BIOL 221 Lecture Notes - Lecture 7: Bronchus, Smooth Muscle Tissue, Bronchitis
3 Mar 2020
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Document Summary
There are two primary bronchi; one extends to each lung. The walls have abundant cartilage with some smooth muscle. They are lined with pseudostratified ciliated columnar epithelium containing numerous goblet cells. The left is longer and narrower than right because it has to reach around the heart. Objects that reach the level of the primary bronchi are more likely to lodge in the right than in the left primary bronchus. Secondary bronchi serve the lobes of the lungs and are sometimes called lobar bronchi. They have less cartilage and more smooth muscle. Smooth muscle is found between the epithelium and the cartilage. The pseudostratified ciliated epithelium in these is lower in the secondary bronchi. Tertiary bronchi, also called segmental bronchi, carry air to the bronchopulmonary segments. They have irregular rings of cartilage and much more smooth muscle. The short pseudostratified ciliated epithelium is even shorter in these.
