What structures are responsible for directing air from the trachea into each lung?

The structures responsible for directing air from the trachea into each lung are the bronchi. The trachea divides into two main bronchi, one for each lung. This branching occurs at a region known as the carina. The bronchi then continue to branch into smaller bronchi and eventually into bronchioles, which lead to the alveoli where gas exchange occurs.

The bronchi have a similar structure to the trachea, featuring cartilage rings and lined with respiratory epithelium, which helps in keeping the airways clear of mucus and debris. This structural design ensures that the air entering the lungs is directed properly, allowing for efficient ventilation and gas exchange.