What is asthma?
Asthma is a chronic inflammatory respiratory disease characterized by periodic attacks of wheezing, shortness of breath, and a tight feeling in the chest. A cough producing sticky mucus is symptomatic. The symptoms often appear to be caused by the body's reaction to a trigger such as an allergen (commonly pollen, house dust, animal dander: see allergy), certain drugs, an irritant (such as cigarette smoke or workplace chemicals), exercise, or emotional stress. These triggers can
cause the asthmatic's lungs to release chemicals that create inflammation of the bronchial lining, constriction, and bronchial spasms. If the effect on the bronchi becomes severe enough to impede exhalation, carbon dioxide can build up in the lungs and lead to unconsciousness and death. Following a steady 30-year decline, asthma deaths in the United States, especially among poor, inner-city blacks and among the elderly, began to rise from the late 1970s through the early 1990s. There is no cure for asthma. Although the disease may go through a period of quiescence, it appears that childhood asthmatics do not outgrow the disease as previously believed. Treatment includes inhaled or oral steroids or bronchodilators (albuterol, theophylline), breathing exercises, and, if possible, the identification and avoidance of triggers.
Asthma is an immunological disease which causes difficulty in breathing. It is a form of type I hypersensitivity in which the bronchioles in the lungs are narrowed by inflammation and spasm of the lining of the airway wall. A person with asthma may experience wheezing, shortness of breath and poor exercise tolerance. Inflmmation occurs when irritated tissues swell and produce extra mucus, creating a condition known as bronchoconstriction. The combination of the two can cause constriction of complete blockage of the airways and can initiate symptoms of an asthma attack. Symptoms of an asthma attack can include wheezing, coughing, chest tightness and shortness of breath. Asthma attacks may occur at anytime, but there are risk factors that can trigger an attack.
Asthma is a disease that affects the breathing passages, or airways, of the lungs. Asthma is a chronic (ongoing, long-term) inflammatory disease that causes difficulty breathing. During normal breathing, air is taken in through the nose and mouth. It goes down your windpipe, through your airways, and into the air sacs. When you breathe out, air is expelled from the lungs in the reverse order. During an asthma attack, the muscles around the airways tighten, making the opening in the airways smaller. The lining of the airways swells from inflammation, which causes an increase in mucus that blocks the airways. Because it's more difficult to breathe out than to breathe in, more air is retained in the air sacs in your lungs with each breath. Someone having an asthma attack may feel as though he or she is breathing through a narrow straw or, in the case of a severe attack, may even have the feeling of near suffocation.
The changes that take place in the lungs of asthmatic persons makes the airways (the "breathing tubes," or bronchi and the smaller bronchioles) hyper-reactive to many different types of stimuli that don't affect healthy lungs. In an asthma attack, the muscle tissue in the walls of bronchi go into spasm, and the cells lining the airways swell and secrete mucus into the air spaces. Both these actions cause the bronchi to become narrowed (bronchoconstriction). As a result, an asthmatic person has to make a much greater effort to breathe in air and to expel it. Cells in the bronchial walls, called mast cells, release certain substances that cause the bronchial muscle to contract and stimulate mucus formation. These substances, which include histamine and a group of chemicals called leukotrienes, also bring white blood cells into the area, which is a key part of the inflammatory response. Many patients with asthma are prone to react to such "foreign" substances as pollen, house dust mites, or animal dander; these are called allergens. On the other hand, asthma affects many patients who are not "allergic" in this way. When an exacerbation or "attack" of asthma takes place, the inflammation in the airways causes the lining of the breathing passages to swell. This swelling narrows the diameter of the airway, eventually to a point where it is hard to exchange enough air to breathe comfortably. This is when coughing, wheezing, and the sensation of distress start.
Medically, asthma is a name assigned to a group of symptoms that typically include shortness of breath, wheezing, coughing, and chest tightness. Symptoms can occur in various combinations (one, several, or all) and may range from mild to severe. Symptoms are usually intermittent, perhaps happening only on rare occasions but may occur seasonally or monthly, weekly, or even daily. In the most severe cases, symptoms are present continuously. Asthmatic symptoms are usually quite variable; someone with asthma may go for periods of time without symptoms, and then suddenly have severe episodes for days at a time. The most common symptom recognized by both physicians and patients is wheezing. Wheezing is a whistling or rumbling sound that comes from the chest expiration. It may be very loud or barely audible. With mild asthma, symptoms occur no more than twice a week (with nighttime attacks no more than twice a month). The attacks don’t last long, and they are alleviated quickly with medication. There are no symptoms between attacks. With moderate asthma, symptoms occur almost every day and require an inhaler almost every time an attack occurs for symptom relief. With severe asthma, symptoms are present most of the day every day. They restrict activity, and they have often necessitated a hospital stay.
Asthma usually begins in childhood or adolescence, but it also may first appear during adult years. While the symptoms may be similar, certain important aspects of asthma are different in children and adults. Children born to families with a history of allergies or asthma are more likely to have asthma. Children who live in urban areas, where there is a higher incidence of air pollution, or live in a home that has high levels of dust mites or cigarette smoke, are also at a higher risk for asthma. Infants born prematurely or who suffer lung damage shortly after birth are also more likely to have asthma. |
