Explain5 marksStandard
A student examines microscopic slides of transverse sections of the trachea and a bronchiole from a human lung. They observe that the trachea has prominent C-shaped pieces of cartilage in its wall, with smooth muscle located only in the posterior region between the cartilage ends. In contrast, the bronchiole has no cartilage but a thick, complete layer of smooth muscle surrounding the lumen.
Explain how the distribution of cartilage and smooth muscle differs between the trachea and a bronchiole, and how these differences are related to the functions of these structures.