How does the sense of smell work?


Today we are going to learn how the sense of smell works.  If you are wondering why an aromatherapist would care, head over to my previous post for a quick primer. Don’t worry, I’ll wait.

Now, let’s get into some granularity and talk about how the sense of smell works.  This is one of those topics that really sets professionals apart and illustrates their training.

So how does the sense of smell work?

 In the interest of time I will simplify this quite a bit.  Molecules are inhaled through the nose (essential oils, perfumes, nasty odors, they are all molecules of something).  The information is carried via an odor molecule which is turned into an electrical signal in the sensory neurons.    Olfaction, the ability to smell, and translate odors to electrical signals, is pivotal to the animals’ ability to find food and locate mates.  

In humans, our olfactory systems are rather elementary compared to other animals but it is still important for gathering information.  Odors and pheromones are translated into those electrical signals, conveying messages to the brain that elicit some type of response.  Odors are detected in the nose in the nasal olfactory epithelium (OE).

Animals detect pheromones via the VNO, the vomeronasal organ.  Some scientists believe that the VNO is an inactive organ in humans and that humans simply do not communicate via chemosignals.   Others know that scientific evidence proves this very concept.  Numerous tests have shown that when exposed to the smell of mens’ sweat, women’s physiological responses demonstrated statistically significant changes, classifying the sweat, or components of it, as pheromones.

Okay so we smelled something, the molecule was absorbed by the mucous membranes in our noses and were translated into electrical signals that are sent to the brain.  Then what? The olfactory passageways sent information to the olfactory cortex, located at the base of the frontal lobe of the brain.  Yep, what you smell is translated into a signal that is sent right to your brain.  From there it can be routed all over your brain, into various areas with various functions. The key to remember is that the brain controls things such as emotions, pain, memories, and a lot of other things. This is why aromatherapy can have both physical and psychological impacts.  If you are really fascinated by the science, there are plenty of courses online.  For our purposes, you get the picture.

Given that an essential oil has the power to communicate messages to the brain and those messages may cause a physical, mental, or emotional response, can you see why it is so important for an aromatherapist to understand olfaction?

Interested in learning more? My next post will be all about pheromones.



Sense of Smell Institute. (2009). Human Pheromones: What’s Purported, What’s Supported. [White paper].Retrieved from