Smell

The sense of smell is innate. It is an unconscious activity that has a great effect in the body’s physiology. Smell is also strongly connected to memory. For example, if during a very bad experience, you smelled onions, you forever associate the smell of onions with bad experiences.

Anatomy of Smell

The sense of smell occurs in the olfactory epithelium that occupies a small area in the roof of the nasal cavity. Olfactory nerves are sometimes described as “brain cells outside the brain”. The nerves are connected directly to the limbic system. This results in the immediate understanding of smells by the brain.

The inside of the nose is moist. It is the moisture that dissolves particles of aromatic vapor. Each olfactory cell has several fine filaments called cilia. The tips of the cilia have receptor shapes that fit with the dissolved molecules of scent.

The scent information is then transmitted from the cilia to longer nerve cell fibers and is taken directly to the limbic system of the brain. The limbic system controls the involuntary aspects of our bodies and registers emotions, pleasure, pain, fear, anger, sorrow and sexual feeling.

Other cells of the olfactory epithelium include the columnar supporting cells and basal cells. Basal cells continually divide to produce new olfactory receptor cells. The replacement of olfactory cells is unusual since most other nerve cells cannot be replaced.

The mucus that lines the olfactory epithelium is produced by olfactory glands that occupy the connective tissue above the olfactory epithelium.

Conditions that can Affect Smell

There are many medical and non-medical conditions that can cause the loss of smell. Some of these include:

• Normal aging
• Upper respiratory infections,
• Rhinitis,
• Common cold,
• Allergies,
• Hay fever,
• Sinusitis,
• Nasal tumor,
• Smoking,
• Formaldehyde

The sense of smell is very sensitive to small changes in our environment. Scent also affects our emotions and brain waves. It has been shown that scents can affect the pulse rate blood circulation and breathing. This is probably why the fragrance industry is one of the biggest in the world.

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