Final answer:
The upper airway filters, warms, and moistens inhaled air and also plays roles in speech production and preventing food and liquids from entering the trachea.
Step-by-step explanation:
The function of the upper airway in mammals is primarily to filter, warm, and moisten the air that is inhaled before it reaches the lungs. The nasal cavity has hairs and a mucous membrane that trap large particles, like dust and pollen, protecting deeper tissues. The air that passes through is also humidified and brought to body temperature, which helps prevent damage to the lungs and trachea from cold, dry air.
Furthermore, the oral cavity serves as a secondary opening for the respiratory tract, while structures like the paranasal sinuses, the nasopharynx, and the larynx play roles in speech production, facilitating the movement of air to other parts of the system, and preventing food and liquids from entering the trachea through the epiglottis.