Question

bronchi are lined with glandular cells that produce secretions to catch inhaled particles. when bronchi are exposed to cigarette smoke or other airborne toxins, the glandular cells are replaced by squamous cells to handle the stress. which type of cellular alteration is this?
dysplasia
atrophy
hyperplasia
metaplasia

Explanation:

Metaplasia is the replacement of one differentiated cell type with another. In this case, glandular cells (original type) are replaced by squamous cells (new type) due to stress (exposure to cigarette smoke/airborne toxins), which fits the definition of metaplasia. Dysplasia involves abnormal cell growth and arrangement. Atrophy is a decrease in cell size/number. Hyperplasia is an increase in cell number.

Answer:

D. Metaplasia