Structure and Function of the Trachea and Bronchi

What type of epithelium lines the trachea?

Ciliated, mucus-secreting, pseudostratified columnar epithelium.

What is the function of the cilia in the trachea?

They propel mucus laden with dust particles and debris away from the lungs and toward the throat.

What are the C-shaped cartilaginous rings in the trachea for?

They reinforce the trachea walls to maintain an open passageway and allow the esophagus to expand when swallowing.

What are the main bronchi further divided into?

Lobar (secondary) bronchi.

What do lobar bronchi branch into?

Segmental (tertiary) bronchi.

What are passages smaller than 1 mm in diameter called?

Bronchioles.

What do terminal bronchioles branch into?

Two or more respiratory bronchioles.

What happens to the amount of smooth muscle as respiratory tubes get smaller?

The relative amount of smooth muscle increases as the amount of cartilage declines.

How does the epithelium change in the bronchioles?

It changes from pseudostratified columnar to columnar and then to cuboidal in terminal and respiratory bronchioles.

What is the continuous branching of the respiratory passageways in the lungs referred to as?

The bronchial tree.

What do respiratory bronchioles subdivide into?

Several alveolar ducts.

What do alveolar ducts terminate in?

Alveolar sacs.

What are alveoli composed of?

A single thin layer of squamous epithelium overlying a basal lamina.

What covers the external surfaces of the alveoli?

A network of pulmonary capillaries.

What forms the respiratory membrane?

The alveolar and capillary walls and their fused basement membranes, also called the blood air barrier.

What is the diameter of terminal bronchioles?

Less than 0.5 mm.

What is the structure of alveolar sacs compared to?

Clusters of grapes.

What is the primary function of the trachea?

To provide an open passageway for air to enter and exit the lungs.

What is the role of the pulmonary capillaries surrounding the alveoli?

They facilitate gas exchange between the air in the alveoli and the blood.

What happens to the cartilage in the walls of bronchi as they become smaller?

The cartilage gradually disappears.

What is the significance of the bronchial tree structure?

It allows for efficient air distribution throughout the lungs.