GLOSSARY

The upper respiratory tract comprises the parts of the respiratory system above the cricoid cartilage (and outside the thorax): the nose and nasal cavity, paranasal sinuses, pharynx, and larynx.

Functions

• Conducting air to the lower airways.
• Conditioning air: warming it to about body temperature and humidifying it to near 100 percent humidity, mainly in the nasal cavity.
• Filtering: trapping particles larger than about 10 micrometres.
• Smell: in the roof of the nasal cavity.
• Airway protection: the epiglottis and the cough reflex.
• Voice production and resonance.

Clinical Application

Upper respiratory tract infections (URTIs) such as