The Lungs and the Respiratory System
The respiratory system, including the lungs, brings air into the body. The oxygen in the air travels from the lungs through the bloodstream to the cells in all parts of the body. The cells use the oxygen as fuel and give off carbon dioxide as a waste gas. The waste gas is carried by the bloodstream back to the lungs to be eliminated or exhaled. The lungs accomplish this vital process - called gas exchange - using an automatic and quickly adjusting control system.
The Lungs at Work
In addition to gas exchange, the lungs and the other parts of the respiratory system have important jobs to do related to breathing. These include:
- Bringing all air to the proper body temperature.
- Moisturizing the inhaled air for necessary humidity.
- Protecting the body from harmful substances by coughing, sneezing, filtering or swallowing them, or by alerting the body through the sense of smell.
- Defending the lungs with:
- cilia - microscopic hairs along the air passages
- phlegm (mucus or sputum) - a moving carpet of phlegm collects dirt and germs inhaled into the lungs and moves them out to be coughed up or swallowed
- macrophages - scavenger cells in the lungs that literally eat up dirt and germs invading the lungs
Warning Signs of Lung Disease
The most frequent warning signs of lung disease are listed below. If you are experiencing any of these symptoms, discuss them with your doctor as soon as possible.
- Chronic Cough - Any cough that has lasted a month is chronic. This is an important early symptom indicating something is wrong with your breathing system, regardless of your age.
- Shortness of Breath - Shortness of breath that continues after a brief rest following normal exercise, or comes after little or no exertion, is not normal. Labored or difficult breathing, the feeling that it is hard to draw air into your lungs or breathe it out, is also a warning sign.
- Chronic Phlegm Production - Phlegm, or sputum, is produced by the lungs as a defense response to infection or irritants. If your phlegm or mucus production has lasted a month, this could indicate an underlying problem.
- Wheezing - Noisy breathing or wheezing is a sign that something unusual is blocking the airways of your lungs or making the airways too narrow.
- Coughing Up Blood (Hemoptysis) - If you are coughing up blood, the blood may be coming from your lungs or upper respiratory tract. Whatever the source of the blood, it signals the onset of a health problem.
- Frequent Chest Colds - If you have more than two colds a year, or if one lasts more than two weeks, you may have an underlying disorder.
What do these symptoms mean?
Experts agree that your lungs are not healthy if you have any of these symptoms. You must have them checked out by your doctor. If you wait for symptoms to become severe, you have already lost valuable treatment time. Taking care of mild symptoms can actually be to your advantage.
Even if you have only one of the symptoms of lung disease - chronic cough, shortness of breath or difficult breathing, phlegm, wheezing, or frequent chest colds - you should see your doctor. Most lung conditions can be helped by treatment and can even be reversed if caught early.
Your doctor will usually use very simple tests to determine if you have a lung disease. He or she will take a medical history and give you a complete physical examination. Your examination may include some simple laboratory tests like a chest x-ray, blood tests, a phlegm (sputum) examination, and a pulmonary function test, which is a painless procedure that shows the doctor how well your lungs work when you breathe. Exercise testing may also be done to examine the body's response to exertion or physical activity.
Health authorities advise a tuberculosis (TB) skin test for various groups of people, including all persons who are HIV-positive, meaning that they have tested positive for the human immunodeficiency virus that causes AIDS. Since the TB test reaction may be misleading in AIDS, a chest x-ray and complete physical exam may be recommended even if the tuberculin test is negative.
Based on information gathered through these quick and basic tests, your doctor will decide which lung disease, if any, exists. Then, appropriate treatment can be started.
Common Lung Hazards
Any substance that is breathed in affects what happens to the lungs. Many of these substances can be hazardous and threaten the lungs' ability to work properly. Such hazards may include:
- Cigarette Smoking - The major cause of chronic obstructive pulmonary (note the term pulmonary refers to the lungs) disease (COPD) and lung cancer is cigarette smoking. When someone inhales cigarette smoke, irritating gases and particles cause one of the lungs' defenses - the cilia - to slow down. Even one puff on a cigarette slows the cilia, weakening the lungs' ability to defend themselves against infections. Cigarette smoke can cause air passages to close up and make breathing more difficult. It causes chronic inflammation or swelling in the lungs, leading to chronic bronchitis. And cigarette smoke changes the enzyme balance of the lungs, leading to destruction of lung tissue that occurs in emphysema. Macrophages - scavenger cells in the lungs - are also impaired.
- Triggers of Asthma - Asthma, the temporary blocking of the small passages of the lungs, has many possible triggers and can be life-threatening. Infections, lung irritants, cold weather, allergies, overexertion, excitement, inherited factors, even workplace chemicals and other irritants, play a part in this disease.
- Tuberculosis (TB) - Tuberculosis is caused by a bacterium spread by the coughing or sneezing of a person who has active TB germs in his or her phlegm (sputum). Most people who develop TB today were infected years ago when the disease was widespread. Years or decades later, if the natural defense systems of people's bodies begin to weaken, the barriers they built up around the germs begin to crumble, and the TB germs escape and multiply. Such waiting-to-attack infection can become real illness when a person's defenses are weakened by HIV (Human Immunodeficiency Virus) infection or other illnesses such as cancer.
- Occupational Hazards - Substances you breathe at work can cause lung trouble, too. Workers who are exposed to occupational hazards in the air - dusts like those from coal, silica, asbestos, or raw cotton and metal fumes or chemical vapors - can develop lung disease, including occupational asthma.
- Virus, Fungus, Bacterium (other than TB) - Hundreds of germs like these are carried in the air at all times. If they are inhaled into the lungs, the germs can cause colds, influenza, pneumonia, and other respiratory infections. When these germs lodge in your lungs, your breathing patterns can be disrupted, and you can become ill. Some of these illnesses can be prevented with vaccination.
- Air Pollution - Particles and gases in the air can be a source of lung irritation. Do whatever you can to reduce your exposure to air pollution. Refer to radio or television weather reports or your local newspaper for information about air quality. On days when the ozone (smog) level is unhealthy, restrict your physical activity to early morning or evening because smog is increased in sunlight. When pollution levels are dangerous, limit activities as necessary. People with chronic heart and lung disease should remain indoors.
How Can You Protect Your Lungs and Prevent Lung Disease?
Controlling and preventing lung disease needs everyone's attention. Learn to recognize the symptoms of lung disease, such as those described in this pamphlet. If you have any of these symptoms, get medical attention as soon as possible.
You, your family members and friends need to protect your lungs. Here's how:
Don't smoke. Quitting smoking is the best protection you can give your lungs and reduces your risk of lung disease.
Be honest. Understand that chronic cough, shortness of breath and other lung symptoms are not normal.
Take action. Bring any lung disease symptom to your doctor's attention early. Then follow the doctor's advice.
Avoid lung hazards. Secondhand cigarette smoke, air pollution, and lung hazards at work can cause some lung diseases.
Think about prevention. Lung diseases like influenza (flu) and pneumococcal pneumonia can be prevented with vaccination. Get immunized if you are in a high risk group, which includes people over 65 or anyone with a chronic health problem such as heart disease, lung disease and diabetes.
Remember - early detection of lung disease is the key to prompt and successful treatment.
If you would like more information about the lungs and the prevention of lung disease, contact your local or provincial Lung Association. The Lung Association has additional information about lung diseases and related topics including: