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Something Smelly



  A thing has a smell because it gives off tiny bits of itself.  These bits are usually molecules.  When you smell a rose or a pizza or an onion or dog poop, it's because invisible molecules have floated off the thing and into your nose!   Perfumes are specially made to send lots of molecules floating into the air and into our noses.

Something To Smell With


When you breathe, you drag lots of things into your nose - including those smelly molecules!  But there's only a small part of your nose that works on figuring out what you're smelling. 


That part is a little patch of skin about the size of a penny high up inside your nose.  This little patch of sensory skin (called sensory because it's involved with the senses) have millions of little hair-like cells.  These cells are called  cilia (say, silly-ah).


The cell that looks blue is one of the cilia. 


These hairy little cilia cells are special:


They are sticky with mucus to catch things that blow by.  (Not all animals have cilia, but they always have something that will catch molecules.)


They are connected directly to your brain.


They can tell when something smelly sticks to them.  Then they send a message about the smell directly to your brain!



One reason dogs have a much better sense of smell than humans is that they have room for a lot more cilia inside their noses than we do!



A Brain To Figure Out What To Do

About the Smells


Humans have big  brains.  A human brain is made up of billions of cells.  These cells get messages from all over our bodies -- eyes, ears, mouth, skin, and nose.   Different kinds of messages go to different parts of our brain.  

There's a special section of our brain that handles smells.  When that part of the  brain figures out that the smell is pizza, it sends a message to another part of our brain:  "Delicious!"   But when we smell sour milk, our brain warns:  "It's yucky!  Don't drink it!"  


Smell is important to humans.  But it is much more important to most other animals.  Want to know more?  Come back soon!  We'll have another page for you!


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