Explain5 marksStandard
A student examines transverse sections of a human trachea and a bronchiole under a light microscope. The student notes the following:
- The wall of the trachea contains C-shaped rings of cartilage and a noticeable layer of smooth muscle connecting the open ends of the cartilage rings.
- The wall of the bronchiole contains no cartilage but has a relatively thick layer of smooth muscle.
Explain how the distribution of cartilage and smooth muscle in the trachea and bronchioles is related to the functions of these airways.