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Blood lec-20-by-dr-sadia


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Amna inayat medical college …

Amna inayat medical college
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  • 1. ALLERGIES IN THE “ALLERGIC” PERSON, WHO HAS EXCESS IGE ANTIBODIES • Some people have an “allergic” tendency. • Their allergies are called atopic allergies b/c they are caused by a nonordinary response of the immune system. • Allergic tendency is genetically passed from parent to child characterized by large quantities of IgE antibodies in the blood. • These antibodies are called reagins. • When an allergen enters the body, an allergen-reagin reaction takes place allergic reaction occurs.
  • 2. • IgE antibodies (the reagins) has a strong property to attach to mast cells and basophils. • Single mast cell or basophil can bind as many as half a million molecules of IgE antibodies. • When (an allergen) that has multiple binding sites binds with several IgE antibodies attached to a mast cell or basophils, immediate change in the memb of the mast cell or basophil.
  • 3. • Many of the mast cells and basophils rupturerelease special agents including • Histamine, • Protease, • Slow-reacting substance of anaphylaxis • (which is a mixture of toxic leukotrienes), • Eosinophil chemotactic subt, • Neutrophil chemotactic subt , • Heparin,& platelet activating factors
  • 4. • These substance cause such effects: • Dilation of the local blood vessels; • Attraction of eosinophils and neutrophils to the reactive site; • Increased permeability of the capillaries • Contraction of local smooth muscle cell.
  • 5. ANAPHYLAXIS. • When a specific allergen is injected directly into the circulation,  react with basophils & mast cells • Widespread allergic reaction occurs throughout the vascular syst & closely associated tissues. This is called anaphylaxis. • Histamine is released into the circulation causes • body-wide vasodilation • increased permeability of the capillaries with resultant marked loss of plasma from the circulation.
  • 6. • An occasion person dies of circulatory shock within a few min unless treated with epinephrine to oppose the effects of the histamine. • From the activated basophils and mast cells is a mixture of leukotrienes called slow-reacting subt of anaphylaxis. • Leukotrienes can cause spasm of the smooth muscle of the bronchioles, eliciting an asthma-like attack, causing death by suffocation.
  • 7. URTICARIA. • Antigen entering specific skin areas and causing localized anaphylactoid reactions. • Histamine released locally causes • (1) vasodilation that induces an immediate red flare • (2)increased local permeability of the capillaries  leads to local circumscribed areas of swelling of the skin. • Swellings are commonly called hives. • Administration of antihistamine drugs to a person before exposure will prevent the hives.
  • 8. HAY FEVER • Allergen-reagin reaction occurs in the nose. • Histamine released  causes local intranasal vascular dilation increased capillary pressure & increased capillary permeability. • Cause rapid fluid leakage into the nasal cavities and deeper tissues of the nose nasal linings become swollen and secretory (allergic rhinitis). • Antihistamine drugs can prevent this swelling reaction. • Other products of the allergen reagin reaction cause irritation of the nose sneezing syndrome.
  • 9. ASTHMA. • Asthma often occurs in the “allergic” type of person allergen- reagin reaction occurs in the bronchioles of the lungs product released from the mast cells is slow-reacting substance of anaphylaxis,  causes spasm of the bronchiolar smooth muscle. • Person has difficulty in breathing until the reactive products of the allergic reaction have been removed. • Administration of antihistaminics has less effect on the course of asthma because histamine does not appear to be the major factor eliciting the asthmatic reaction.
  • 10. LEUKOTRIENES • 20 Carbon containing fatty acids derivatives of A,B,C,D and E types. • Produce tremendous of smooth muscles of pulmonary airways leading to bronchospasm . • Leukotrienes C4, D4, E4 represent the slow reacting substance of anaphylaxis.