddenly followed by an exhalation with the glottis temporarily closed. After pressure has built up, the glottis suddenly opens and an explosive exhalation is directed out of the mouth.

Crying: Action brought on by an emotional state. Inhalation followed by a number of short exhalations while the glottis is open and the vocal cords vibrate.

Hiccuping: Sudden inhalations when the diaphragm abruptly contracts. Sound produced when glottis closes suddenly to stop the inhalation. May be caused by an irritation of the diaphragm or the nerves that serve the diaphragm.

Laughing: Action brought on by an emotional state that produces basically the same air movements as crying.

Sneezing: Reflex that removes irritants from the mucous membrane of the nasal cavity. Action is the same as in coughing, except that oral cavity is closed off by the uvula (fleshy projection hanging from the soft palate) and the explosive exhalation is directed out of the nose.

Yawning: Reflex whose purpose or stimulus is not fully known. Tiredness, boredom, and seeing another person yawn all seem to trigger yawning. Very deep inhalation with jaws wide open brings tidal air to all alveoli.

The invading organism causes symptoms by provoking the body to launch an overly strong immune response in the lungs. That response, which should help fight the infection, instead damages lung tissue and makes it more susceptible to infection. Capillaries in the lungs become leaky and the fluid seeps into the alveoli. Mucus production in the lungs is increased. The alveoli further fill with fluid and debris from the large number of white blood cells being produced by the body to fight the infection. The amount of oxygen delivered to the rest of the body is then decreased.

Before the discovery of penicillin antibiotics, bacterial pneumonia was almost always fatal. Today, antibiotics are very effective against bacterial causes of pneumonia when given early in the course of the disease.


Tuberculosis (TB) is a potentially fatal infectious disease caused by a bacterium that can affect almost any part of the body. However, it is mainly an infection of the lungs. Although TB can be treated, cured, or even prevented if persons at risk take certain drugs, scientists have never come close to wiping it out. Popularly known throughout history as consumption, TB currently affects an estimated 8 to 10 million people worldwide each year. Roughly 3 million people die from the disease each year.

TB is usually contracted by inhaling air sneezed or coughed by someone who is suffering from the disease. Once inhaled, the bacterium reaches the alveoli. Actual tissue damage in the lungs is not caused directly by the bacterium, but by the reaction of a person's tissues to its presence. The infection may progress until large areas of the lung have been destroyed.

An infected person may at first feel vaguely ill or develop a cough blamed on smoking or a cold. A small amount of greenish or yellow sputum (spit) may be coughed up upon arising in the morning. In time, more sputum is produced that is streaked with blood. Chest pain, a low-grade fever, night sweats, loss of weight, difficulty breathing, and weakness are symptoms in advanced cases.

Individuals with TB can be treated at home with a combination of prescribed drugs. If the drugs are not effective, surgery to repair the damaged lung or remove part or all of it may be performed. If the disease is diagnosed early and prompt treatment is given, the recovery rate for TB sufferers is very good.

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