Aromatherapy Associates

The Sense of Smell

• The sense of smell is the most primitive of all our senses, and it is linked to some of the oldest and deepest parts of the brain.
• The physical structures of smell found in the nose and brain are together called the Olfactory System.
• The sense of smell is a dynamic sense; its effect is not constant but immediate, and then it fades.
• Aromas can trigger emotional and even physical responses, and allow vivid memory recall of people and places.
• Aromatic molecules are volatile, meaning that they become gases and spread quickly. We can then inhale them with the air we breathe, which is the first step to detecting an aroma.
• Once we have breathed in aromatic molecules they reach the top of the nose and the Olfactory Epithelium, where they come into contact with specialised nerve cells called Olfactory Cells.
• Olfactory Cells have tiny hair-like Cilia hanging from them, and aromatic molecules connect with these Cilia using a 'lock and key' process. This means each cilium will only recognise a specific aroma.
• When the molecules connect with the Cilia, the Olfactory Cell produces a nerve impulse which will travel towards the brain. The molecules will then break down and be washed away, leaving the Cilia free to detect any new aromas.
• The nerve impulse is carried from the Olfactory Cells to the next group of cells which make up the Olfactory Nerve. This nerve carries the message into the brain itself.
• The nerve impulse now reaches the Limbic System, one of the most primitive parts of the brain concerned with survival, instincts and emotions. Scientists think the activity of the nerve signals passing through this region could cause mood change by altering brain chemistry. This could be how aromas cause emotional responses.