JACOPIN / SCIENCE PHOTO LIBRARY JACOPIN / SCIENCE PHOTO LIBRARY
ASTHMA, DRAWING Asthma attack. Illustration of an asthma attack. Following the sensitization phase, contact with the allergen will immediately trigger an asthma attack. The plasma cells which have recognized the allergen release histamine and leukotrienes, causing the bronchiole muscles to contract (bronchospasm), the blood vessels to dilate (oedema), and mucus to be secreted. At the same time, dendritic cells in the ganglions present the allergen to the lymphocytes which secrete cytokines, activating eosinophilic leukocytes in the bone marrow. Via the circulatory system, these granulocytes travel to the bronchial mucosa where they release proteins which damage the epithelial tissue of the bronchial lumen.
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