USMLE Step 1 Question 360

Question:

A 60 year old woman comes to your office for her follow-up visit after being hospitalized for an acute COPD exacerbation. She has a 30 pack year smoking history and complains of a chronic, productive cough. She is able to walk 50 feet before getting short of breath. On physical exam, there are decreased breath sounds bilaterally and crackles heard at both bases. It has been shown that cigarette smoking leads to goblet cell metaplasia and can contribute to the chronic bronchitis experienced by COPD patients. What level of the respiratory tract does not contain goblet cells?

Correct Answer: E.  Terminal bronchioles

The respiratory tract consists of many different types of cells. Pneumocytes, both type I and type II, are located in the alveoli. There is, however, different histology higher up in the respiratory tree.

Goblet cells exist in the bronchi and bronchioles (choices B and C), but do not extend into the terminal bronchioles (choice E).

Goblet cells secrete mucus to trap foreign objects that will eventually be carried out of the lungs by the mucociliary system.

Pseudocolumnar ciliated epithelial cells extend further, to the respiratory bronchioles. These cells move mucus secretions out of the lungs towards the mouth. (CONSIDER: As per high yield histology by Ronald Dudek, simple ciliated columnar epithelium starts at the level of Bronchioles. This transforms into simple ciliated cuboidal epithelium inside terminal and respiratory bronchioles) Note: I think this question has more than one answer: goblet cells are not found in the alveolar ducts either.

Note 2: In that case they shouldn’t be present in respiratory bronchioles either, apart from alveolar ducts. A, D, and E should all be correct.

Note 3: As per First Aid 2010, “goblet cells extend only to the terminal bronchioles” so only A and D are correct.