Asthma is a
chronic inflammatory disease of airways, (the small tubes that
carry air in and out of the lungs), characterized by sudden
attacks of labored breathing, chest constriction and coughing
and excess mucous production.
Guidelines for the Diagnosis and
Management of
Asthma—Full Report, 2007 defines asthma as:
Asthma is a
chronic inflammatory disorder of the airways in which many cells
and cellular elements play a role: in particular, mast cells,
eosinophils, T lymphocytes, macrophages, neutrophils, and
epithelial cells. In susceptible individuals, this inflammation
causes recurrent episodes of wheezing, breathlessness, chest
tightness, and coughing, particularly at night or in the early
morning. These episodes are usually associated with widespread
but variable airflow obstruction that is often reversible either
spontaneously or with treatment. The inflammation also causes an
associated increase in the existing bronchial
hyperresponsiveness to a variety of stimuli. Reversibility of
airflow limitation may be incomplete in some patients with
asthma.
Asthma is often linked to allergies, heredity and environment.
Traditionally, asthma was considered to be a condition
characterized by narrowing of airways wherein the patients would
gasp for breath.
In people who have asthma caused by an allergic response,
various airborne allergens or other triggers set off a cascade
of events in the immune system that lead to inflammation and
hyper reactivity in the airways.
In a normal individual, the allergen like
Housedust mite stimulates the production
of antibodies, which destroy the allergen. These antibodies are
produced in amounts sufficient to destroy the allergen.
People with asthma have airways that are almost always red and
sensitive (inflamed). Their airways can react badly when they
have a cold or other viral infection, or when they come into
contact with an asthma trigger (something that sets off their
symptoms). When this happens the muscles around the walls of the
airways tighten and they become narrower.
The lining of the airways swell and often produce thick sticky
mucus. As the airways narrow, the air has to squeeze in and out,
and this is what causes the person with asthma to find it
difficult to breathe.
Asthma symptoms can include coughing, wheezing, shortness of
breath or a tight feeling in the chest.
Triad of asthma are as follows:
1. Airway hyperresponsiveness it is a unique property of
patients of asthma to react to external stimuli.
2. Bronchoconstriction meaning that the muscles that encircle
the airways tighten or go into spasm.
3. Chronic inflammation means that the airways become red,
swollen and narrow.
Excessive mucous production is also present in asthma.
