<unk>  is transmitted via air droplets. It is caused by respiratory syncytial virus (RSV), which infects the nasopharyngeal mucosa. After the infection, the virus spreads to the lower airway tracts until it reaches the bronchioles, where viral replication takes place. The viral infection induces inflammation, which leads to edema and necrosis of the bronchiolar epithelium. Cough reflex occurs due to exposure of the subepithelial tissue and nerve fibers. Vascular permeability increases, leading to edema and swelling. Histopathologically,<unk>  obliterans shows intraluminal polyps, inflammatory infiltration, and macrophages. Constrictive<unk>  shows thickening of the airways and interluminal narrowing.
Bronchiolitis pathophysiology
Bronchitis pathophysiology
Pneumoconiosis pathophysiology
Emphysema pathophysiology
Acute bronchitis pathophysiology
Bronchitis risk factors
Hypersensitivity pneumonitis risk factors
Occupational lung disease risk factors