Harrison's Internal Medicine Chapter 30. Disorders of Smell, Taste, and Hearing
The sense of smell determines the flavor and palatability of food and drink and serves, along with the trigeminal system, as a monitor of inhaled chemicals, including dangerous substances such as natural gas, smoke, and air pollutants. Olfactory dysfunction affects ~1% of people under age 60 and more than half of the population beyond this age.
Smell is the perception of odor by the nose. Taste is the perception of salty, sweet, sour, or bitter by the tongue.