The sense of smell is a very powerful and special sense. Human nose has around 10 million smell receptors which can distinguish more than 10 trillion odours! Our olfactory cells have the unique ability to regenerate; and this amazing fact is helping scientists around the globe to understand more about anosmia (loss of smell), a condition now being associated with the COVID -19 infection.
We all have different responses to aromas, which get entangled with our memories. Often we remember those memories by associating them with these aromas!
Let us understand how this happens –
- The cell lining in the nose (nasal cavity) is called the Olfactory Epithelium l. These cells have cilia which possess olfactory receptors. When we smell, the odour molecule is dissolved in the olfactory epithelium and gets bound to the olfactory receptors.
- This initiates an impulse response that spreads to the olfactory sensory neurons, which then carry these signals from the receptors to the olfactory bulb. The olfactory bulb processes the impulse of odour.
- The mitral cells in the olfactory bulb carry these processed and filtered signals to the olfactory cortex, which allows us to recognize the particular aroma.
4.The mitral cells carry these signals to the limbic system as well. Some mitral cells are also directly connected to the Amygdala.
5.Hypothalamus, Hippocampus and Amygdala are the brain structures that collectively form the Limbic system. This system is involved in processing the emotions and memory, hence referred to as the ’emotional brain’. It also explains why certain aromas are linked to specific memories.
6.The Limbic system also has an effect on the cerebral cortex and the cerebellum. Hypothalamus has an influence over the pituitary gland in the brain. Pituitary Gland, in turn, has an influence on the endocrine system, which is involved in the hormonal secretion and hormone balance. Thus, the sense of smell and associated aromas have far reaching effects on our brain and body.
Essential Oils have specific chemical compositions which, when inhaled, travel by this olfactory pathway and evoke unique responses in every person. They help us handle our emotions in an efficient and positive way. They also affect various hormones in our body and can induce wonderful effects like calmness, relaxation, energized and positive feeling, enhanced concentration and memory power, and so on.
- Studies have shown that humans have about 396 olfactory receptor genes, while dogs have 811. Elephants are the mammals with the highest olfactory receptor gene count of 1948, followed by rats with 1207!
- Women have a better sense of smell as compare to men.