The mechanisms that cause asthma are complex and vary among population groups and even between individuals. Genetic susceptibility, probably contains several genes, together with various environmental components are the main causes of asthma. Many people with asthma also have allergies and researchers are investigating the factors in allergic responses that can cause asthma in some people. Not all people with allergies have asthma, and not all cases of asthma may be explained by an allergic response. Some experts are looking for a connection between viral infections and the development of asthma in genetically susceptible people. Investigators are also detected in some patients with asthma, overproduction of an enzyme called highly potent endothelin, which is responsible for the reduction of blood vessels and airways hyperresponsiveness of airway mucus secretion and perhaps even can trigger inflammatory agents. In addition to respiratory problems, researchers are also finding that abnormalities in the tissue of the lung itself can contribute to asthma. Gastroesophageal reflux disease also contributes to some cases of asthma.
Allergic response
In people who have asthma caused by an allergic response, a series of events not yet fully implications, leading to inflammation and hyperreactivity in the airways. The factors in this orchestra inmunitrio system factors seem to be the white blood cells called-TH2, a subgroup called helper T cells. These cells overproduce interleukins (IL, by acronym in English), a subset of immune factors known as cytokine. Of particular interest are IL 9 and the IL 5. Interleukin 5, for example, seems to attract eosinophils are important for airway hyperreactivity. Interleukin-9 stimulates the release of antibody known as immunoglobulin E (IgE). During an allergic attack, these antibodies can bind to various cells in the immune system, including eosinophils, basophils and mast cells, which are generally concentrated in the lungs, skin and mucous membranes. Once IgE binds to mast cells, these cells are programmed to deliver various chemicals, particularly those known as leukotrienes, which cause inflammatory changes in the airways of the lungs, including the reduction of airway production mucus and stimulation of nerve endings in the lining of the airway.Genetic Factors
Genetic factors play a role in the disease, about a third of all people with asthma share the problem with a close family member. A recent major study, researchers found that specific genetic regions increase the risk of asthma in different ethnic populations, such as African Americans, Hispanics and Caucasians. Interestingly, the genetic regions associated with allergies and hyper - widely factors associated with asthma - were not as significant as others.
Environmental factors that precipitate an asthma attack
Allergens and other common triggers
Allergens are most often the trigger of asthma in children. In a study of asthmatic children in the inner cities, about 37% were allergic to cockroaches, 25% of dust mites and 23% of cats. Cat allergies can trigger severe asthma in one study tripled the risk of hospitalization. In the same study, it was found that roach allergies doubled the risk; allergies to dust mites, found in house dust, and the dogs seemed to have no effect on hospitalization, although capable of triggering the attacks asthma. An asthma attack can also be caused by cold air, thunder storms, exercise, extreme emotions direct emotional and lung irritants such as pet dander, smoke snuff, pollen, molds and fungi.
Environmental Contaminants
Environmental pollution has been associated with the development of asthma. Specific pollutants projected for its role in triggering asthma include ozone, diesel fumes, sulfur dioxide produced by the paper industry and energy and nitrogen dioxide emitted from exhaust pipes and gas furnaces. Children seem to be particularly susceptible to soot and other small particles in the air.
Secondhand Smoke
Studies are finding that secondhand smoke in the home increases the risk of amsa in children. This risk extends even to the fetus of pregnant women who smoke.
Exercise
The running or extreme exercise can precipitate an attack by 80% of children with asthma. The exercise-induced asthma (EIA acronym) is different from ordinary allergic asthma, some people have only one type of asthma, some have both. EIA occurs most often during intense exercise in cold dry air.
Food Allergies
About 8% to 10% of children with asthma also have food allergies. Asthmatic children with food allergies also seem to have a high risk of potentially fatal reactions to such foods. In infants and young children, it seems that allergy to eggs is a major predictor of asthma. If young children show signs of, or are positive to examine food allergies, parents should use caution to prevent additional exposure to any common factor that triggers asthma.
Low birth weight
It seems that the people who started their lives with low birth weight are at risk of suffering from asthma, bronchitis and other lung disease throughout their lives. Experts suggest that the airways develop abnormally in malnourished fetuses.
Immunizations
One theory to explain the marked increase in childhood asthma, because the higher rate of childhood immunizations to certain infectious diseases, including measles and whooping cough. Without vaccination, In-law children contract these infections, immune system white blood cells called helper download T-1 (TH1, by acronym in English), cells that stimulate other immune factors that fight infection. At the same time, suppresses the fighter TH1 T cell infection by alternate called T-2 (TH2, by acronym), these white blood cells commonly trigger antibodies that attack the airborne allergens and cause the inflammatory response typical asthma. Experts postulate that in some children who are vaccinated against these diseases, TH2 cells remain active and stimulate asthma.
Medical disorders taxpayers
Much as 89% of patients with asthma also have gastroesophageal reflux disease (GERD, for acronym), the cause of heartburn. GERD may trigger asthma in many cases through spillage of the acid in the resulting airway hyperreactive triggers a response. GERD may be suspected in patients who do not respond to treatments for asthma, whose asthma attacks are episodes of heartburn, or whose seizures are worse after eating or exercise. In such cases, treatment of heartburn can solve asthma [see Well-Connected Report # 85 Heartburn and Gastroesophageal Reflux Disease]. Sinusitis and rhinitis (inflammation of the sinuses and nasal cavity) and polyps in the nose may contribute to the symptoms of asthma.
