The trachea conducts air to the two main bronchi, which are similar to the trachea histologically. Examine the diagram of trachea and major bronchi.

Examine the section the slide of trachea identifying the cartilage of the tracheal rings.

• In the respiratory epithelium, note especially the cilia and the thick basement membrane.

What is the function of the rings of hyaline cartilage?

Why are they made of hyaline rather than elastic cartilage?

What is the muscle type in the trachealis muscle and what function does it serve here?

Examine the H&E-stained transverse section of trachea  and identify the major layers.

• Note the abundant sero-mucous glands, the ring of cartilage, and the trachealis muscle on the posterior side. Examine the respiratory epithelium carefully.

How do the ciliated cells and the goblet cells work together in a protective function?

On to the lung.