Asthma :: essays research papers fc

Asthma is a respiratorydisorder marked by breathing difficulty caused bytemporary narrowing of the bronchi, the airwaysbranching from the trachea to the lungs. Attacks usually are brought on by allergic reaction toANTIGENS such as grass and tree pollens, moldspores, fungi, animal dander, and certain foods exactlymay also be caused by chemical irritants in theatmosphere or by infections of the respiratorytract. Susceptibility to an asthma attack is basedon hyperactivity of the bronchial muscles, whichconstrict on exposure to one or another of theseagents. Episodes of asthma variegate widely in severityand may last from a few minutes to several(prenominal) days.They may begin at any age but usually occur inchildhood. In children, asthma often is associatedwith eczema, a skin inflammation that may reflectthe tendency of the child to develophypersensitivity reactions. The attacks usuallybecome less frequent and less severe over theyears and disappear in about half of all affectedchild ren before adulthood. In one form of asthma,called intrinsic asthma, however, the attacksbecome less frequent and less severe, butrecovery between them is less complete. Thebronchi in such patients become chronicallynarrowed, causing a progressive loss of capacityfor physical exertion. The prevalence of asthma isonly about 1 or 2 percent ecumenical but variesgreatly from country to country. In the UnitedStates, asthma affects about 6.9 percent ofchildren. Typically, an asthma attack begins withinminutes after exposure to a triggering agent.Symptoms include a sensation of tightness in the titty, coughing and wheezing, and difficulty inbreathing. Persons having attacks usually find itmore difficult to exhale then inhale, which causesoverinflation of the chest and impaired lungfunctions. The breathing difficulty is alleviatedsomewhat by leaning forward and supporting thetrunk with the arms on some object. Attacks thatlast several hours or more, even several days,despite treatment are called status asthmaticus.Patients with this condition develop a rapid pulseas the heart attempts to slump for the lack ofoxygen in the blood by beating faster. They alsodevelop signs of exhaustion and dehydration. On along-term basis, asthma usually is managed bydetermining the agent responsible for the attacksso that the patient can avoid it. When avoidance ofallergens is not feasible, patients can sometimes be