Anatomy & Histology · single question
Metaplasia of tissue in COPD results in which type of epithelium?
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Correct answer: A. Stratified squamous keratinized epithelium
The normal respiratory epithelium is pseudostratified ciliated columnar epithelium with goblet cells. In COPD (from chronic cigarette smoking irritation), this undergoes squamous METAPLASIA — the normal respiratory epithelium is replaced by stratified squamous KERATINIZED epithelium. This is a protective adaptation to chronic irritation (similar to how skin forms calluses) but compromises mucociliary clearance.
- A. CORRECT. In COPD/chronic smoking, the normal pseudostratified ciliated columnar epithelium of the bronchi undergoes metaplasia to stratified squamous KERATINIZED epithelium — a response to chronic chemical irritation from tobacco smoke.
- B. INCORRECT. Stratified columnar epithelium is rare in the body — not the result of COPD metaplasia.
- C. INCORRECT. Stratified non-keratinized squamous epithelium is found in the oral mucosa and esophagus — not the result of COPD-related metaplasia.
- D. INCORRECT. Pseudostratified squamous epithelium is not a recognized tissue type. The NORMAL respiratory epithelium is pseudostratified CILIATED COLUMNAR — and this is what gets replaced by metaplasia.
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