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Asthma - An Allergy

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					Asthma - An Allergy
Undoubtedly, allergies often cause asthma. The terms asthma and allergy
are often used as synonyms by laymen and in medical terminology.
Unfortunately, only a few cases of asthma are really caused by allergies.
The term allergy is difficult to define. Allergy basically means "to
react differently". As a matter of fact, many asthmatic patients react
differently to various kinds of inhaled substances than do healthy
people. Antibodies, which are usually significant in the protection from
pathogenic agents, initiate a fateful chain of reactions in the case of
asthma.
Allergic asthma due to pollen is a good example. Whereas about 90 percent
of the population can inhale large amounts of pollen from grasses and
ragweed, which bloom during spring and autumn, the remaining 10 percent
of the population suffer from hay fever or pollen asthma. The link
between the nose and the airways is obvious. Anyone who suffers from hay
fever, called pollinosis in medical terminology, will complain about the
discomfort it causes. While everyone else enjoys the first signs of
summer, the sunshine, the warmth and the blooming of the meadows, the
person suffering from hay fever hides behind the drawn blinds because
otherwise, his eyes run and the itching of the eye becomes intolerable. A
person suffering from hay fever may also experience a constantly running
nose, difficulty of breathing through the nose and may feel generally ill
although the illness seems to be so harmless.
Nonetheless, the person with hay fever suffers far less than the one with
pollen asthma. Pollen asthma affects a part of the bronchial system,
which is far more important for breathing than is the nose. It is not
known why the disease affects the nose in one person and the bronchial
system in another. Unfortunately, children who suffer from hay fever
while still in school develop asthma as adults. Causes for this
development are unknown.
How does the seemingly innocuous pollen cause asthma?
Pollen is usually too large to infiltrate the bronchial wall as a whole.
Rather, the bronchial mucosa dissolves the pollen into protein particles
small enough to pass through the epithelium (a membranous tissue composed
of cell layers forming the covering of most internal and external
surfaces of the body and its organs). These pollen particles then
encounter cells in the bronchial mucosa, which develop antibodies against
it. It would appear that this formation of antibodies to trap the pollen
particles is normal. Unfortunately, the antibody struggles with the
intruding pollen particle without success. The formation of allergy
antibodies initiates a reaction, which is more harmful to the body than
if nothing had happened. The struggle between the intruding allergens and
the antibodies formed by the body takes place on the membrane of so-
called mast cells, which are composed of dangerous substances. Mast cells
take part in the body's allergic response. They can be found in most body
tissues, but are predominantly abundant in connective tissue, such as the
bronchial mucosa. In an allergic response, an allergen stimulates the
release of antibodies, which attach themselves to mast cells. Following
subsequent allergen exposure, the mast cells release substances such as
histamine (a chemical which causes allergic symptoms) into the tissue.
These substances lead to a spasm of the bronchial muscles, make the small
vessels in the bronchial mucosa permeable, allow blood plasma to escape
into the tissue and lead to the production of extremely viscid bronchial
mucus.
Michael Russell Your Independent guide to Allergies

				
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