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12 Cards in this Set
- Front
- Back
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defintiion |
a damaging immune response by the body to a substance, espcially a particular food, poller, fur or dust, to which it has become hypersentivetyp |
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types of allergy |
Type 1 - IgE mediated (allergy) Type 3-Immune complex mediated Type 4-Delayed type hypersensitivy first 3 are immediate, last one is delayed. |
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type 1 |
IgE mediated (allergy) First exposure to allergen IL-4 drives B cels to produce IgE in repsonse to pollen antigens. antigen specific IgE binds to mast cells second exposure to pollen acute release of mast cell contents causes allergic reaction |
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mediators of Type 1 |
-Histamine - increase vascular permeability -heparin- increases vascular permeability -chemotactic factors- attract eosinophils + neutrophils -proteases- mucous secretion -leukotrienes and prostaglandins-similar to histamine |
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histamine can be released in two ways |
-Energy and ca2+ dependant degranulation reaction IgE fixation to mast cells + subsequent exposure to antigen Energy and Ca2+ independent release displacement induced by drugs such as morphine, mast cell damage due to venom or trauma |
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adverse effects of first generation H1 antihistmaines |
H1 receptor sedation CNS disturbances Appetite increase b-adrenergic receptor -hypotension dizziness tachycardia muscarinic receptor\ uriniary retention tachycardia serotonergic receptor appetite increase |
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atopic eczema /dermatitis |
Chronic inflammatory skin condition (itchy) which often develops in early childhood relapsing/remitting. has a genetic compotetn that leads to breakdown of skin barrier. condition tends to omprove throighout chidhoold. |
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treatment of eczema |
Avoid allergen antihistamines hyposensitization (injections of low doses of allergen) Acute stage: Fluid escapes from dilated dermal blood vessels to produce oedema Chronic stage: less oedema and vesiculation and more thickening of epidermis |
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treatment management in children |
Mild atopic eczema: Emollients, mild potency topical corticosteroids Moderate atopic eczema: Emollients, moderate potency tpical corticosteroids. topical calcineurin inhbitors bandages severe atopic eczema emollients poten topical corticosteorods topical calineurin inhibitors banages phototherapy systemic therapy. |
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Type 11 allergy |
Antibodies IGM or IGG bind to cell surgace antigens which can cause complement activation -lysis Epsonization -phagocytosis normal reaction but they are considered hypersensitive when the cause unwarrented tissue damage eg blood transfusions |
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type iii |
Antibodiy IGG attaches to soluble antigen leading to complex formation. complexes may deposit in blood vessel walls, joints, kidneys, skin. the reaction may take 3-10 hours after exposure to antigen known as arthus reaction. Can acuse oedema and tissue necrosis |
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type iv |
Th cells sensitized by an allergen develop into TH 1 leading to macrophage recruitment and activation. first contact sentitised a person subsequent contact elicits a reaction which is delayed for 1 or 2 days due to migration macrohphaes and t cells |
