LReynolds
Many of us have experienced an allergic reaction. We may have gotten the sneezes in the spring or fall or suffered from poison ivy rash. We may be allergic to certain medications, like penicillin, or to insect stings. All of these reactions are the result of mechanisms in our bodies that may be inherited from our parents or may have developed as the result of repeated exposure or a combination of factors unique to our experience. Allergies can appear and recede at any time during our lives, further challenging our ability to predict what will trigger an allergic reaction.
Allergic reactions are actually defense mechanisms. Why they work one way in certain people and not in others is a medical mystery that involves genetic predisposition, environmental factors and certain behaviors on the part of the person who has the allergy. The mechanism that sets off the reaction is the same in each case. Some toxin or irritant acts as the allergen. It might be pollen, mold, oils, venom, skin dander or some other organic source. It may seem simple, like pollen, or complex, like groups of foods, but it generally boils down to one compound present in the source or each item in a group. White blood cells, the cells that act as defenders of the body, sense a threat and signal the rest of the body's defenses by creating antibodies to attack the invading organism, in this case, the allergen. Antibodies create a number of reactions, depending on the source and type of invasion that is happening. The reactions to infections by bacteria and viruses are similar to those against allergens.
The white blood cells act like the generals, sending troops, or mediators and hormones out to do battle with the invaders. When the invader is an allergen, the mediators sent are histamines. These chemicals stimulate the development of more white cells and together, they rush to the location of the invasion by the allergens. Histamines and white blood cells battle the allergens by irritating or inflaming the area until the allergen is expelled. The offending allergens are repelled using expectoration (sneezing and coughing for allergens inhaled or eaten) or elimination (rashes that kill with heat and flush allergens away). Sensitivity and degree of exposure to an allergen determines the severity of the reaction but repeated exposure to an allergen without benefit of a substance that controls the production of histamines, called an "antihistamine," may increase the severity of reactive symptoms. Certain medical conditions, such as asthma, lung disease and respiratory conditions, can also aggravate symptoms.
Source: KING.NET
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