What is Asthma?


   5.1million people in the U.K. suffer from chronic asthma, that amounts to about one in every seven people.  Asthma is known as a COPD (chronic obstructive pulmonary disease).  It is a chronic, inflammatory disorder, which leads to the spontaneous narrowing of the airways.  Attacks occur due to an allergic reaction, which lead to spasms of the smooth muscle in the bronchial walls (in the lungs).  This constriction leads to the partial or full closing of the airways, and thus the inability to breathe normally.   

   The body’s autonomic nervous system (ANS) provides a natural mechanism to control the diameter of the airways in the lungs, these are overridden in an attack.  The ANS is divided into the parasympathetic and sympathetic nervous systems.  The sympathetic system promotes a ‘fight or flight’ response, and the parasympathetic leads to a ‘rest and digest’ response.  Drugs used to treat asthma try to block the parasympathetic response and activate the sympathetic response.  This is because during sympathetic activity (e.g. fighting or fleeing) the airways need to dilate (/open) in order to get more oxygen into the lungs and around the body.  Therefore, administering a drug, which activates the sympathetic response, will counter the constricting effects of asthma on the airways. 

See the diagram below for positioning of the bronchial tubes in the lungs.


                                                                                                     (taken without permission)

  People who suffer from asthma are hypersensitive to a variety of external stimuli that would usually not lead to bronchi constriction.

  Asthma is not serious when kept under control, it can however lead to loss of lung function if not treated.

  In the early stages of an attack there is often an excess secretion of mucus from the glands in the airways, which can potentially clog the bronchi and bronchioles, thereby, worsening the attack.  In the later stages of an attack inflammation continues, leading to further narrowing of the airways.    



   These are commonly related to some kind of allergic reaction, for example, to pollen or dust mites.  Other common triggers include inhalation of pollution, emotional upset, aspirin, exercise and breathing cold air.



   Periods of coughing, tightness of chest, and wheezing.

During an attack the person has to work a lot harder than normal in order to breathe effectively.  The classic tight chest symptoms are thus explained by this bronchi constriction preventing complete inhalation into the lungs.   The wheezing sounds are caused by turbulent airflow in the narrowed airways.

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