IMM250 Paper - University of Toronto Department of Immunology IMM250 Immunity and Infection Asthma Paula Martins 990297166 Dr Clemenza Dr Gommerman

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University of Toronto Department of Immunology IMM250: Immunity and Infection Asthma Paula Martins 990297166 March 22, 2001 Dr. Clemenza Dr. Gommerman Dr. Philpott
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Asthma is a common chronic inflammatory disease affecting the bronchi, also known as the air passages to and from the lungs 1 . Characterized by recurrent attacks of breathlessness, wheezing, coughing and shortness of breath, asthma symptoms vary in severity and frequency from person to person 1 . These symptoms and attacks occur after exercise or exposure to allergens and irritant fumes. During an asthma attack, inflammatory responses cause the lining of the bronchial tubes to swell, narrowing the airways, reducing the flow of air into and out of the lungs 2 . Reoccurring asthma attacks and symptoms frequently cause sleeplessness, daytime fatigue and reduced activity levels. Asthma affected over 300 million people worldwide and caused 255, 000 deaths in 2005 1 . Despite this, Asthma prognosis is often positive and available therapies are generally successful in controlling asthma symptoms and attacks 3 . This paper will examine this chronic disease and how affects those suffering from it. Current Knowledge about Asthma Although asthma is prevalent in many parts of the world and affects many people, the exact cause of the disease is unknown 3 . A combination of environmental and genetic factors seems to be the current accepted theory 5 . Medical professionals classify asthma in 2 ways: type of asthma and level of severity 4 . The more common type is extrinsic asthma, comprising 90% of cases 4 . Intrinsic asthma is less common comprising only 10% of cases 4 . This paper will focus on extrinsic asthma unless otherwise specified. Also known as allergic asthma, extrinsic asthma is caused by an over-reaction of the immune system to a foreign particle such as dust mites, dander and pollen often referred to as allergens or
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antigens 4 . This immune response results in the production of B cells that prime mast cells with Immunoglobin E (IgE) antibodies 6 . Contact with the same allergen causes the IgE primed mast cells to release granules such as histamine and cytokines, which generally attack viruses and bacteria 6 . These granules cause the typical symptoms of asthma such as wheezing, breathlessness and coughing 6 . Intrinsic asthma is not related to allergens and is instead caused by inhalation of cold air, smoke and particular fumes, as well as stress and exercise 4 . This causes irritation in the muscles of the bronchi leading to symptoms similar to extrinsic asthma. Intrinsic asthma typically develops in adults over the age of 30 4 . Levels of severity in those affected by asthma vary significantly from person to person. There are four levels of severity: intermittent, where the frequency of symptoms is less than twice per week; mild persistent, where the frequency of symptoms is more than twice per week, but not daily; moderate persistent, where the symptoms occur daily and severe persistent, where symptoms occurs numerous times per day
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This note was uploaded on 12/05/2011 for the course SOC SOC365 taught by Professor Kristawhitehead during the Fall '10 term at University of Toronto- Toronto.

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IMM250 Paper - University of Toronto Department of Immunology IMM250 Immunity and Infection Asthma Paula Martins 990297166 Dr Clemenza Dr Gommerman

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