A big batch of cookies coming out of the oven. Your gym bag full
of dirty clothes. How do you smell these smells and thousands more?
It's your nose, of course.
Your nose lets you smell and it's a big part of why you are
able to taste things. The nose is also the main gate to the
respiratory system, your body's system for breathing. Let's
be nosy and find out some more about the nose.
Nose Parts
The nose has two holes called
nostrils
. The nostrils and the nasal passages are separated by a wall
called the
septum
(say:
sep
-tum). Deep inside your nose, close to your skull, your septum is
made of very thin pieces of bone.
Closer to the tip of your nose, the septum is made of
cartilage
(say:
kar
-tul-ij), which is flexible material that's firmer than skin or
muscle. It's not as hard as bone, and if you push on the tip of
your nose, you can feel how wiggly it is.
Behind your nose, in the middle of your face, is a space called
the
nasal cavity
.
It connects with the back of the throat. The nasal cavity is
separated from the inside of your mouth by the palate (roof of your
mouth).
Getting the Air in There
When you inhale air through your nostrils, the air enters the
nasal passages and travels into your nasal cavity. The air then
passes down the back of your throat into the trachea (say:
tray
-kee-uh), or windpipe, on its way to the lungs.
Your nose is also a two-way street. When you exhale the old air
from your lungs, the nose is the main way for the air to leave your
body. But your nose is more than a passageway for air. The nose
also warms, moistens, and filters the air before it goes to the
lungs.
The inside of your nose is lined with a moist, thin layer of
tissue called a
mucous membrane
(say:
myoo
-kus
mem
-brayne). This membrane warms up the air and moistens it. The
mucous membrane makes mucus, that sticky stuff in your nose you
might call snot. Mucus captures dust, germs, and other small
particles that could irritate your lungs. If you look inside your
nose, you will also see hairs that can trap large particles, like
dirt or pollen.
If something does get trapped in there, you can probably guess
what happens next. You sneeze. Sneezes can send those unwelcome
particles speeding out of your nose at 100 mph!
Further back in your nose are even smaller hairs called cilia
(say:
sill
-ee-uh) that you can see only with a microscope. The cilia move
back and forth to move the mucus out of the sinuses and back of the
nose. Cilia can also be found lining the air passages, where they
help move mucus out of the lungs.
Sniff, Sniff, Take a Whiff
The nose allows you to make
scents
of what's going on in the world around you. Just as your
eyes
give you information by seeing and your
ears
help you out by hearing, the nose lets you figure out what's
happening by smelling. It does this with help from many parts
hidden deep inside your nasal cavity and head.
Up on the roof of the nasal cavity (the space behind your nose)
is the
olfactory epithelium
(say: al-
fak
-tuh-ree eh-puh-
thee
-lee-um). Olfactory is a fancy word that has to do with smelling.
The olfactory epithelium contains special receptors that are
sensitive to odor molecules that travel through the air.
These receptors are very small - there are at least 10 million
of them in your nose! There are hundreds of different odor
receptors, each with the ability to sense certain odor molecules.
Research has shown that an odor can stimulate several different
kinds of receptors. The brain interprets the combination of
receptors to recognize any one of about 10,000 different
smells.
When the smell receptors are stimulated, signals travel along
the
olfactory nerve
to the
olfactory bulb
. The olfactory bulb is underneath the front of your
brain
just above the nasal cavity. Signals are sent from the olfactory
bulb to other parts of the brain to be interpreted as a smell you
may recognize, like apple pie fresh from the oven. Yum!
Identifying smells is your brain's way of telling you about
your environment. Have you ever smelled your toast burning? In an
instant, your brain interpreted the smell and a problem and you
knew to check on your toast.
You learned to associate a certain smell with burning and now
your brain remembers that smell so you recognize it. Your sense of
smell also can help you keep safe. For example, it can warn you not
to eat something that smells rotten or help you detect smoke before
you see a fire.
Tastes Great!
Most people just think of the
tongue
when they think about taste. But you couldn't taste anything
without some help from the nose! The ability to smell and taste go
together because odors from foods allow us to taste more fully.
Take a bite of food and think about how it tastes. Then pinch
your nose and take another bite. Notice the difference? It's
just another reason to appreciate your knockout of a nose!
Reviewed by:
Mary L. Gavin, MD
Date reviewed: March 2007
Note: All information is for educational purposes only. For specific medical advice,
diagnoses, and treatment, consult your doctor.
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