Which structure acts as the windpipe in the respiratory system?

The trachea serves as the windpipe in the respiratory system, providing a crucial passageway for air to travel from the throat into the lungs. This tube is lined with ciliated mucous membranes that help trap and expel particles and pathogens, thereby playing a vital role in protecting the lower respiratory tract.

The trachea is located beneath the larynx and branches into the two primary bronchi, which then lead into each lung. Its structural design, featuring C-shaped cartilaginous rings, ensures that it remains open and maintains a clear airway despite changes in pressure and movement during respiration.

Other structures mentioned, such as the alveoli, nasal cavity, and lungs, serve different functions, like gas exchange, filtering air, and housing the respiratory tissues, but they do not function as the main airway like the trachea does. Understanding the specific roles of these structures is essential for grasping how the respiratory system operates effectively.