Your Olfactory System 101

We all know that our nose is the main airway for our respiratory system. It
is also an important sense organ and a primary partner for aromatherapy.
The following diagram shows the location of the primary olfactory region.

In simple terms, the olfactory epithelium is a postage-stamp sized patch of
nerve cells with hairy projections. These projections are covered with
fine-tuned receptors sensitive to odor molecules in the air. There are
probably 10 million receptors, of at least 20 different types. When the
receptors detect an odor, they send nerve signals along the olfactory nerve
to the smell center of the brain, the olfactory cortex or limbic system
where the scent is catalogued and identified.

The limbic system initiates responses necessary for survival, such as hunger
and thirst. It also influences emotions, visceral responses to emotions,
motivation and mood. It is functionally associated with the hypothalamus
(often called the motivational area) which has control over the body's
automatic processes and the thalamus (the brain's information relay system).

The olfactory receptor cells innervate (stimulate to action) mitral cells in
the olfactory bulb. The olfactory innervation of the limbic system is
exceptional in that it represents the only sensory system that directly
innervates areas of the cortex.

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