Why Inhale? The Power of Olfaction
The Olfactory System
The Olfactory System (sense of smell) is unique. It's the only sense that has a direct path to the limbic system, specifically the amygdala (the “emotional” and “pleasure center” part of the brain). It only takes one synapse to reach the amygdala, whereas other methods, such as through skin penetration, require multiple synapses to reach the brain. The faster the message, the stronger the effects! The olfactory epithelium (a special epithelial tissue inside the nasal cavity) is only about 1” wide, yet it contains 2~5 million olfactory receptor cells (6~10million total in nasal cavity!). These receptors are chemoreceptors, meaning they create a chemical signal into a nerve impulse. Dendrites, one of the two olfactory sensory neurons, project directly onto the surface of the nasal cavity membranes in hair-like nerves called cilia. They are in direct contact with the outside world, the only part of the human body that has such exposed neurons.
Once the message gets initiated in the olfactory bulb, which sits above the olfactory epithelium, the message is passed through the olfactory tract, and then into the limbic system, beginning with the amygdala. The role of the amygdala includes emotion, emotional behavior, motivation, memory, and autonomic control of the body. Simply, our sense of smell has direct access to the amygdala and therefore can potentially interrupt the stress response, decreasing the potential magnitude of the body’s rapid involuntary response to a stressful situation.
The olfactory stimuli also influence other parts of the limbic system, such as the hypothalamus, hippocampus, and as a result, influence the entire body.
All the limbic parts are connected to each other, and essential oils have profound effects on the whole limbic system.