What Is COPD?
COPD, or chronic obstructive pulmonary
(PULL-mun-ary) disease, is a progressive disease that makes it hard to breathe.
"Progressive" means the disease gets worse over time.
COPD can cause
coughing
that produces large amounts of mucus (a slimy substance), wheezing, shortness
of breath, chest tightness, and other symptoms.
Cigarette smoking is the leading cause of COPD. Most
people who have COPD smoke or used to smoke. Long-term exposure to other lung
irritants, such as air pollution, chemical fumes, or dust, also may contribute
to COPD.
Overview
To understand COPD, it helps to understand
how
the lungs work. The air that you breathe goes down your windpipe into tubes
in your lungs called bronchial tubes or airways.
Within the lungs, your bronchial tubes branch into
thousands of smaller, thinner tubes called bronchioles. These tubes end in
bunches of tiny round air sacs called alveoli (al-VEE-uhl-eye).
Small blood vessels called capillaries run through
the walls of the air sacs. When air reaches the air sacs, the oxygen in the air
passes through the air sac walls into the blood in the capillaries. At the same
time, carbon dioxide (a waste gas) moves from the capillaries into the air
sacs. This process is called gas exchange.
The airways and air sacs are elastic (stretchy).
When you breathe in, each air sac fills up with air like a small balloon. When
you breathe out, the air sacs deflate and the air goes out.
In COPD, less air flows in and out of the airways
because of one or more of the following:
- The airways and air sacs lose their elastic
quality.
- The walls between many of the air sacs are
destroyed.
- The walls of the airways become thick and
inflamed.
- The airways make more mucus than usual, which
tends to clog them.
Normal Lungs and Lungs With COPD
Figure A shows the location of the
lungs and airways in the body. The inset image shows a detailed cross-section
of the bronchioles and alveoli. Figure B shows lungs damaged by COPD. The inset
image shows a detailed cross-section of the damaged bronchioles and alveolar
walls.
In the United States, the term "COPD" includes two
main conditionsemphysema (em-fi-SE-ma) and
chronic
bronchitis (bron-KI-tis). (Note: The Diseases and Conditions Index article
about bronchitis discusses both acute and chronic bronchitis.)
In emphysema, the walls between many of the air sacs
are damaged, causing them to lose their shape and become floppy. This damage
also can destroy the walls of the air sacs, leading to fewer and larger air
sacs instead of many tiny ones. If this happens, the amount of gas exchange in
the lungs is reduced.
In chronic bronchitis, the lining of the airways is
constantly irritated and inflamed. This causes the lining to thicken. Lots of
thick mucus forms in the airways, making it hard to breathe.
Most people who have COPD have both emphysema and
chronic obstructive bronchitis. Thus, the general term "COPD" is more
accurate.
Outlook
COPD is a major cause of disability, and it's the
third leading cause of death in the United States. More than 12 million people
are currently diagnosed with COPD. Many more people may have the disease and
not even know it.
COPD develops slowly. Symptoms often worsen over
time and can limit your ability to do routine activities. Severe COPD may
prevent you from doing even basic activities like walking, cooking, or taking
care of yourself.
Most of the time, COPD is diagnosed in middle-aged
or older people. The disease isn't passed from person to personyou can't
catch it from someone else.
COPD has no cure yet, and doctors don't know how to
reverse the damage to the airways and lungs. However, treatments and lifestyle
changes can help you feel better, stay more active, and slow the progress of
the disease.
Revised June 2010 |