The respiratory system processes oxygen using the lungs and airways, with the smallest functional unit being alveoli. The main functions of the respiratory system are air conduction, air filtration, and gas exchange (Ross 664). These functions are sometimes disrupted by disorders of the respiratory system, one of which is asthma.
Asthma is characterized by chronic coughing, wheezing, tightness of the chest, and shortness of breath, but some people may not experience these symptoms. Asthma is diagnosed with a physical exam, a lung function test called spirometry, chest x-rays, an allergy test, and a bronchoprovocation test to measure sensitivity to various common triggers (“What is Asthma?”). Internally, people with asthma experience a trigger which causes inflamed, swollen airways, which can lead to an asthma attack (“Learning More About Asthma”). Common triggers include cold air, allergens, irritants, sulfites, medications, respiratory infections, and physical activity (What is Asthma?”).
The etiology of asthma is not fully known, but the main factors that appear to play a role in the development of asthma are genetics, allergies, respiratory infections, and environment. If a child’s parents have asthma, the child is also likely to develop asthma. Certain allergies are associated with asthma (“Learning More About Asthma”). The risk of developing asthma increases if the child grows up in an environment where there are particles, like cigarette smoke, in the air. Another risk factor is if the child catches respiratory infections while the immune system and lungs are not fully developed. Parasites, such as Dermatophagoides pteronyssinus, or the house dust mite, can also induce asthma. When the feces of the mite are inhaled, the peptidases in the fecal matter break down the zona occuludens junctions in the epithelium of the lung, making the lung tissue vulnerable to antigens, initiating a strong immune response that results in an asthma attack (Ross 128).
Eosinophils are abundant in the airway walls of people suffering from asthma because of the chronic inflammation (Ross 282). Smaller airways have the eosinophils in the outer portion of the airway, between the smooth muscle and alveoli, while larger airways have the concentration of eosinophils in the inner portion of the airway, between the smooth muscle and basement membrane. In severe asthma cases, elevated levels of neutrophils have also been observed, particularly in patients that died from asthma (Saetta).
Clara cells are cells that secrete proteins and lack cilia. They are found in the bronchioles of the lung. The function of Clara cells is to protect the epithelium of the bronchioles by secreting various proteins and detoxifying inhaled substances (“Clara Cell”). One of the secretions of Clara cells is called Clara cell secretory protein 16, abbreviated as CC16. People with asthma have higher levels of CC16 protein in their serum, and have lower levels of CC16 in their...