Which of the following changes occurs as the conducting tubes of the lungs become smaller?

A) Cartilage rings are gradually replaced by regular plates of cartilage.
B) Resistance to air flow decreases due to the increased number of tubes.
C) Smooth muscle amount increases.
D) Lining of the tubes changes from ciliated columnar to simple squamous epithelium which lines the alveoli.


Answer: C) Smooth muscle amount increases.

Anatomy & Physiology

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