The lungs are a pair of asymmetrical organs that facilitate gaseous exchange between the environment and the circulatory system. The lung on the right side of the chest has three lobes, and the lung on the left has two. The lungs are attached to the respiratory tract via primary bronchi that divide from the base of the trachea and enter their respective lung at the hilum. Each lobe is connected to a secondary or lobar bronchus that divides off from the primary bronchus. The secondary bronchi then further divides into tertiary or segmental bronchi that supply air to the different lobar segments through the bronchioles, alveolar ducts and terminate with clusters of alveoli. The bronchi are lined with goblet cells that secrete mucus. Mucus is a sticky substance that acts as a protective barrier against foreign material like dust and pathogens. The walls of the bronchi are also lined with …show more content…
Upon recognition of an antigen, the smooth muscle that lines the bronchi rapidly and irregularly contract in spasms, which restricts the airflow. The goblet cells lining the membrane swell and excrete excessive amounts of mucus. This causes the lining of the airways to thicken and reduce the diameter of the airways, further restricting the airflow. The walls also swell due to an influx of inflammatory secretions including eosinophils, neutrophils and lymphocytes from the blood vessels. These responses only allow partial exhalation of the air in the lungs, causing the lungs to become hyper inflated as inhalation is still occurring at the normal flow rate. Severe asthma attacks can result in total blockage of the bronchi, leading to hypoxia and then death if not re-opened. Atopic asthma can be induced by hypersensitivity to foreign particles such as dust mites. Alternatively, asthma may be non-atopic, caused by an upper respiratory tract