Asthma and Allergies: The Science Inside

95 Pages·2004·2.47 MB·English

XX
H E A L T H Y P E O P L E L I B R A R Y P R O J E C T
Part 1: What is Asthma?
American Association for the Advancement of Science
Asthma and Allergies
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Asthma and
Allergies: The
Science Inside
HEALTHY PEOPLE LIBRARY PROJECT
American Association for the Advancement of Science
Published 2004 by The American Association for the Advancement of Science (AAAS)
1200 New York Avenue, NW
Washington, DC 20005
© Copyright 2004 by AAAS
0-87168-694-5
All rights reserved. Permission to reproduce this document for not-for-profit
educational purposes or for use in a review is hereby granted. No part of this book
may be reproduced, stored in a retrieval system, or transmitted in any form, or by
any means, electronic, mechanical, photocopy, recording, or otherwise, for commercial
purposes without prior permission of AAAS.
This booklet is a product of the Healthy People 2010 Library Initiative funded by a
Science Education Partnership Award (SEPA) from the National Center for Research
Resources at the National Institutes of Health (Grant # 5R25RR15601).
Any interpretations and conclusions contained in this booklet are those of the authors
and do not represent the views of the AAAS Board of Directors, the Council of AAAS,
its membership, or the National Institutes of Health.
T A B L E O F C O N T E N T S
INTRODUCTION: ASTHMA AND ALLERGIES . . . . . . . . . . . . . . . . . . . . . 1
PART 1: WHAT IS ASTHMA? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Healthy breathing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Problems associated with asthma . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
The symptoms of asthma . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
The causes of asthma . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
How asthma affects the body . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
How asthma affects lifestyle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
PART 2: WHAT ARE ALLERGIES? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Healthy immune system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Problems associated with allergies . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
The symptoms of allergies. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
The causes of allergies. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
How allergies affect the body. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
How allergies affect lifestyle. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
PART 3: WHO HAS ASTHMA AND ALLERGIES?. . . . . . . . . . . . . . . . . . 31
Childhood allergies and asthma . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Uneven impact of allergies and asthma . . . . . . . . . . . . . . . . . . . . . . . 35
Societal impact of allergies and asthma . . . . . . . . . . . . . . . . . . . . . . . 37
PART 4: HOW CAN ASTHMA BE TREATED AND PREVENTED?. . . . . . . 41
Diagnosing and treating asthma. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Preventing and controlling asthma. . . . . . . . . . . . . . . . . . . . . . . . . . . 44
The relationship between allergies and asthma. . . . . . . . . . . . . . . . . 49
PART 5: HOW CAN ALLERGIES BE TREATED AND PREVENTED? . . . . . 53
Diagnosing and treating allergies. . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
Preventing and controlling allergies. . . . . . . . . . . . . . . . . . . . . . . . . . 57
PART 6: WHAT DOES RESEARCH TELL US ABOUT ASTHMA AND
ALLERGIES? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
Current lines of research. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
The important role of volunteers . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
CONCLUSION: Let’s Breathe Easy with Asthma and Allergies . . . . . . 71
APPENDIX 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
Sample Asthma Action Plan
Appendix 2: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
Questions to Ask Your Physician about Allergies and Asthma
APPENDIX 3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
Taking Part in Research Studies — Questions to Ask
RESOURCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
BIBLIOGRAPHY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
GLOSSARY. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
INTRODUCTION:
ASTHMA AND ALLERGIES
N
othing is more essential to
our well-being than the ability
to breathe. Most of us breathe
in and out all day long without
even giving it a thought. Yet
millions of people in the United
States are not so lucky. They
suffer from asthma or allergies.
For people with asthma, taking a
breath can be extremely difficult.
For people with allergies, the air
they breathe can be filled with
substances that cause
discomfort or worse.
Asthma is a chronic lung disease An asthmatic, or a person with Asthma
affects 1 out
in which air passages get asthma, responds differently to
of every
inflamed. When this happens, certain substances than a person 20 children.
airways narrow and it is difficult who does not have the disease.
for air to move from the nose and For an asthmatic, these sub-
mouth to the lungs. In the United stances become triggers. Atrig-
States, this disease affects mil- ger is a factor that can bring on
lions of people, many of them the symptoms of asthma or make
children. In fact, asthma is the the condition worse. For an asth-
most common chronic childhood matic, triggers can include house-
disease, affecting 1 out of every hold or industrial chemicals,
20 children. The number of peo- tobacco smoke, dust, changes in
ple with asthma has been weather, and exercise. Exposed
increasing since the 1980s. The to a trigger, an asthmatic might
disease affects people of all ages experience tightness in the chest,
and races and both sexes. coughing, wheezing, and short-
However, asthma is more com- ness of breath.
mon in children than adults. It is
also more common in African Although asthma is common,
Americans and Hispanics than it can be controlled and treated.
1
whites. It is important for an asthmatic
A s t h m a a n d A l l e r g i e s : T h e S c i e n c e I n s i d e
to avoid contact with any trigger specializes in the treatment of
known to cause symptoms. A per- allergies. Before establishing a
son with asthma should get treatment program, an allergist
continuous medical care and see will conduct tests to determine
a physician regularly. A doctor which allergens are triggers for a
can measure lung function and particular patient. The allergist
capacity and recommend medica- may recommend or prescribe med-
tion to reverse and prevent airway ications that can reduce sensitivity
swelling and obstruction. If the to certain substances. Allergen
symptoms are managed well, an immunotherapy can also be used
asthmatic can enjoy a normal life. to reduce sensitivity. A person
undergoing allergen immunothera-
Like asthma, allergies also affect py receives injections containing
millions of people. An allergy is small amounts of the allergen to
the body’s overreaction to which he or she reacts over the
certain substances, called course of several years. This
allergens. An allergic per- treatment helps the person
son responds differently to build immunity to an allergen.
