Which structure serves as a pathway for air to enter the lungs?

The nasal cavity serves as a primary pathway for air to enter the lungs. When air is inhaled through the nose, it passes through the nasal cavity, where it is warmed, moistened, and filtered. This structure plays a significant role in the respiratory system, as it directs the airflow toward the pharynx and subsequently to the trachea, and ultimately the lungs.

The soft palate is involved in separating the nasal cavity from the oral cavity but does not function as a direct passage for air. The alveoli are the tiny air sacs in the lungs where gas exchange occurs, but they are not involved in the initial movement of air into the lungs. The glottis is the opening between the vocal cords in the larynx, primarily involved in sound production and protection of the airway during swallowing, rather than serving as a primary pathway for airflow. Thus, the nasal cavity is crucial for effectively channeling air into the respiratory system.