Final answer:
The terminal bronchi are called terminal bronchioles; they lead to respiratory bronchioles and then to alveolar ducts, ending in alveolar sacs where gas exchange occurs in the lungs.
Step-by-step explanation:
The terminal bronchi, also known as terminal bronchioles, are the smallest subdivision of the bronchial tree before reaching the structures of gas exchange in the lungs. They typically have a diameter of about 1 mm or less. These terminal bronchioles lead to respiratory bronchioles, which further subdivide into several alveolar ducts.
These ducts are attached to alveolar sacs, each containing multiple alveoli where the actual gas exchange takes place. The walls of the bronchioles have smooth muscle but lack cartilage, unlike the larger bronchi, allowing their diameter to change and thus regulating airflow.