Bronchi and bronchioles

Airways branch out in the trachea into left and right segments, which we call left and right bronchi. Bronchi subdivide into smaller segments connecting all airways into all five lobes of the lungs. The smallest parts of these branches are called bronchioles, which are a part of the lower respiratory system. The terminal parts of the bronchioles contain alveoli which is the place where gas exchange occurs.

Illustration of a human torso with a close look of the trachea, the lungs, and the bronchi. The trachea goes down the throat until it divides into two bronchi. Each bronchi is connected to a lung. Inside the lungs, the bronchi are separated into different bronchioles, which resemble the branches of a tree. At the edge of each bronchiole there are a group of alveoli, which are sphere-shaped.

Figure 1. Overview of the respiratory system with a detailed view of the bronchi.

Referred from:

Article

Structure of the respiratory system

Article

Lung volumes