The primary physiological alteration in the development of asthma is:
A. Bronchial inflammation and dyspnea
B. Hypersecretion of abnormally viscous mucus
C. Infectious processes causing mucosal edema
D. Spasm of bronchial smooth muscle
Correct Answer: D. Spasm of bronchial smooth muscle
Asthma is the presence of bronchial spasms. This spasm can be brought on by allergies or anxiety. Asthma is a condition of acute, fully reversible airway inflammation, often following exposure to an environmental trigger. The pathological process begins with the inhalation of an irritant (e.g., cold air) or an allergen (e.g., pollen), which then, due to bronchial hypersensitivity, leads to airway inflammation and an increase in mucus production.
Option A: The primary physiological alteration is not inflammation. Airway obstruction occurs due to the combination of inflammatory cell infiltration; mucus hypersecretion with mucus plug formation; and smooth muscle contraction.
Option B: There is the production of abnormally viscous mucus, not a primary alteration. If not corrected rapidly, asthma may become more difficult to treat, as the mucus production prevents the inhaled medication from reaching the mucosa. The inflammation also becomes more edematous. This process is resolved (in theory complete resolution is required in asthma, but in practice, this is not checked or tested) with beta-2 agonists (e.g., salbutamol, salmeterol, albuterol) and can be aided by muscarinic receptor antagonists (e.g., ipratropium bromide), which act to reduce the inflammation and relax the bronchial musculature, as well as reducing mucus production
Option C: The infection is not primary to asthma. These irreversible changes may become irreversible over time due to basement membrane thickening, collagen deposition, and epithelial desquamation, and airway remodeling occurs in chronic disease with smooth muscle hypertrophy and hyperplasia.