What happens to the bronchi as they branch further into the lungs without cartilage?

As the bronchi branch further into the lungs, they undergo a transformation into smaller structures known as bronchioles. This process is characterized by a decrease in size and the progressive loss of cartilage in their walls. Unlike the larger bronchi, which are supported by cartilage rings that maintain their structure and prevent collapse, bronchioles are primarily lined with smooth muscle and elastic fibers, enabling them to regulate airflow to the alveoli—the sites of gas exchange.

As the bronchi continue to divide, they transition into these bronchioles, which are crucial for directing air deeper into the lung tissue where oxygen and carbon dioxide exchange occurs. The absence of cartilage allows bronchioles to be more flexible and responsive to changes in air pressure and volume during breathing. Consequently, understanding this transition is essential for grasping respiratory physiology and its implications in health and disease.