diaphragm
A sheet of muscle that extends across the bottom of the rib cage. When the diaphragm contracts the chest volume gets larger and the lungs take in air; when the diaphragm relaxes, the chest volume gets smaller and air is pushed out of the lungs.
epiglottis
A flap of connective tissue that closes over the trachea when food is swallowed to prevent choking or inhaling food.
exhalation
Pushing air out of the body through the nose or mouth.
external respiration
The movement of oxygen into the body and carbon dioxide out of the body.
gas exchange
The movement of oxygen across a membrane and into the blood and the movement of carbon dioxide out of the blood.
inhalation
Taking air into the body through the nose and mouth.
internal respiration
The exchange of gases between the blood and the cells of the body.
larynx
Found just below the point at which the pharynx splits into the trachea and the esophagus. Your voice comes from your larynx; air from the lungs passes across thin membranes in the larynx and produces sound; also called the voicebox.
pharynx
A long tube that is shared with the digestive system; both food and air pass through the pharynx.
respiration
The process of getting oxygen into the body and releasing carbon dioxide.
trachea
A long tube that leads down to the chest where it divides into the right and left bronchi in the lungs; also called the windpipe.
Points to Consider
How do you think the health of your respiratory system might affect the health of other body systems?
Lesson 19.2: Health of the Respiratory System
Lesson Objectives
Identify the organs affected by a respiratory disease.
Identify how a respiratory disease can affect the rest of the body.
Describe how asthma affects breathing.
Outline how smoking affects the respiratory system.
Identify what you can do to keep your respiratory system healthy.
Check Your Understanding
What is the role of the respiratory system?
What are some of the organs of the respiratory system?
Introduction
Most of the time your respiratory system works well, and you don’t notice it doing its job. But your respiratory system can sometimes be knocked out of homeostasis. Recall that homeostasis is the balancing act your body performs that keeps conditions in your body stable. Anything that disrupts the respiratory system from doing its job disrupts homeostasis. When homeostasis no longer exists, there is disease. There are many causes of respiratory diseases, and many ways to treat such diseases. In this lesson you will learn about some of the most common respiratory diseases, and what you can do to help avoid them. You will also learn how the use of tobacco disrupts homeostasis, which leads to some of the most serious respiratory diseases.
Respiratory System Disease
In general, diseases that last a short time are called acute diseases. Other diseases can last for a long time, perhaps years. Diseases that last for a long time are called chronic diseases. Both acute and chronic diseases affect 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 bacterial pneumonia. Respiratory diseases are common and may cause illness or death. Some respiratory diseases are caused by bacteria while others are caused by viruses, environmental pollutants such as tobacco smoke, or are hereditary.
Figure 19.6
This boy is suffering from whooping cough (also known as ) which gets its name from the loud whooping sound that is made when the person inhales during a coughing fit.
Bronchitis
Bronchitis is an inflammation of the bronchi. 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 (mucus). Symptoms include shortness of breath and wheezing, which are related to the inflammation of the airways. Acute bronchitis is usually treated with antibiotics.
Chronic bronchitis may not be caused by a bacterium or a virus. Chronic bronchitis is defined as having a cough that produces phlegm, for at least three months in a two-year period. Tobacco smoking is the most common cause of chronic bronchitis, but it can be caused by environmental pollution such as smog and dust. It is generally part of a syndrome called chronic obstructive pulmonary disease (COPD), which we will learn about later. Treatments for bronchitis include antibiotics and steroid drugs to reduce inflammation.
Asthma
Asthma is a chronic illness in which the bronchioles are inflamed and become narrow, as shown in Figure below. The muscles around the bronchioles contract which narrows the airways further. Large amounts of mucus are also made by the cells that line the lungs. A person with asthma has difficulty breathing. Their chest feels tight and they wheeze.
Asthma can be caused by different things such as exposure to an allergen. An allergen is any antigen that is not an infectious organism. Allergens can cause allergic reactions. Common allergens that cause asthma are mold, dust, or pet hair. Asthma can also be caused by cold air, warm air, moist air, exercise, or stress. The most common asthma triggers are viral illnesses such as the common cold. The symptoms of asthma can usually be controlled with medicine. Bronchodilators are drugs that reduce inflammation of the bronchioles allowing air through.
