ASTHMA HELPLINE

Asthma is a clinical syndrome characterized by :

• Episodic reversible airway obstruction,
• Increased bronchial reactivity, and
• Airway inflammation.

Asthma is now recognized to result from complex interactions among inflammatory cells, their mediators, airway epithelium and smooth muscle, and the nervous system.

In susceptible individuals, these interactions can lead to following symptoms:

• Breathlessness,
• Wheezing,
• Cough, and
• Chest tightness.

Risk factors for asthma include a family history of allergic disease, the presence of allergen-specific immunoglobulin E (IgE), aeroallergen exposure, viral respiratory illnesses, and a lower socioeconomic status.

Lungs allow oxygen to enter the body in exchange for its waste product, carbon dioxide. As the oxygen passes through the nose and mouth, it is rapidly warmed and moistened to avoid injury to the delicate lining of the airways.

The nose and airways also trap large particles (dust, pollen, molds, bacteria) and chemicals (smoke, sprays, odors), which could cause serious injury to the lungs.

The air is then transported through smaller airways. These airways branch like a tree, so that millions of small airways can carry oxygen to the tiny air sacs called alveoli.

The airways have a delicate cellular lining (mucosa), which is coated with a thin layer of mucus, as is present in the nose. Foreign particles are trapped by the sticky mucus and eventually removed from the airways through the normal cleansing process.

The process is assisted by the movement of tiny "whip-like" structures called cilia which move the mucus and trapped foreign particles up toward the mouth and nose where they are coughed and sneezed out or swallowed.

Bundles of muscles surround the airways, and the contraction of these muscles allows airways to selectively direct the flow of air.