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The Way The Sense of Smell Works in Humans..!!

Many people will assert that the sense of smell is the most important sense while evaluating wine. This is so because the olfactory organs play a vital role in aroma and flavor perception. Without the presence of olfactory system, all the wines would seem to be dull alcoholic solutions of sugar and acid. Hence, the smelling sense is by far the most potent of our senses.

Olfactory sense helps us distinguish between several hundreds of odors. The sense of smell is called ‘Olfaction’. This sense is related to memory which the brain can associate between an object and its smell. This is the way, we remember smells and also differentiate them with other smells. This article provides a brief account on the working of sense of smell in humans; read on for more information.

Sense of Smell

Working of the Sense of Smell in Man
There are several hundred kinds of smell in the world. The human body has a certain mechanism which enables us to distinguish between various kinds of smells. But before you know about the mechanism, first you must in brief know about the internal structure of human nose which will help you better understand the mechanism of sense of smell.

Internal Structure of Nose

  • Neurons are present in the internal nose, which are called ‘olfactory receptor neurons’.
  • The above receptor can come in contact with the air.
  • These neurons have cilia, which are hair like projections and help in increasing the surface area.
  • The cilia are covered with a mucus layer.
  • These olfactory receptor neurons are connected to the olfactory bulb that in turn is connected to orbitofrontal cortex.

This was all about the internal structure of nose in short.

Let us take an example to understand the mechanism of sense of smell –

  • Assume that bananas are kept on the table. Certain molecules of bananas which are volatile in nature get diffused in the air. These are termed odorant molecules.
  • The air containing these molecules reaches your nose when you inhale.
  • These molecules present in the air mix with mucus and when they come in contact with cilia, they in turn trigger olfactory neurons.
  • This trigger will send a signal to the olfactory bulb.
  • This bulb will then transmit the impulse to OFC (orbitofrontal cortex).
  • The orbitofrontal cortex will analyze the impulse pattern and identifies the molecule’s substance which has struck the cilia.
  • This analysis is then send to the brain.

This is all about how you identify a substance by just smelling.

Bad Smell or Good Smell

  • There are certain smells that are either good or bad ie., some smells you like and some that disgust you. Like, the smell of a perfume appeals you while the smell of rotten food seems awful to you and thus, we classify smells as either good or bad.
  • As per scientific reason, there is no differentiation between smells in terms of bad or good. The working of the olfactory receptors and the OFC are in the same manner for both kinds of smell.

So, how do we differentiate between various kinds of smells?
We know that the OFC and olfactory receptors work in the same manner, then how do we able to distinguish between several kinds of smell. The answer is quite simple. There is huge number of olfactory receptor neurons and each of them is encoded with a gene. Thus, on contact with air containing different kinds of molecules when come in contact with these different genes, each gene respond to the corresponding smell. Thus, the reason is simple that when you smell something, it is due to presence of gene for it.

smelling food

Facts About Olfaction

  • According to Researchers, those people having dominant nostril, either right or left are similar to the dominance of one’s hand either right or left. The smells are better sensed through the dominant nostril.
  • The receptors reduces the intensity of stimuli. Like, if we experience bad smell, we become repugnant. According to some Scientists, for lowering the intensity of stimuli, calcium cations are responsible.
  • Any substance having no volatile molecules can’t be smelt, that is why you can’t smell silver, gold and steel.
  • There are certain times, when only you can smell and not others. Those smells which only you can smell are generally not pleasant and they are termed as phantom odors. There is a condition called Phantosomia in which a person can sense a certain smell even when there is no generation of stimulus. This condition is caused by a person’s temporal lobe damage.
  • A man can differentiate between certain kinds of smell, but their smell sense is not acute as in animals.

This is all about the working of sense of smell in humans and this also proves that olfaction is the most wonderful sense present in humans. Excitingly, this sense is also related to the sense of taste and memory. You must also know that you can’t smell everything around you.

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