Asthma is not contagious and cannot be passed on to other people. Sometimes people with asthma are afraid that being active could cause them to have an asthma attack. Having asthma does not mean that you have to miss out on being active. Many teens that have asthma are active every day. Asthma cannot be cured, but is treatable with medicines. 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.
Figure 19.7
The two reactions that lead to asthma are when the bronchioles swell and the muscles around the bronchioles contract.
Pneumonia
Pneumonia is an illness in which the alveoli become inflamed and flooded with fluid. Pneumonia is a restrictive respiratory disease. Gas exchange cannot happen properly across the alveoli membranes. 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 in breathing. Treatment depends on the cause of pneumonia. Bacterial pneumonia is treated with antibiotics.
Pneumonia is a common illness which occurs in all age groups, and is a leading cause of death among the elderly and people who are chronically and terminally ill. Vaccines to prevent certain types of pneumonia are available.
Tuberculosis
Tuberculosis (TB) is a common and often deadly infectious disease caused by a genus of bacterium called Mycobacterium. Tuberculosis most commonly attacks the lungs but can also affect other parts of the body. Mycobacteria in the alveoli cause an immune reaction in the body that damages the alveoli. TB is a chronic disease, but most people who become infected do not develop the full disease. The TB Mycobacteria are spread in the air when people who have the disease cough, sneeze or spit. To help prevent the spread of the disease, public health notices, such as the one in Figure below, remind people how to stop the spread of the disease. Currently, drug resistant forms of TB are creating a new challenge for health professionals.
Figure 19.8
A public health notice from the early 20th century reminded people that TB could be spread very easily.
Cancer
Lung cancer is a disease where the cells that line the lungs grow out of control. The growing mass of cells
pushes into nearby tissues and can affect how these tissues work. Lung cancer, which is the most common cause of cancer-related death in men and the second most common in women, is responsible for 1.3 million deaths worldwide every year 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.
Emphysema
Emphysema is a chronic lung disease caused by loss of elasticity of the lung tissue. The surfaces of healthy alveoli are springy and elastic. They stretch out a little when full of air and relax when air leaves them. But the breakdown of the tissues that support the alveoli and the capillaries that feed the alveoli cause the alveoli to become hard and stiff. Eventually the walls of the alveoli break down and the alveoli become larger. When alveoli become larger, the amount of oxygen that can enter the blood with each breath is reduced. Much of the oxygen that gets into the large alveoli cannot be absorbed across the alveoli walls into the blood. Symptoms of emphysema include shortness of breath on exertion (usually when climbing stairs or a hill). Damage to the alveoli, which can be seen in Figure below, is not curable. Smoking is a leading cause of emphysema.
Figure 19.9
The lung of a smoker who had emphysema (left); the black areas are enlarged alveoli and tar, a sticky, black substance found in tobacco smoke is evident, and (right) COPD (Chronic obstructive pulmonary disease), a tobacco-related disease that is characterized by emphysema.
Causes of Respiratory Diseases
Pathogens
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 shown in 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 by spitting.
Figure 19.10
This is the influenza virus that causes the flu; the CDC (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
Air quality is related to several respiratory diseases. Asthma, heart and lung diseases, allergies, and several types of cancers are all linked to air quality. Air pollution can be caused by outdoor pollution or indoor pollution. Outdoor air pollution can be caused by car exhaust fumes, smoke from factories and forest fires, volcanoes, and animal feces. Some of the pollutants of concern include particulates, carbon dioxide, sulfur oxides, and lead. These pollutants contain tiny particles that can get “stuck” in the lining of the respiratory system and irritate the lungs. Indoor air pollution can be caused by tobacco smoke, dust, mold, insects, rodents, and cleaning chemicals.
Lifestyle Choices
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 U.S. 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 premature death worldwide.
Dangers of Smoking
Tobacco use, particularly cigarette smoking, is the single most preventable cause of death in the United States. Cigarette smoking alone is directly responsible for approximately 30 percent of all cancer deaths annually in the United States. The main health risks of using tobacco are linked to diseases of the cardiovascular system and respiratory system. Cardiovascular diseases caused by smoking include heart disease and stroke. Diseases of the respiratory system that are caused by exposure to tobacco smoke include emphysema, lung cancer, and cancers of the larynx and mouth. Cigarette smoking causes 87 percent of lung cancer deaths. Smoking and using tobacco is also linked to the risk of developing other types of cancer such as pancreatic and stomach cancer.
