Sunday, January 18, 2009

Jeffrey, The Secret of Scent

Many of us take for granted the sense of smell. We know we can smell things, but we don’t really know why and we don’t really care. However, our sense of smell plays a much more intricate part of our life than we may like to believe. Let’s examine how this sense works. If you were to ask someone to smell something, they would most likely put their nose close to the object or bring the object close to their nose and breathe in the air around it. I don’t think you’re going to see anyone shove the object in their nose or inhale liquid through their nostrils. Yet, one still stands to wonder, how does the nose receive scent? The nose has receptors located in the nasal passage just below the eyes. These receptors are in fact, large molecules themselves, and they receive the gaseous molecules you inhale. Specifically, we have over a thousand different odor receptors in our nose. Each one corresponds to a certain size and characteristic of a gaseous molecule. When we inhale these molecules, the receptors receive them and send an electric signal to the brain. The brain then interprets this signal as smell. Flowers have many different gaseous molecules and they stimulate various odor receptors. However, the gaseous molecules must be able to dissolve in water or at least be somewhat soluble. This is because the odor receptors, themselves, have a thin water membrane surrounding them. If the molecule is unable to dissolve at all in water, then it is practically impossible for our noses to receive its smell. These odor receptors also play a big part in our emotions, memory, sexual, and maternal behavior. We connect specific scents to different memories or feelings and when we smell them, these memories come flooding back. Today, scientists are experimenting on the sense of smell and how pheromones are linked to our choice of a sexual partner. Scientists have found that dogs have a much larger number of odor receptors in their nose. This explains why they are used in missing persons’ cases, drug busts, and searching for explosives.

Unknown Terms:

Solubility- A substance’s ability to be dissolved in a given amount of solvent.

Pheromones- A chemical secreted by an animal that influences the behavior or development of others of the same species.

This is a really interesting article. It is not every day you wonder what’s really going on when you smell that cup of coffee or fresh cut grass. Many people only focus on our senses of sight and hearing, imagining how terrible it would be to lose them. It would be just as terrible to lose your sense of smell and it actually is quite possible. Think about your favorite food and what it would be like if you could see it before you and you could taste it, but you couldn’t smell it. Imagine all of your favorite scents and what would happen if one day you woke up and they were gone. It would be very hard to live without it. I also found the part about pheromones very interesting. I have always been fascinated by this topic. The thought that our sense of smell plays a part in our choice of a partner is really interesting. Scientists are finding that pheromones may be linked to genetics. They haven’t found any conclusive evidence yet, but it is possible. Martha McClintock, a researcher at the University of Chicago, found a link between a chemical given off by women that caused synchronization of menstrual periods. She was living in an all female dormitory and many of the girls came in with scattered menstrual cycles, but as the year went on they found that their cycles were coming at the same time. I find that astonishing. To think that their pheromones are powerful enough to affect each other’s menstrual cycles. We have so much more to learn in this field and I’m anxious to see what kind of research we will find in the near future.


Colin Baird, 2.5 We smell substances by responding to evaporated molecules, Chemistry in Your Life, W.H. Freeman and Company, New York, 2006

Maya Pines, Pheromones and Mammals, Howard Hughes Medical Institute (HHMI), 2008

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