ABSTRACT
To understand the pathological process affecting the nose and the paranasal sinuses, it is important to have an understanding of the normal physiological functions of the nose. The principal physiological function of the nose is to humidify and warm inspired air, as well as to remove noxious particles from the air, thus protecting the delicate distal lower respiratory tract. The paranasal sinuses are air filled cavities found in the maxilla, sphenoid, ethmoid and frontal bones. They develop from an outgrowth of the nasal cavity, and hence pathology affecting the nose also affects the paranasal sinuses. Nasal blood flow plays a crucial part in the normal physiological function of the nose. Two main mechanisms, the hydrostatic pressure of blood and the autonomic nervous system influence nasal mucosal vessel capacitance. Studies have shown that eight hours after exposure to tobacco smoke the efficiency of mucociliary clearance had reduced, with heavier smokers having more marked impact.
