Chronic bronchitis causes which change in the bronchiolar epithelium?

Chronic bronchitis causes which change in the bronchiolar epithelium?

• A. Hyperplasia
• B. Metaplasia
• C. Necrosis
• D. Atrophy

Answer: (B)

Chronic irritation of the airways prompts metaplastic change in the bronchiolar epithelium. Metaplasia is when one mature cell type is replaced by another better able to withstand ongoing stress. In the bronchi, the normal lining is pseudostratified ciliated columnar epithelium that helps clear mucus. With chronic bronchitis, this epithelium can transform into stratified squamous epithelium. While this squamous type is more resistant to constant irritation, it lacks cilia and goblet cells, so mucociliary clearance is impaired and the area becomes more prone to mucus plugging and infection. This contrasts with hyperplasia (increase in cell number of the same type), necrosis (cell death), or atrophy (loss of cells or size); none of those describe the tissue remodeling occurring in this context.

Chronic irritation of the airways prompts metaplastic change in the bronchiolar epithelium. Metaplasia is when one mature cell type is replaced by another better able to withstand ongoing stress. In the bronchi, the normal lining is pseudostratified ciliated columnar epithelium that helps clear mucus. With chronic bronchitis, this epithelium can transform into stratified squamous epithelium. While this squamous type is more resistant to constant irritation, it lacks cilia and goblet cells, so mucociliary clearance is impaired and the area becomes more prone to mucus plugging and infection. This contrasts with hyperplasia (increase in cell number of the same type), necrosis (cell death), or atrophy (loss of cells or size); none of those describe the tissue remodeling occurring in this context.