The Biological Importance of Smell

What would life be like without the ability to smell? Although this might not be a question asked every day, it is definitely something to think about because for most people, the sense of smell is automatic.

However, if it was removed, things would change dramatically. From the warning of dangers to the enjoyment of foods, your nose is very important.

How the Sense of Smell Works

As part of the chemical senses, the sense of smell is generated when the brain receives messages from sensory cells located in the nose. The cells are called olfactory sensory neurons and they exist within a small patch of tissue, high up in the nose, and connecting to the brain. Every olfactory neuron has one odor receptor, and collectively, they are stimulated by the microscopic molecules released by things around us.

For example, if you are in a bakery, the molecules projected by the bread would be detected by the neurons. Then, the neurons send the signal to the brain and it is identified as the smell of freshly baked bread. Of course, there are more smells than there are receptors, so a combination of receptors might be required to correctly identify the actual scent. Once our brain registers the smell, it is stored, and later retrieved when that smell is encountered again in the future.

Besides the pathway through the nostrils, smells can be transported to the olfactory sensory neurons by a second pathway. In this instance, a channel that connects the roof of the throat to the nose picks up the smell when food is chewed. Since the channel is connected to the nose, the olfactory neurons can sense the aroma.

There is a common chemical sense that also triggers our sense of smell. Particularly on the moist surfaces of the nose, eyes, throat, and mouth, thousands of nerve endings sense various smells. These scents are usually strong, such as an onion, which can cause the eye to tear as a result.

Why Smell is Important

Smell and taste are two senses that work together, especially when eating foods. If a person has a cold and their nasal passages are blocked in any way, it could interfere with their ability to taste. The channel that connects the throat and the nose would not be delivering the smell to the olfactory sensory neurons as normal, leading to a reduced taste of the foods being chewed.

At times, the sense of smell and the sense of taste can be confused. When a person has a smell disorder that is preventing them from tasting foods, they might be surprised to learn that it is not due to a loss of taste. The sense of smell typically returns after the illness subsides and foods are enjoyed much more.

Acting as an alert to possible danger, our sense of smell is frequently the first warning sign for various risks, including fires, chemical or gas leaks, and spoiled foods. Without it, we might not receive the advance warning, and certain safety precautions would not be taken. People living with smell disorders should consult with their doctor to find out how to compensate for their lack of smell.

Fortunately, most smell disorders can be cured. Smoking, colds, and injuries are among the number of causes of smell disorders. Research has shown that specific illnesses, such as Alzheimer’s disease and Parkinson’s disease have been linked to smell disorders as well. In fact, a reduced or removed sense of smell can even be used as a possible method for early detection of these diseases.

A smell disorder might also be a side effect of medication. The U.S. Food and Drug Administration has recently issued a warning against a certain line of cold remedies that appeared to interfere with the sense of smell. If you have a reason to suspect a loss of smell, it is highly recommended that you check with a specialist as soon as possible.

References

1. ^{^} HelloLife™ Home (www.hellolife.net)
2. ^{^} Know Your Nose: The Biological Importance of Smell (www.hellolife.net)
3. ^{^} http://www.nidcd.nih.gov/health/smelltaste/smell.html#smell_02 (www.nidcd.nih.gov)
4. ^{^} http://www.fda.gov/ForConsumers/ConsumerUpdates/ucm166931.htm (www.fda.gov)
5. ^{^} http://www.sciencedaily.com/releases/2010/06/100611204139.htm (www.sciencedaily.com)