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Your sense of smell, or olfaction, starts in your
nose. But, like your other senses, translating the
intake of chemicals into a sensory experience
happens in your brain.
Odors are essentially chemical compounds.When
the chemicals enter your nose, they dissolve in the
lining, ormucousmembrane. The 10million scent
receptors in your nose react to chemicals and
send a signal to the brain’s limbic system.
Because the limbic system also processes your
emotional behavior andmemory,many smells
often evoke powerfulmemories. Do any
scents bring backmemories for you?
Dogs haveanose for scents
Have you ever noticed that thefirst thing a dog
doeswhen itmeets you is give you a good
sniff?Dogs have extremely powerful senses
of smell, which they use to get infor-
mation. Like us, receptors in the nose
sendmessages to the brain—
but dogs have 200million
receptors, or about 20 times
more than humans!They also
have 40 timesmore scent-
processing cells in their brains
than humans do.
Scent-filled air stays in a dog’s nose
even after it exhales, so themolecules
linger long enough for a dog to
identify a scent. Dogs can remember
scents from days before. Because of their
keen sense of smell, dogs can help humans
findmissing people, detect drugs and bombs,
and even sniff out cancer cells.Whereas
a human can detect a faint scent of sugar
in coffee, a dog can detect a teaspoon
of sugar in a
million gallons
What’s that smell?
Try this activity tounderstandhow your senses of smell, touch
and tastework together.What youneed: Blindfolds; pieces
of three to eight fruits or vegetables, such as orange, carrot,
celery, cantaloupe, potato, apple, pear or banana, peeled
1. .Divide your friends into three groups, have themput
onblindfolds and explain that each group is to identify each
foodusing only one sense. Donot tell themwhich foods
you areusing.
2. Give the first grouppieces of food to identify by smell only,
and ask them towrite down their guesses.
3. Give the second grouppieces of food to identify by touch
only, and ask them towrite down their guesses.
4. Give the third grouppieces of food to identify by taste only,
and ask them towrite down their guesses.
Which groupof friendswas able to identify the foods
most easily?Why?
Which foodswere the easiest to guess?Why?
Which foodswere the hardest to guess?Why?
Our scent receptors are sensitive
to seven types of sensations:
Camphor •Musk • Flower
Mint • Ether •Acrid •Putrid
Smell is the first
sense youusewhen
1,2,3,4,5 7,8
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