Asthma is a condition in which the airways of the lungs – the trachea, bronchial tree, and bronchi; become inflamed and narrowed due to increased sensitivity to various stimuli. As a result, there is an overproduction of mucous and a decrease in the ability of air to flow through the narrowed passages of the lungs. This causes a subsequent reduction in the amount of oxygen entering the body. Wheezing and a feeling of shortness of breath are the most common asthma symptoms.  While the exact cause of asthma is unknown, it is believed to be the result of a genetic component as well as environmental factors.

Asthma occurs in two forms  – acute and chronic. Acute asthma, commonly known as an ‘asthma attack’, is an episodic event that occurs due to an asthma trigger. Chronic asthma develops due to changes that occur from prolonged inflammation.

Acute Form of Asthma

When a patient comes into contact with an asthma trigger, a chain reaction of events occur that leads to an asthma attack. The exposure to the trigger will cause the muscles that surround the airways to “clamp down” or contract, thus narrowing the spaces for air to travel through.

Chronic Form of Asthma

It is believed that patients always have some degree of inflammation in the lungs that make them more sensitive triggers. Chronic inflammation over time can lead to changes in the structures of the lungs and increased mucous production. Proper control of asthma can limit these effects.

Asthma triggers include physical exertion; infection; environmental factors (cold air, high altitude); particulate irritants (smoking, perfume, cleaning agents, etc); emotional factors; allergies (pollen, mold, dust, food allergies, pet allergies, etc); cold air; heartburn; and the use of certain medications such as Non-steroidal Anti-inflammatory Drugs (NSAID’s). Triggers can induce either inflammation and/or constriction of the airways.

Even healthy individuals can experience constriction of the bronchial tree due to too much exercise. This is referred to as exercise-induced asthma bronchoconstriction (EIB) or exercise-induced asthma (EIA). There are medications that can be taken before and after exercise in order to reduce the wheezing.

Development of Asthma

There are a number of risk factors that can lead to the development of asthma in an individual. Asthma can affect a person at any age but typically begins in youth. This is due to the increased vulnerability of the lungs and immune system to the environment during the developmental years.

The development of asthma in response to the environment and allergies are closely linked to Th1-type, Th2-type, and IgE immune responses. Th1-type immune responses are linked to fighting infection while Th2-type responses are more active leading to allergies and asthma. Immunoglobulin E (IgE) responses are linked to allergies. IgE will bind to the allergen and then to a mast cell, which causes the release of Histamine, which in turn causes inflammation and excess mucous production.