The term 'asthma' has been derived from an old Greek word which means 'to pant'. It is basically a chronic condition which affects the air passages when they are stimulated by environmental factors or allergens that act as triggers. There are two particular ways in which the air passage respond to asthmatic triggers: 1) hyperresponsiveness and 2) inflammation. When these responses occur, it results in the typical symptoms such as coughing, wheezing, and dyspnea, or labored respiration.
Hyperresponsiveness: In this condition when allergens or any other irritants are inhaled, it results in constriction of the smooth muscles. Constriction of the air passages in response to an allergen is a normal reaction that occurs in everybody; however, in asthma patients, it results in a special kind of hyperreactive response.
In people who do not have asthma, when an irritant is inhaled, the air passages relax as well as open out in order to expel the irritant from the lungs. However, in those who have asthma, there is no relaxation of the air passages, and instead they become narrow, leading to panting or breathlessness. It is thought that there may be a defect in the smooth muscles of those who are afflicted with this respiratory disorder.
Inflammation: Inflammation follows the hyperresponsive stage. When the air passages are subject to allergens or any other environmental triggering factors, the immune system kicks in, delivering immune factors like white blood cells to the area. These cause the air passages to become swollen, fill up with fluid, and produce a sticky, thick mucus. These combine to cause breathlessness, wheezing, the inability to inhale or exhale adequately, and a cough that produces phlegm.
This inflammatory response affects everybody afflicted with asthma, even mild cases.
What Exactly Causes Asthma?
While what exactly causes asthma is still not fully understood, research has shown that it can be triggered by many factors such as genetics, childhood development, improper development of the immune system and the lungs, environmental factors, and various types of infections.
Asthma and Genetics
Scientists and doctors accept the fact that asthma is a hereditary disease. But, they have not yet identified the gene, or genes, that are involved in this condition. It is thought that the genes that are associated with asthma are linked to the immune system and the lungs. It is widely known that 'atopic diseases', like asthma, allergic rhinitis, and dermatitis, occur in some form or the other in families.
Asthma and the Immune System
Research has revealed that the immune system of adults and children who have respiratory problems responds quite differently compared to others. People who have asthma are generally allergic, and have allergic reactions to factors that cause no problems to others. The immune system of allergic people overreacts when exposed to ordinary substances like cat dander, mold, and pollen. Sometimes, the immune system could even overreact to bacteria and virus, increasing the chances of an asthma attack.
Asthma and Childhood
The initial months as well as years in the life of a child is a vital period during which he/she could become predisposed to developing this condition. This is due to the abnormalities in the development as well as growth of the lungs. Premature babies are particularly vulnerable to respiratory diseases and infections, since their lungs are not completely developed when they are born. Sometimes, an infection could lead to inflammation, thereby injuring the tissues of the lungs.
Asthma and the Environment
There are several non-immunologic or non-allergic factors in the environment that can trigger the onset of asthma. When a person susceptible to asthma is exposed to these irritants, there are higher chances of them developing full-blown asthma. Some of them are secondhand smoke for an extended period of time, air pollution, paints, and indoor chemicals.
Research is still being conducted to understand better how the above factors affect the development of allergies like asthma.