Final answer:
The respiratory tract passageway that leads into each lung is called the bronchus, which then divides into smaller bronchioles, ending in alveoli for gas exchange.
Step-by-step explanation:
The name of the respiratory tract passageway that leads directly into each lung is the bronchus. After air moves into the trachea, or windpipe, it reaches the chest, where the trachea divides to form the right and left bronchi. These bronchi are made of cartilage, which helps prevent collapse, and are lined with mucus and cilia that trap particles and move them toward the throat to be expelled. The bronchi further divide into smaller passages called bronchioles, which eventually lead to the alveoli responsible for gas exchange.