Sensory Systems/Olfactory System/Introduction

Probably the oldest sensory system in nature, the olfactory system concerns the sense of smell. The olfactory system is physiologically strongly related to the gustatory system, so that the two are often examined together. Complex flavors require both taste and smell sensation to be recognized. Consequently, food may taste “different” if the sense of smell does not work properly (e.g. head cold).

Generally the two systems are classified as visceral sense because of their close association with gastrointestinal function. They are also of central importance while speaking of emotional and sexual functions.

Both taste and smell receptors are chemoreceptors that are stimulated by molecules soluted respectively in mucus or saliva. However these two senses are anatomically quite different. While smell receptors are distance receptors that do not have any connection to the thalamus, taste receptors pass up the brainstem to the thalamus and project to the postcentral gyrus along with those for touch and pressure sensibility for the mouth.

In this article we will first focus on the organs composing the olfactory system, then we will characterize them in order to understand their functionality and we will end explaining the transduction of the signal and the commercial application such as the eNose.