Asthma is by no means a new medical condition. Over two thousand years ago, it was already well known to the ancient Greeks who gave it its present name, which aptly means "to breathe hard." In the simplest terms, Asthma is a breathing disorder, but in order to understand what happens during a typical asthma attack, you need to know some basics about the process of breathing and the anatomy of the respiratory system.
Under normal circumstances, when you breathe, air is drawn in through your mouth and nose and enters the chest through a large tube known as the trachea, or windpipe. At its base the windpipe divides into two slightly smaller, muscular breathing tubes known as the bronchi (singular: bronchus). The bronchus that leads to the right lung is called the right bronchus, and the one to the left lung is the left bronchus. Each bronchus further divides and subdivides within the lungs to form hundreds of microscopic breathing tubes called bronchioles, and thousands of air sacs, called alveoli. It is through the thin walls of these air sacs that inhaled oxygen is transferred to the blood and carbon dioxide and other waste gases are discharged from the body when exhaled through your nose and mouth.
The healthy respiratory system possesses several efficient means of ridding itself of potential airborne troublemakers. Of these, mucus and cilia are perhaps the two most important cleansing and eliminating mechanisms. Mucus, secreted by special cells called goblet cells that line the breathing tubes, serves as the chief cleaning and lubricating fluid of the respiratory system. Cilia, which are the many thousands of tiny, beating hairlike fibers that line the tubes, continually drive mucus and other debris upward toward the mouth and nose where they may be easily eliminated.
Asthma attacks can be thought of as a disruption in the delicate workings of the breathing system, and these attacks involve three events: spasm, swelling, and excessive mucus production. Bronchospasm occurs early in an attack. This is a response to inhaled germs, irritants, or allergens in which the muscle fibers making up the walls of the bronchi contract involuntarily and forcefully. It is believed to result from dysfunction of the autonomic nervous system, that branch of your nervous system over which you have no conscious control. Airway hyperreactivity, a term often used by doctors, is another name for bronchospasm.
At about the same time in the an asthma attack, the mucus-producing cells lining the breathing tubes begin producing large amounts of thick, sticky, irritating mucus, or phlegm. Phlegm is largely responsible for triggering the coughing so characteristic of asthma.
If an attack is not checked, the walls of the bronchi soon swell from inflammation, resulting in additional narrowing or obstruction of the airways. When this occurs, excessive amounts of air eventually become trapped in the lungs, and the chest cavity swells. Attempting to exhale this increased volume of air forcibly through the markedly narrowed breathing tubes results in the wheezing characteristic of asthma. Without prompt treatment, some breathing tubes plug with mucus and others close off entirely, causing shortness of breath, a feeling of gasping for air, and speechlessness. Prompt intervention generally restores breathing to normal, and for that reason asthma is defined as an "intermittent, reversible, obstructive airway disease."