allergens than does a per- Ultimately, this can mean that
son with no allergies. an allergic reaction does not
Some of the most common occur at all.
allergens include dust
mites, cockroach drop- Fortunately, there are many prom-
pings, animal dander, ising areas of research on allergies
grass, insect venom from and asthma. Scientists are work-
stings, medications, and ing to discover what causes asth-
certain foods. An allergic ma and allergies, how to prevent
reaction can range from them from occurring, and how to
sneezing and itching to treat them. But it is also vital that
swelling of the throat and loss of everyone who suffers from asthma
consciousness. As with asthma, or allergies have a basic under-
allergic reactions can be severe standing of these ailments. This
and even fatal. book contains information that
will help asthmatics and allergy
A person with allergies should sufferers take charge of their own
avoid allergens that are known to health so that they can lead full,
cause symptoms. People who have active lives.
experienced severe allergic reac-
tions should be under the care of
an allergist—a physician who
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Part 1: What Is Asthma?
Healthy breathing
Healthy breathing is effortless. A
person who is breathing normally
will not be aware of the process.
Every minute of every day, the
lungs expand and contract 15
times. This process allows the
blood to deliver oxygen to red
blood cells and to take away car-
bon dioxide.
For the exchange of oxygen for
Air enters the nose, where it is carbon dioxide to take place, the
warmed and moistened. Then, it diaphragm, a sheet of muscle
enters the trachea, a single tube that separates the chest from the
that is the beginning point of the abdominal cavity, must contract.
airways. The trachea divides into When the diaphragm contracts,
two narrower tubes called a partial-vacuum effect occurs
bronchi. Each bronchus is a way around the lungs, causing them
into the lungs. As the air travels
through the lungs, it moves
through progressively smaller
tubes called bronchioles. At the
tip of the last bronchiole it enters,
the air comes into contact with
hundreds of millions of tiny air
sacs called alveoli. These sacs
take in oxygen from the air
in exchange for carbon dioxide.
Eventually, the lungs will exhale
the carbon dioxide.
3
A s t h m a a n d A l l e r g i e s : T h e S c i e n c e I n s i d e
particles, the mucus is carried
by cilia (which look like tiny
hairs) from the bottom of the
lungs to the throat. Once the
mucus reaches the throat, it is
either swallowed or coughed
out. If the mucus is not cleared,
In a nonasthmatic person,
the muscles around the viruses, bacteria, and other
In an asthmatic person, the bronchial tubes are relaxed
muscles of the bronchial and the tissue thin, allowing impurities can collect in the
tubes tighten and thicken, for easy airflow.
and the air passages lungs and cause infection or ill-
become inflamed and filled
with mucus, making it ness. Healthy lungs are grayish
difficult for air to move.
pink in color. Lungs that are
damaged by pollutants can
become blackened.
If your breathing is not healthy
or normal, it might be due to
allergies or even asthma.
Allergies have been linked to
asthma, so it is not unusual
to find that a person suffers
from both. These disorders
can be treated, and sometimes
to expand. When the lungs the symptoms can even be
expand, air pressure in the chest prevented. With proper medical
cavity is lower than the air pres- care and changes in behavior or
sure outside. This difference in environment, someone who suffers
pressure causes air from the from allergies or asthma can
outside to fill the lungs. Each breathe comfortably and live
time this happens, approximately an active life.
1 pint of air enters the lungs.
When you exhale, the diaphragm Problems associated
relaxes. When the lungs deflate, with asthma
carbon dioxide is forced out. While
Asthma is a chronic lung disease
this entire process is taking place,
that makes breathing difficult. For
mucus in the air passages is trap-
an asthmatic, breathing becomes
ping any foreign materials that
difficult for a variety of reasons.
have entered your body with the
Airways can become inflamed,
air. After the mucus traps these
restricted, or blocked, so that very
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Part 1: What Is Asthma?
little air can travel to and from these symptoms are usually
the lungs. The air that does get associated with colds or infec-
through these narrowed passages tions. That is why it is important
can cause a high-pitched or to notice when they reoccur for
whistling sound called wheezing. no apparent reason. When this
The chest can also become tight happens, it could mean that you
or constricted, requiring the per- have asthma. Although asthma
son to use more effort just to symptoms might resemble cold
breathe. This is called labored symptoms, they must be treated
breathing. differently.
If a lot of viscous (thick) mucus is A viral infection,
released in the airways, it can such as a cold, might
produce coughing. As the body make it hard to
tries to clear the mucus from the sleep at night for a
airways, a rattling sound often few days. Nighttime
occurs. If the airways become asthma is very dif-
plugged with mucus, the lungs ferent. It can make
can fully or partially collapse. getting proper rest
This collapse can be caused by nearly impossible for
a number of conditions, from a long period of
prolonged bed rest to pneumonia, time. Some asthmat-
and can be seen on a chest X ray. ics have symptoms
Unfortunately, when a collapsing every night. People
lung is found—especially in com- with nighttime asth-
bination with a rattling sound ma often have to
heard in the chest—asthma can sleep sitting upright
be misdiagnosed as bronchitis or in order to breathe.
even pneumonia. Antibiotics are If these symptoms
often prescribed for bronchitis are disregarded as
and pneumonia, but these med- cold symptoms, then
ications are not effective against they will not be treated properly.
asthma. A serious lack of rest can have
dangerous consequences, especial-
ly for a developing child.
The symptoms of asthma
People with asthma experience Symptoms of asthma are usually
symptoms that can include cough- measured by their severity, fre-
ing, wheezing, congestion, and quency, and response to treat-
tightness in the chest. Most of ment. The National Institutes of
5