A 50-year old man has a 30 year history of smoking. For approximately 6 months per year for the preceding 5 years, he has had copious sputum production. This sputum production is most likely closely related to increased numbers of which of the following cell types in his bronchioles and small (less than 3 mm) bronchi?
The patient has chronic bronchitis, which has been clinically defined to be chronic cough with copious sputum production that has been present for at least 3 months in 2 consecutive years. Smoking and inhalation of other irritating substances (including smog) are usually associated. While the sputum production of early chronic bronchitis is the result of hyperophy of submucosal glands in larger bronchi, in late and more severe cases, goblet cell metaplasia of bronchioles and small bronchi also contributes significantly to the mucus production. Other microscopic changes that occur include increased infiltration of small airways by alveolar macrophages and fibrosis of bronchiolar walls (that may even obliterate lumina). Smooth muscle hyperophy can be seen in larger bronchi, and is related to the increased effo needed to clear bronchi of copious amounts of mucus, but does not cause increased mucus production.Squamous cell metaplasia is seen as a reaction to irritation (often by smoking) in the larger bronchi. It is related to increased risk of squamous cell carcinoma in smokers, but not increased mucus production.Type I pneumocytes are the normal, flat, lining cells of alveoli. Ref: Chandrasoma P., Taylor C.R. (1998). Chapter 35. The Lung: II. Toxic, Immunologic, & Vascular Diseases. In P. Chandrasoma, C.R. Taylor (Eds),Concise Pathology, 3e.
Goblet cells
Smooth muscle cells
Squamous cells
Type I pneumocytes