Air normally enters respiratory system via nostrils, or nares, which open into nasal cavity. The nasal vestibule (entryway) of the nose is guarded by hairs that screen out large particles.
Incoming air flows through the nasal meatuses (narrow grooves) and bounces off the conchal surfaces.
The hard palate separates the oral and nasal cavities. The soft palate separates the superior nasopharynx from the oral cavity. The connections between the nasal cavity and nasopharynx represent the posterior nasal apertures.
SUMMARY - The Pharynx
The pharynx is a chamber shared by the digestive and respiratory systems. The nasopharynx is the superior part of the pharynx. The oropharynx is continuous with the oral cavity; the laryngopharynx includes the narrow zone between the hyoid and entrances to esophagus.
What are the three subdivisions of the pharynx?
The three subdivisions are the nasopharynx, oropharynx, and laryngopharynx.
What is the function of the nasal conchae? How does this affect the lower respiratory system?
The conchae cause turbulence is the inspired air. This slows air movement and brings the air into contact with the moist, warm walls of the nasal cavity. Turbulent airflow is essential for filtering, humidifying, and warming air and creating currents that bring olfactory stimuli to the olfactory sensory neurons. If the nasal cavity where a tubular passageway with straight walls, turbulence would be minimal.
