What Happens During an Asthma Attack?

Tracing the Biological Processes in Order to Stop Them

Young man using inhaler
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The immune system—or, more specifically, the abnormal response of the immune system—is at the heart of respiratory symptoms associated with asthma. When exposed to certain triggers, the immune system will overact and release chemicals into the bloodstream that cause the lungs to function abnormally.

Asthma attacks are characterized by three distinct features:

  • The tightening of muscles in the air passages, known as bronchoconstriction, by which less air is able to enter the lungs
  • The excessive production of mucus which clogs the air passages
  • The inflammation ​of the air passages as a result of the abnormal immune response

These physiological actions lead to the wheezing, coughing, chest tightness, and shortness of breath experienced during an asthma attack.

Causes of Bronchoconstriction

The normal size of the air passages is regulated by the autonomic nervous system. This is the branch of the nervous system responsible for reflexes.

The stimulation of nerve endings (by dust, cold air, or other asthma triggers) can instigate the release of a chemical known as acetylcholine. In persons with asthma, acetylcholine can act on the postjunctional cells in the smooth muscles of the lungs, causing bronchial spasms and the overproduction of mucus.

Causes of Inflammation

Inflammation is caused by a slightly different process. In people with normally functioning immune systems, the appearance of any foreign particle will be met by an antigen-presenting cell (APC). This is the cell that the body uses to "check out" a particle and determine whether it is safe or not.

In people with asthma, the APC will mistakenly identify the particle as a threat and immediately transform into a defensive cell called TH2. The role of TH2 is to signal the immune system to defend itself, which it does with inflammation.

The consequence of lung inflammation in the absence of disease can be profound, leading to:

  • The enlargement of mucosal cells and the overproduction of mucus
  • The thickening of airway walls and the restriction of air flow
  • The hyperreactivity of the airway tissues, further triggering spasms

If left untreated, ongoing attacks can lead to airway remodeling by which the progressive scarring of lung tissue leaves permanent, irreversible damage.

Preventing Asthma Attacks

While the best treatment for asthma is the avoidance of asthma triggers, this is not always possible or reasonable. Medications, therefore, are commonly prescribed to either manage symptoms or avert attacks.

Among the currently available options:

  • Rescue medications provide fast relief of bronchial spasms and breathing restriction by relaxing the smooth muscles of the airways.
  • Inhaled and oral steroids prevent symptoms by tamping down the immune response and reducing inflammation.
  • Long-acting bronchodilators are used in combination with other drugs to provide better asthma control.
  • Anticholinergics are medications that provide relief by blocking acetylcholine receptors.

Identifying both the triggers of an attack and the medications best able to stop them are the first steps to achieving durable control of asthma symptoms.

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Article Sources
  • Jiang, L.; Diaz, P.; Best, T. et al. "Molecular characterization of redox mechanism in allergic asthma." Annal Allergy Asthma Immunol. 2014; 113(2):137-42. DOI: 10.1016/j.anai.2014.05.030.