Bronchoconstriction is the constriction of the airways in the lungs due to the tighting of surrounding smooth muscle, with consequent coughing, wheezing, and shortness of breath. The heart and lungs (from an older edition of Grays Anatomy) The lung is an organ belonging to the respiratory system and interfacing to the circulatory system of air-breathing vertebrates. ... Smooth muscle is a type of non-striated muscle, found within the walls of hollow organs; such as blood vessels, bladders, uteri. ...

Causes

The condition has a number of causes, the most common being asthma and exercise, and allergies. The word exercise can mean the following: A setting in action or practicing. ... This article needs to be cleaned up to conform to a higher standard of quality. ...

Exercise-induced bronchoconstriction

More generally termed exercise-induced asthma, the preferred and more accurate term exercise-induced bronchoconstriction better reflects underlying pathophysiology. It is also preferred due to the former term giving the false impression that asthma is caused by exercise. Pathophysiology is the study of the disturbance of normal mechanical, physical, and biochemical functions that a disease causes. ...

In a patient with EIB, exercise initially follows the normal patterns of bronchodilation. However, by three minutes, the constriction sets in, which peaks at around 10-15 minutes, and usually resolves itself by an hour. During an episode of this type of bronchorestriction, the levels of inflammatory mediators, particularly leukotrienes, histamine, and interleukin, increase. TH2-type lymphocytes are activated, with an increase in T cells expressing CD25 (IL-2R), and B cells expressing CD 23, causing increased production of IgE. After exercise, the conditions will fade within one to three minutes. In most sufferers of EIB, this is followed by a refractory period, of generally less than four hours, during which if exercise is repeated, the bronchorestriction is less emphasised. This is probably caused by the release of prostaglandins. Histamine is a biogenic amine chemical involved in local immune responses as well at regulating physiological function in the gut and acting as a neurotransmitter. ... Interleukins are a group of cytokines that are expressed by white blood cells (leukocytes, hence the -leukin) as a means of communication (inter-). The function of the immune system depends in a large part on interleukins, and rare deficiencies of a number of them have been described, all featuring autoimmune... A lymphocyte is a type of white blood cell involved in the human bodys immune system. ... T cells are a subset of lymphocytes that play a large role in the immune response. ... B cells are lymphocytes that play a large role in the humoral immune response (as opposed to the cell-mediated immune response). ... Immunoglobulin E (IgE) is an antibody from the gamma class of globulin blood proteins. ... A prostaglandin is any member of a group of lipid compounds that are derived from fatty acids and have important functions in the animal body. ...

The underlying cause of this type of bronchoconstriction appear to be the large volume of cool, dry air inhaled during strenuous exercise. The condition appears to worsen when the air inhaled is more fully humidified and closer to body temperature. Thermoregulation is the ability of an organism to keep its body temperature within certain boundaries, even when temperature surrounding is very different. ...

This specific condition, in the general population, can vary between 7 and 20 percent. This increases to around 80 percent in those with symptomatic asthma. In many cases, however, the constriction, even during or after strenuous exercise, is not clinically significant.

Allergen-induced bronchoconstriction

While a different cause, this has very similar symptoms, namely the immunological reaction involving release of inflammatory mediators.

Inhalation of allergens in sensitized subjects develops into bronchorestriction within 10 minutes, reaches a maximum within 30 minutes, and usually resolves itself within one to three hours. In some subjects, the constriction does not return to normal, and recurs after three to four hours, which may last up a day or more. The first is named the early asthmatic response, and the latter the late asthmatic response. An allergen is any substance (antigen), most often eaten or inhaled, that is recognized by the immune system and causes an allergic reaction. ...

External links

• Bronchoconstriction caused by allergen and exercise