BIOLOGY Volume 1 - A Guide to General Biology - 2004

9. UTILIZATION OF ENERGY

9.7. Diseases of the Respiratory System

9.7.2. Bronchial Asthma

In asthma, breathing difficulties are caused by spasms of the smooth Muscle within the walls of the bronchioles. As these Muscles contract, the bronchiolar lumen narrows and may sometimes close completely. Exhalation is more impaired than inhalation because the pressure of the air leaving the Lungs compresses the tubes even further. During an asthmatic attack, breathing is accompanied by a characteristic wheezing or rattling sound, which is particularly pronounced during exhalation. Another distressing symptom is the excessive accumulation of thick mucus that is difficult to expectorate. It builds up in the bronchioles, further obstructing airflow. Bacteria can proliferate in this trapped mucus, leading to secondary Bronchitis. Additionally, breathing is hampered by Swelling of the bronchial mucosa.

At the ROOT of asthma is a hypersensitivity of the body to various substances—allergens—that are typically harmless to healthy individuals. The most common asthma triggers include pollen, house dust (which may contain microscopic mites or mold spores, for example), certain food components, or feather pillow fillings. An attack can also be triggered by emotional distress. Furthermore, asthmatic episodes may be brought on by chilling, physical exertion, or smoking. A matter of growing concern is the increasing prevalence of asthma among urban children, which is widely attributed to worsening air pollution from vehicle exhaust. Exhaust fumes contain specific substances capable of provoking asthma attacks, prompting stricter environmental legislation in industrialized nations in recent years. Nevertheless, asthma remains a complex condition, and further research is needed to determine who is most at risk and why. Anti-inflammatory medications can be quite beneficial in managing the disease.