Study GuideMicrobiology–Disorders of the Immune System1.Hypersensitivity ReactionsNot all immune system activity is helpful. In some cases, immune responses themselves causedisease. These conditions are calledhypersensitivity reactions—states in which the immunesystem reactstoo strongly or inappropriately. Hypersensitivities may be caused byantibodiesorimmune cells, and they can lead to tissue injury or even death. Some immune disorders also involveimmunodeficiency, where parts of the immune system fail to function properly.1.1When Protection Turns HarmfulUnder normal conditions, the immune system protects the body from microorganisms and otherforeign substances. However, if the immune response becomesexcessive or misdirected, ahypersensitivity reaction occurs.•Damage usually happensafter antigens interactwith:oAntibodies, oroSensitizedT-lymphocytes•Thetype of immune component involveddetermines the nature and timing of the reaction.1.2Two Major Types of HypersensitivityHypersensitivity reactions are grouped intoimmediateanddelayedforms.Immediate Hypersensitivity•Involvesantibodies•Developswithin minutes•Includes:oAnaphylaxisoAllergic reactionsoCytotoxic reactionsoImmune complex reactionsPreview Mode
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