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Respiratory System Diseases

Introduces bronchitis, asthma, pneumonia, tuberculosis, lung cancer, and emphysema.

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What's this boy doing?

This inhaler can help ease the symptoms of asthma. The boy may have felt an asthma attack coming on. Tightness in his chest and difficulty breathing are common signs of an asthma attack. He is fortunate that asthma can usually be controlled with medicine.

Diseases of the Respiratory System

Respiratory diseases are diseases of the lungs, bronchial tubes, trachea, nose, and throat (Figure below). These diseases can range from a mild cold to a severe case of pneumonia. Respiratory diseases are common and may cause illness or death. Some respiratory diseases are caused by bacteria or viruses, while others are caused by environmental pollutants, such as tobacco smoke. Some diseases are genetic and, therefore, are inherited.

This boy is suffering from whooping cough (also known as pertussis), which gets its name from the loud whooping sound that is made when the person inhales during a coughing fit.


Bronchitis is an inflammation of the bronchi, the air passages that conduct air into the lungs. The bronchi become red and swollen with infection. Acute bronchitis is usually caused by viruses or bacteria, and may last several days or weeks. It is characterized by a cough that produces phlegm, or mucus. Symptoms include shortness of breath and wheezing. Acute bronchitis is usually treated with antibiotics.


Asthma is a chronic illness in which the bronchioles, the tiny branches into which the bronchi are divided, become inflamed and narrow (Figure below). The muscles around the bronchioles contract, which narrows the airways. Large amounts of mucus are also made by the cells in the lungs. People with asthma have difficulty breathing. Their chests feel tight, and they wheeze.

Asthma can be caused by different things, such as allergies. Asthma can also be caused by cold air, warm air, moist air, exercise, or stress. The most common asthma triggers are illnesses, like the common cold.

Asthma is not contagious and cannot be passed on to other people. Children and adolescents who have asthma can still lead active lives if they control their asthma. Asthma can be controlled by taking medication and by avoiding contact with environmental triggers for asthma, like smoking.

Asthma occurs when the bronchioles swell and the muscles around the bronchioles contract.


Pneumonia is an illness that occurs when the alveoli, the tiny sacs in the lungs where gas exchange takes place, become inflamed and filled with fluid. When a person has pneumonia, gas exchange cannot occur properly across the alveoli. Pneumonia can be caused by many things. Infection by bacteria, viruses, fungi, or parasites can cause pneumonia. An injury caused by chemicals or a physical injury to the lungs can also cause pneumonia. Symptoms of pneumonia include cough, chest pain, fever, and difficulty breathing. Treatment depends on the cause of pneumonia. Bacterial pneumonia is treated with antibiotics.

Pneumonia is a common illness that affects people in all age groups. It is a leading cause of death among the elderly and people who are chronically and terminally ill.


Tuberculosis (TB) is a common and often deadly disease caused by a genus of bacterium called Mycobacterium. Tuberculosis most commonly attacks the lungs but can also affect other parts of the body. TB is a chronic disease, but most people who become infected do not develop the full disease. Symptoms include a cough, which usually contains mucus and coughing up blood.

The TB bacteria are spread in the air when people who have the disease cough, sneeze, or spit, so it is very contagious. To help prevent the spread of the disease, public health notices, such as the one pictured below (Figure below), remind people how to stop the spread of the disease.

A public health notice from the early 20th century reminded people that TB could be spread very easily.


Lung cancer is a disease in which the cells found in the lungs grow out of control. The growing mass of cells can form a tumor that pushes into nearby tissues. The tumor will affect how these tissues work. Lung cancer is the most common cause of cancer-related death in men, and the second most common in women. It is responsible for 1.3 million deaths worldwide every year (Figure below). The most common symptoms are shortness of breath, coughing (including coughing up blood), and weight loss. The most common cause of lung cancer is exposure to tobacco smoke.

The inside of a lung showing cancerous tissue.


Emphysema is a chronic lung disease caused by the breakdown of the lung tissue. Symptoms of emphysema include shortness of breath, especially during exercise, and chronic cough, usually due to cigarette smoking, and wheezing, especially during expiration. Damage to the alveoli (Figure below), is not curable. Smoking is the leading cause of emphysema.

The lung of a smoker who had emphysema (left). Tar, a sticky, black substance found in tobacco smoke, is evident. Chronic obstructive pulmonary disease (right), is a tobacco-related disease that is characterized by emphysema.

Causes of Respiratory Diseases

Many respiratory diseases are caused by pathogens. A pathogen is an organism that causes disease in another organism. Certain bacteria, viruses, and fungi are pathogens of the respiratory system. The common cold and flu are caused by viruses. The influenza virus that causes the flu is pictured below (Figure below). Tuberculosis, whooping cough, and acute bronchitis are caused by bacteria. The pathogens that cause colds, flu, and TB can be passed from person to person by coughing, sneezing, and spitting.

This is the influenza virus that causes the swine flu, or H1N1. The Center for Disease Control and Prevention recommends that children between the ages of 6 months and 19 years get a flu vaccination each year.

Pollution is another common cause of respiratory disease. The quality of the air you breathe can affect the health of your lungs. Asthma, heart and lung diseases, allergies, and several types of cancers are all linked to air quality. Air pollution is not just found outdoors; indoor air pollution can also be responsible for health problems.

Smoking is the major cause of chronic respiratory disease as well as cardiovascular disease and cancer. Exposure to tobacco smoke by smoking or by breathing air that contains tobacco smoke is the leading cause of preventable death in the United States. Regular smokers die about 10 years earlier than nonsmokers do. The Centers for Disease Control and Prevention (CDC) describes tobacco use as "the single most important preventable risk to human health in developed countries and an important cause of [early] death worldwide."


  • asthma: Illness in which the bronchioles are inflamed and become narrow.
  • bronchitis: Inflammation of the membrane lining of the bronchial tubes of the lungs.
  • emphysema: Chronic lung disease caused by the breakdown of the lung tissue.
  • lung cancer: Disease in which the cells found in the lungs grow uncontrollably.
  • pathogen: Organism that causes disease.
  • pneumonia: Illness that occurs when the alveoli become inflamed and filled with fluid.
  • tuberculosis : Lung disease caused by a genus of bacterium called Mycobacterium.


  • Common diseases and conditions affecting the respiratory system include asthma, bronchitis, lung cancer, tuberculosis, and emphysema.
  • Pollution, smoking, and pathogens can also contribute to diseases of the respiratory system.


Use the resource below to answer the questions that follow.

  1. What is acute bronchitis? What effect does acute bronchitis have on the respiratory system?
  2. What is pneumonia? What is the effect of pneumonia on the body? What can cause this condition?
  3. What can viral infections of the upper respiratory tract make you susceptible to?
  4. Infections of the respiratory system can cause a decrease in the bodies ability to obtain oxygen. What effects can this have on other areas of the body?


  1. How does asthma affect the lungs?
  2. Identify two things besides smoking that can cause a respiratory disease.

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