Lit Review: Your sense of smell

Have you ever wondered what you smell when you "smell" What makes a smell is something that is too small to see with your eyeball alone. It is even too small to be seen with a microscope! What you smell are tiny things called odor particles. Millions of them are floating around waiting to be sniffed by your nose!
You smell these odors through your nose which is almost like a huge cave built to smell, moisten, and filter the air you breathe. These little hairs are called cilia and you can pretend that they sweep all the dirt out of the nasal cavity, which is the big place the air passes through on it's way to the lungs. After passing through the nasal cavity, the air passes through a thick layer of mucous to the olfactory bulb. There the smells are recognized because each smell molecule fits into a nerve cell like a lock and key. Then the cells send signals along your olfactory nerve to the brain. Our sense of smell is connected really well to our memory.


Sense-Sational Facts

• Dogs have 1 million smell cells per nostril and their smell cells are 100 times larger than humans!
• Humans use insect warning chemicals, called pheromones, to keep away pesky insects!
• People who cannot smell have a condition called Anosmia.
• As you get older, your sense of smell gets worse. Children are more likely to have better senses of smell than their parents or grandparents. If your nose is at its best, you can tell the difference between 4000-10,000 smells!
  

Reference: http://library.thinkquest.org/3750/smell/smell.html