Which structure is NOT part of the upper respiratory tract?

The trachea is correctly identified as NOT being part of the upper respiratory tract. The upper respiratory tract consists of the nose, pharynx, and larynx, which are responsible for filtering, warming, and humidifying the air we breathe before it moves into the lungs. The trachea, on the other hand, is a part of the lower respiratory tract; it connects the larynx to the bronchi and serves as a passage for air to enter the lungs. Understanding the anatomical distinction between the upper and lower respiratory systems is critical for grasping how respiratory infections, airflow, and various respiratory conditions can occur and are treated.