Final answer:
The two regions in the respiratory system are the external nose and the nasal cavity.
Step-by-step explanation:
The nose and paranasal sinuses in the respiratory system are divided into two regions: the external nose and the nasal cavity.
The external nose refers to the visible part of the nose on the outside of the face. It includes the nostrils or nares.
The nasal cavity is the internal part of the nose. It is a large, air-filled space in the skull. The nasal cavity is divided into left and right sections by the nasal septum and contains structures like conchae and meatuses that help filter, warm, and humidify inhaled air.