Which of the following is NOT considered a part of the airway system?

The digestive tract is not considered a part of the airway system because its primary function is to process and transport food, not air. The airway system is specifically involved in the passage and regulation of air in and out of the respiratory system.

The upper and lower airways comprise various structures that facilitate respiration. The upper airway includes the nasal passages and throat, which serve to filter, warm, and moisten the air entering the lungs. The lower airway includes the trachea, bronchi, and bronchioles, which further conduct air to the lungs for gas exchange.

Sinuses, although primarily involved in functions related to voice resonance and the humidification of air, are also associated with the upper airway system. They play a role in respiratory health and can affect airflow and pressure within the upper respiratory tract.

Since the digestive tract serves a completely different purpose—supporting digestion rather than respiration—it is clearly distinct from the components of the airway system.