anaphylaxis

anaphylactic /an'euh feuh lak"tik/, adj.anaphylactically, adv.
/an'euh feuh lak"sis/, n. Pathol.
exaggerated allergic reaction to a foreign protein resulting from previous exposure to it.
[1905-10; ANA- + (PRO)PHYLAXIS]

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Severe, immediate, potentially fatal bodily reaction to contact with a substance (antigen) to which the individual has previously been exposed.

Often triggered by antiserum, antibiotics, or insect stings, the reaction's symptoms include skin flushing, bronchial swelling (with difficulty breathing), and loss of consciousness. Shock may follow. Milder cases may involve hives and severe headache. Treatment, consisting of injection of epinephrine, followed by antihistamines, cortisone, or similar drugs, must begin within minutes. Anaphylaxis may be caused by extremely small amounts of antigen.

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also called  anaphylactic shock 
 in immunology, a severe, immediate, potentially fatal systemic allergic reaction to contact with a foreign substance, or antigen, to which an individual has become sensitized.

      Anaphylaxis is a type I hypersensitivity reaction (immune system disorder). Asthma is another example of a type I reaction, but, whereas asthma is localized to the respiratory region of the body, anaphylaxis has effects throughout the organism. In all type I allergic reactions, sensitization occurs when a substance triggers the immune system to recognize it as a threat to the body. Upon subsequent exposure, an allergic reaction can occur. Almost any substance can induce anaphylaxis, but the most common agents are drugs such as penicillin, foods such as nuts and shellfish, and insect venom. Anaphylaxis may occur after contact with extremely small amounts of antigen and is more common in persons with a history of atopic dermatitis. In some cases anaphylaxis may be precipitated by exercise, and in other cases no cause is known.

      Symptoms of anaphylaxis include an itching of the scalp and tongue, difficulty in breathing because of swelling or spasm of the bronchi, skin flush of the whole body, an abrupt fall in blood pressure, vomiting or abdominal cramping, and unconsciousness. In milder cases hives may spread over the whole body, and often there is a severe headache. Treatment, which must begin within a few minutes of attack, involves the injection of epinephrine (epinephrine and norepinephrine) (adrenaline), followed by the administration of antihistamines, corticosteroids, bronchodilators, and fluids.

      The mechanism of anaphylaxis is mediated primarily by antibodies (antibody)—specifically those of the immunoglobulin E (IgE) class. These antibodies recognize the offending antigen and bind to it. The IgE antibodies also bind to specialized receptor molecules on mast cells (mast cell) and basophils (blood), causing these cells to release their stores of inflammatory chemicals such as histamine, serotonin, and leukotrienes, which have a number of effects, including constriction of the smooth muscles, which leads to breathing difficulty; dilation of blood vessels, causing skin flush and hives; and an increase in vascular permeability, resulting in swelling and a decrease in blood pressure.

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Universalium. 2010.

Look at other dictionaries:

  • anaphylaxis — n. 1. [Gr. ana back, way from + fy laxis security, protection.] 1. (Med.) hypersensitivity (to a protein or drug) resulting from prior contact with a substance. [WordNet 1.5] 2. (Med.) an immediate but transient allergic reaction to an antigenic… …   The Collaborative International Dictionary of English

  • anaphylaxis — anaphylaxis. См. анафилаксия. (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995 г.) …   Молекулярная биология и генетика. Толковый словарь.

  • anaphylaxis — (n.) see ANAPHYLACTIC (Cf. anaphylactic) …   Etymology dictionary

  • anaphylaxis — [an΄ə fə lak′sis] n. [ModL < Gr ana , intens. + phylaxis, a guarding < phylassein, to guard] a condition of hypersensitivity to proteins or other substances, requiring previous exposure to the allergenic substance and resulting in shock or… …   English World dictionary

  • Anaphylaxis — Infobox Disease Name = Anaphylaxis Caption = DiseasesDB = 29153 ICD10 = ICD10|T|78|2|t|66 ICD9 = ICDO = OMIM = MedlinePlus = eMedicineSubj = med eMedicineTopic = 128 MeshID = D000707 Anaphylaxis is an acute systemic (multi system) and severe Type …   Wikipedia

  • anaphylaxis — An induced systemic or generalized sensitivity; at times the term a. is used for anaphylactic shock. The term is commonly used to denote the immediate, transient kind of immunologic (allergic) reaction characterized by contraction of smooth …   Medical dictionary

  • anaphylaxis — anaphylactic shock anaphylactic shock n. (Med.) a severe form of physiological shock, often having a fatal outcome, caused by an extreme immunological reaction to antigens. It is a severe form of {anaphylaxis[2]}, and is characterized by smooth… …   The Collaborative International Dictionary of English

  • anaphylaxis — anafilaksija statusas T sritis ekologija ir aplinkotyra apibrėžtis Labai ūmi įjautrinto organizmo reakcija pakartotinai į jį patekus specifiniam alergenui. Dažniausia sukelia vabzdžių nuodai, kai kurie fermentai, vitaminai, antibiotikai.… …   Ekologijos terminų aiškinamasis žodynas

  • anaphylaxis — noun (plural anaphylaxes) Etymology: New Latin, from ana + prophylaxis Date: 1907 1. hypersensitivity (as to foreign proteins or drugs) resulting from sensitization following prior contact with the causative agent 2 …   New Collegiate Dictionary

  • anaphylaxis — n. [Gr. ana, again; phylax, guard] A state of excessive sensitivity to a serum or foreign protein that can result in a state of shock, that may develop with marked circulatory disturbances and possible death; anaphylactic adj …   Dictionary of invertebrate zoology

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