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Frequent questions | |
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He asks the doctor | |
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Beginning | |
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WHAT IS THE ALLERGY? | |
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 DEFINITION INFORMATION REACTION ALLERGENS ATOPIA TO BE ABLE TO CONSULT MORE |
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The allergy is an exaggerated answer of our organism when it contacts certain substances originated from the exterior. The substances capable of provoking an allergic reaction are known as substances alergénicas or, simply, alérgenos. It is in the immune system, or defensive system of the human organism, in which the allergy is framed. The above mentioned system is constituted by a set of cells that we find circulating so much along the blood like being part of different organs. His mission is fundamental: to recognize the entry in our body of strange elements and to organize the defense opposite to them. This is known as an immune answer. Thanks to her our immune system recognizes the bacteria or virus, reagents foreign to our organism, like causers of the infection. If it was not like that, any infection of those that we suffer along our life (a flu or a cold) might have fatal consequences on not having found resistance to his progression. Apparently the immune answer is of big importance although, sometimes, it is a cause of serious problems:
The possible alérgenos are very numerous and they can get in touch with us across diverse means:
We all are exposed to many of these substances and, nevertheless, most of us we live together with them without problems: we can eat peanuts and eggs, can be treated by penicillin if we need it... The immune reaction that our organism produces opposite to these substances is of low intensity and we do not perceive it. On the contrary, the person allergic to a substance will unleash an exaggerated answer whenever between in contact with her. So that this allergic reaction takes place there are enough negligible quantities of the alérgeno. Finally, the cause of an allergy must not assume to a substance in particular, but to the individual, who is genetically predisposed to develop an answer exaggerated after the contact repeated with the matters potentially capable of inducing to a defensive reaction in the organism. More than 15 % of the population is allergic to some substance. Fortunately most of the allergic reactions have scarce importance and do not cause big inconveniences. Nevertheless, sometimes they can be extraordinarily serious and be necessary urgent medical intervention. Since the immune system is distributed extensively in our organism, it is no wonder that the allergic reactions are capable of unleashing very diverse disorders, according to the place where the reaction takes place:
The man can present diverse classes of immune reactions, but here we are going to consider only one of them (implied, for example, in the asthma appearance). The called allergic reaction is a type I. The cells that compose the immune system (the macrophages and the lymphocytes T and B), on having contacted a strange substance to the organism, (alérgeno or antigen) initiate a series of reactions that reach with the formation of a few molecules called antibodies (Ig) or antibodies that join the alérgeno and, for diverse mechanisms, they obtain his destruction and elimination. These antibodies can be of 5 different types: IgG, IgA, IgM, IgD, and IgE. The IgE and, less often, the IgG type 4 are the involved ones in the allergic reaction type I, characteristic of the asthma and of most of allergic processes. The persons allergic to a substance (alérgeno) present in the surface of the mastocitos (a few cells of the blood) multiple molecules of Ig capable E of recognizing the presence of the above mentioned substance. This IgE formed in previous contacts with the allergen that provoked the sensitization opposite to the same one. Namely the cells formed with memory (lymphocytes B memory) that, on having contacted again the above mentioned allergen, will arrange the production of big quantities of specific IgE against that alérgeno. After the IgE union is carried out with the allergen (as if of a key and his lock it was talking each other) the liberation will be provoked on the part of the mastocito of a big number of substances (histamine, serotonina, bradiquinina...) known like mediators of the allergy since they are those who will determine the declarations of the allergic reaction in the different organs. In the lung they produce the inflammation of the mucous membrane of the bronchial wall and the contraction of the muscular fibres, giving place to the asthmatic crisis. So that all this happens it is necessary that the alérgeno that enters the bronchial tree finds a part of the IgE directed against him (specific IgE). Namely every allergen only fits in his IgE and this one only is in enough number in the persons allergic to the above mentioned allergen. If a person is allergic to the olive tree pollen it will have in his blood and in the surface of his mastocitos molecules of IgE anti-pollen of olive tree that they are not in sufficient quantity in the rest of the population who is not allergic to the same one. It is known that every mastocito can go so far as to have approximately 80.000 IgE molecules connected in his surface. As the mastocitos are distributed extensively by the organism we can imagine the big quantity of molecules of IgE that an allergic individual goes so far as to have when it is sensitive.
The persons whose immune system, on having contacted environmental substances, reacts producing an enormous IgE quantity turn in allergic and are named persons atópicas. It is a characteristic determined genetically, that is to say inherited that, usually, affects diverse members of the same family. This predisposition to the allergy is evident normally opposite to diverse alérgenos, being much rarer the cases of allergy only to only one substance. |
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DEFINITION |
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