Tracheobronchial Tree With Lymph Nodes - Male, 28 Years

What Is the Tracheobronchial Tree?

The respiratory tract is divided into upper and lower airways. The upper airway contains the nose, sinuses and pharynx (the uppermost part of the throat). The lower airway is called the tracheobronchial tree to describe the highly branched system of tubes supplying air to the lungs. It includes the trachea, bronchial tubes and lungs.

The Lungs

The lungs are the largest organs in the lower respiratory tract. The right lung is larger than the left and has three lobes – upper, middle, and lower. The left lung has two lobes – upper and lower, and a small tongue-shaped structure called the lingula.

Bronchi and Bronchioles

The lower airway starts at the trachea, or windpipe, which connects to the lungs through a network of highly branched tubes. The trachea contains a series of C-shaped cartilage loops that help keep the airway open during breathing, starting with the cricoid cartilage and ending with the carina. This is where the bronchial tubes separate into the right and left lungs. Smaller, tree-like tubes called bronchioles connect to tiny air sacs called alveoli in the lungs. This is where the gas exchange involved in breathing occurs.

What Does the Tracheobronchial Tree Do?

When a person inhales, air travels down the trachea, through the bronchial tubes, and into the lungs. In the lungs, oxygen from the inhaled air is transferred into the blood and circulated throughout the body by a network of arteries and veins. When blood returns to the lungs, carbon dioxide (CO2) is exhaled to complete the process of breathing.