Nose and Sinuses

The nose has 5 basic functions; respiration, filtration, phonation (what your voice sounds like,) olfaction (smell,)  and  immune response (1st line of defense against respiratory pathogens) First and most importantly, is to humidify and warm the inspired air. Also, as the air passes through, the nasal cavity removes airborne particles such as allergens, dust  and other debris before the air reaches the lower airways.

The lining secretes mucus that coats the passage and traps those particles.  It smells by capturing the odor bearing particles and relaying these signals to the olfactory recesses, and later to your brain where it interprets those signals as smells (and also contributes to your sense of taste). The main ventilation chambers are the sinuses which include the maxillary sinus, (paired behind the cheeks, small but present at birth,) the frontal, sphenoid, and ethmoid sinuses which develop as you grow. These cavities directly communicate with the nasal cavity.

The secretions from these sinuses drain into the nasal cavity but can become chronically inflamed or infected. Like the nasal cavity, the wall lining of the sinuses also secretes mucus. The hard palate or roof of your mouth is the floor of the nasal cavity.