Everything about Asthma totally explained
Asthma is a
chronic condition involving the
respiratory system in which the
airways occasionally constricts, becomes
inflamed, and is lined with excessive amounts of
mucus, often in response to one or more triggers. These episodes may be triggered by such things as exposure to an environmental stimulant such as an
allergen, environmental tobacco smoke, cold or warm air, perfume, pet dander, moist air,
exercise or exertion, or emotional
stress. In children, the most common triggers are viral illnesses such as those that cause the
common cold. This airway narrowing causes
symptoms such as
wheezing,
shortness of breath, chest tightness, and
coughing. The airway constriction responds to
bronchodilators. Between episodes, most patients feel well but can have mild symptoms and they may remain short of breath after exercise for longer periods of time than the unaffected individual. The symptoms of asthma, which can range from mild to life threatening, can usually be controlled with a combination of
drugs and environmental changes.
Public attention in the
developed world has recently focused on asthma because of its rapidly increasing
prevalence, affecting up to one in four urban children.
Signs and symptoms
In some individuals asthma is characterized by chronic respiratory impairment. In others it's an intermittent illness marked by episodic symptoms that may result from a number of triggering events, including upper respiratory infection, stress, airborne allergens, air pollutants (such as smoke or traffic fumes), or exercise. Some or all of the following symptoms may be present in those with asthma:
dyspnea, wheezing,
stridor, coughing, an inability for physical exertion. Some asthmatics who have severe shortness of breath and tightening of the lungs never wheeze or have stridor and their symptoms may be confused with a
COPD-type disease.
An acute exacerbation of asthma is commonly referred to as an
asthma attack. The clinical hallmarks of an attack are shortness of breath (
dyspnea) and either
wheezing or
stridor. Although the former is "often regarded as the
sine qua non of asthma",
Cause
Asthma is caused by a complex interaction of genetic and environmental factors that researchers don't fully understand yet. These factors can also influence how severe a person’s asthma is and how well they respond to medication. As with other complex diseases, many genetic and environmental factors have been suggested as causes of asthma, but not all of them have been replicated. In addition, as researchers detangle the complex causes of asthma, it's becoming more evident that certain environmental and genetic factors may only affect asthma when combined.
The
hygiene hypothesis is a theory about the cause of asthma and other allergic disease, and is supported by epidemiologic data for asthma. For example, asthma prevalence has been increasing in developed countries along with increased use of antibiotics, c-sections, and cleaning products. All of these things may negatively affect exposure to beneficial bacteria and other immune system modulators that are important during development, and thus may cause increased risk for asthma and allergy.
Environmental
Many environmental
risk factors have been associated with asthma, but a few stand out as well-replicated or that have a
meta-analysis of several studies to support their direct association:
