How does the sense of smell work?
By Ryan. K
2012

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Figure 1 This woman is smelling a flower. The reason that she can smell it is that it is a volatile-solid. If it wasn’t a volatile-solid she wouldn’t be able to smell it
You smell things from the odorants that come from it. Every item has molecules that from it (Could be flowers or fruit or pool water). Though every item gives out molecules, the ones that smell are the ones with volatile molecules. Steel blocks have no smell because they have no volatile molecules. It is a non-volatile solid. The nose has 2 cavities; Separated by a wall of cartilage, this wall is called the septum. The noses exterior openings are called the nostrils or sometimes called the nares. The shape of this nasal cavity is very intricate and complex.












How your smell actually works

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Figure 2 A homemade Diagram showing how the humans sense of smell works and the process
The nose has 2 jobs, breathing and smelling. Both of these happen when the air goes through your nostrils. When you breathe the air goes to your up through your nasal cavity and into lungs but the molecules in which you smell go through the nasal cavity too but then evaporate in the mucus at the top of your nasal cavity. This happens because your nostrils are lined with mucus. At top of each nasal cavity there’s a little patch of mucus that is about the size of a stamp. These patches each contain somewhere near five million receptor cells called olfactory neurons. Each of these has cilia which is the small hair that takes in the molecules. Each receptor cell is built to receive a smell. It is kind of like a lock and combination; you have to find the right combination to open the smell. Once this has been done they form into electrical signals and goes to the olfactory bulb. The olfactory bulb is a part of the brain that is connected to the brain but receives in the nasal cavity. The olfactory bulb is shaped like a miniature cucumber. It sends these electrical smell messages straight into the olfactory cortex. This is the most direct avenue of any sense.














Comparison between taste and smell
When you have a cold you can’t taste as well. Do you know why? It is not your taste buds fault, it is because of your stuffed up nose. Your sense of smell is 75% of what you taste. Scientists call smell distance chemoreception and taste contact chemoreception. They call taste contact chemoreception because you come in contact with the chemicals. They call smell distance chemoreception because you are getting the chemicals from a distance. When you eat the molecules dissolve in the mucus at the top of your nasal cavity just like your smell.Taste is 1 of the 5 senses. The 5 senses are smell, taste, touch, sight, and hearing



How humans smell is different from other animals
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Table 1 A homemade Table showing the difference between a human’s nose and the noses of types of dog’s.




The way air breathing anmals primarily smell is by the epithelium. These chemically sensitive nerves catch the molecules in the nasal cavities and that is what you smell. Mammals that are carnivores that rely on smell a lot find their prey have, complicatedly curled turbinal bones that enhance the epithelium. This makes their sense of sell much greater than humans. Human’s sense of smell is much duller because their turbinal bones are as complicated and curled. Dogs smell is much greater than that of a human. For instance look at the graph, bloodhound have 60 times as many scent receptors as humans, that is like saying bloodhounds smell is 60 times greater than humans. That is a lot.














Glossary


  • Epithelium-chemical sensitive nerves that line of the nasal cavities
  • Odorants- the molecules that float around in the air that you smell, the molecules that come from it
  • Volatile-solid-a object or thing that you are able to smell

Citations

"How Does the Sense of Smell Work?" Discovery Health. N.p., n.d. Web. 24 Sept. 2012.

‘nose." Encyclopædia Britannica. Encyclopædia Britannica Online School Edition.

Encyclopædia Britannica, Inc., 2012. Web. 14 Sept. 2012.


"smell." Encyclopædia Britannica. Encyclopædia Britannica Online School Edition.


Encyclopædia Britannica, Inc., 2012. Web. 13 Sept. 2012.


Walker, Richard. The Children's Atlas of the Human Body : Actual Size Bones, Muscles, and Organs in Full Color, Brooke Field : Millbrook Press , 1994. Print.


Weiss, Ellen. The Sense of Smell. New York: Children's, 2009. Print.