How Do We Distinguish Odors?

It is truly difficult to imagine the world without our sense of smell. Sure, we may be afflicted by a stuffy nose every now and then, but imaging the world entirely without any smells or odors is indeed a very strange thing. However, even though smell plays a major role in our lives everyday, we do not often stop and take the time to think about how exactly those smell signals are able to be so well represented in our brains. Even though we can perceive so many different smells, the system that handles that processing does so without so much as a moment's hesitation.

Although there are a variety of ways that our sense of smell could be explained, perhaps the first thing that we need to do is to group it with our sense of taste. Although we often think of these two together, they are actually connected, and it is a very interesting connection indeed. Unlike our senses of touch, vision and hearing, we cannot hear and taste without stimulation of some kind. For those reasons, smell and taste are commonly referred to as "chemical senses", as they require some sort of chemical in order to create a signal.

The sense of smell is referred to as our "olfactory" sense, which will make much more sense in just a short time. Note that sense of smell differs greatly between different people, as some may have a very developed sense of smell while others may be unable to tell one odor from the other. Also, age range has a definite effect on sensory input, either teenagers or the middle aged have a much easier time detecting odors, and females are generally better than males.

However, when it actually comes to interpreting smells, the way in which we do it is universal. First, think of your nose. Within the nose is the nasal passage and what is known as the "olfactory nerve track". Think of this track as a multi-layered device. At the bottom is a mucous layer and the nerve endings for the olfactory receptors. Above the mucus is the actual cell body of the receptor, and following that is the bony plate that separate the nerves from the olfactory bulb.

When you smell something, the individual odor molecules enter the nasal passage and find their place among the receptors in the nerve tract. This operates similarly to putting a key into a lock, certain types of molecules only fit into certain receptors. It is for this reason that we experience different smells as we do. When the molecules "lock up" with the receptors, a signal is sent to our brain. There are two possible ways that this signal will eventually make it to the brain. The information can either pass through the thalamus, giving it a direct pathway, and explaining why we experience smells so quickly while senses can sometimes take a moment to register. The other possible pathway runs through the limbic system. The limbic system is closely tied to emotional responses, and this may be one of the reasons that certain smells cause so much discomfort or disgust. However, it can also be the reason why familiar smells (such as a particular perfume or cologne) can trigger memories so rapidly.

Although we do not often take the time to think about how experience the world as we do, understanding the sense of smell is very interesting indeed. While smell may not be the most complicated thing that goes on inside the human body, the scents we smell definitely impact the world as we know it and definitely affect life as we live it. If we simply take a little bit of time to learn how our own bodies work, we are better able to enjoy the many intricacies of life, and even though smell may seem like such a simple thing, it is surprising how much more we can come to appreciate the many smells around us when we better learn how our noses and our brains work together to produce the sense that we know as smell.