Cigarettes, like the ones shown in Figure below, are a major source of indoor air pollution. Cigarette smoke contains about 4,000 substances, including over 60 cancer-causing chemicals. Many of these substances, such as carbon monoxide, tar, arsenic, and lead, are toxic to the body. Non-smokers can also be affected by tobacco smoke. Exposure to secondhand smoke, also known as environmental tobacco smoke (ETS), greatly increases the risk of lung cancer and heart disease in nonsmokers.
Chronic obstructive pulmonary disease (COPD) is a disease of the lungs in which the airways become narrowed. This leads to a limitation of the flow of air to and from the lungs causing shortness of breath. The limitation of airflow usually gets worse over time. COPD is most commonly caused by smoking. Gases and particles in tobacco smoke trigger an abnormal inflammatory response in the lung. The inflammatory response in the larger airways is known as chronic bronchitis. In the alveoli, the inflammatory response causes the breakdown of the tissues in the lungs, leading to emphysema.
Figure 19.11
Tobacco use, particularly cigarette smoking, is the single most preventable cause of death in the United States.
Keeping Your Respiratory System Healthy
Many of the diseases related to smoking are called lifestyle diseases, diseases that are caused by choices that people make in their daily lives. For example, the choice to smoke can lead to cancer in later life. But, there are many things you can do to help keep your respiratory system healthy. Some of these are listed here:
Avoid Smoking
Never smoking or quitting now are the most effective ways to reduce your risk of developing chronic respiratory diseases such as cancer.
Eat Well, Exercise Regularly, and Get Rest
Eating a healthful diet, getting enough sleep, and being active every day can help keep your immune system strong.
Wash Your Hands
Washing your hands often, and after sneezing, coughing or blowing your nose help to protect you and others from diseases. Washing your hands for 20 seconds with soap and warm water can help prevent colds and flu. Some viruses and bacteria can live from 20 minutes up to 2 hours or more on surfaces like cafeteria tables, doorknobs, and desks. A public health notice that shows people how to prevent the spread of respiratory diseases is shown in Figure below.
Avoid Contact with Others When Sick
Do not go to school or to other public places when you are sick. You risk spreading your illness to other people and getting sicker if you catch something else.
Visit Your Doctor
Getting the recommended vaccinations can help prevent diseases such as whooping cough and flu. Seeking medical help for diseases such as asthma can help control the severity of the disease.
Figure 19.12
is a public health campaign that reminds people of the quickest and easiest ways to avoid spreading respiratory diseases such as colds and the flu.
Lesson Summary
Respiratory diseases are diseases that affect the lungs, bronchial tubes, trachea, nose, and throat. Respiratory diseases can reduce the amount of oxygen that gets into the blood. Asthma is an illness in which the bronchioles are inflamed and become narrow. The muscles around the bronchioles contract which narrows the airways further.
Difficulty in breathing happens because of the inflammation, contraction of the muscles, and the production of mucus by the cells that line the bronchioles. Diseases of the respiratory system that are caused by exposure to tobacco smoke include emphysema, lung cancer and cancers of the larynx and mouth.
Cigarette smoking causes 87 percent of lung cancer deaths. Smoking and using tobacco is also linked to the risk of developing other types of cancer. Avoiding smoking, getting enough exercise, and washing your hands often are three things you can do to help protect your respiratory system from illness.
Further Reading / Supplem
ental Links
http://www.cdc.gov/vaccines/vpd-vac/pertussis/default.htm
http://www.cdc.gov//HealthyLiving/
http://www.cancer.gov/cancertopics/factsheet/Tobacco/cancer http://en.wikipedia.org/wiki/Cigarette_smoking; http://www.cancer.gov/cancertopics/factsheet/Tobacco/cancer
http://www.cancer.gov/cancertopics/factsheet/Tobacco/cancer
http://www.cdc.gov/flu/protect/covercough.htm
Review Questions
Identify the organs that are affected by a respiratory disease.
How might a respiratory disease affect the rest of the body?
How does asthma affects the bronchioles?
Medicines called bronchodilators are used to treat the symptoms of asthma. What action do you think these drugs have on the lungs?
What lifestyle activity has the largest health impact on the respiratory system?
Identify three diseases are linked to tobacco smoking.
Identify three things that can cause a respiratory disease.
What are two things you can do to keep your respiratory system healthy?
CK-12 Life Science Page 50