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The Ear – Hearing and Equilibrium
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EarsYour ears are in charge of:
• collecng sounds• processing them • sending sound signals to your brain• keeping your balance.
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The ear is divided into three areas
• Outer (external) ear• Middle ear• Inner ear
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The Outer (External) EarThe outer ear is called the pinna or auricle.
• This is the part of the ear that people can see.
• The main job of the outer ear is to collect sounds, whether they're your friend's whispers or a barking dog.
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The Outer Ear• The outer ear also includes the ear canal,
where wax is produced.
• Earwax contains chemicals that fight off
infecons that could hurt the skin inside the ear canal. It also collects dirt to help keep the ear canal clean.
• Don’t go poking around in your ears, not
even with coon swabs! As you probably know, there's only one thing that's safe to put in your ear. Your elbow, of course. ☺
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The Middle Ear or Tympanic Cavity• Aer sound waves enter the outer ear, they
travel through the ear canal and make their way to the middle ear.
• The middle ear's main job is to take those sound waves and turn them into vibraons that are delivered to the inner ear.
• To do this, it needs the eardrum, which is a thin piece of skin stretched ght like a drum.
• The eardrum separates the outer ear from the middle ear.
• When sound waves reach the eardrum, they cause the eardrum to vibrate. When the eardrum vibrates, it moves the ossicles (the niest bones in your body) ‐ from the hammer to the anvil and then to the srrup. These bones help sound move along on its journey into the inner ear.
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The Middle Ear• The opening from the auditory
canal is covered by the tympanic membrane (Ear drum)
• The auditory tube connecng the middle ear with the throat
• Allows for equalizing pressure during yawning or swallowing
• This tube is otherwise collapsed
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Three bones span the cavity (the smallest bones in our bodies!!)• Malleus (hammer)• Incus (anvil)• Stapes (stirrip)
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The Inner Ear• Sound comes into the inner ear as vibraons and
enters the cochlea (say: ko‐klee‐uh), a small, curled tube in the inner ear.
• The cochlea is filled with liquid, which is set into moon, like a wave, when the ossicles vibrate.
• The cochlea is also lined with ny cells covered in ny hairs that are so small you would need a microscope to see them. They may be small, but they're awfully important.
• When sound reaches the cochlea, the vibraons (sound) cause the hairs on the cells to move, creang nerve signals that the brain understands as sound.
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Balance/ Equilibrium• Your ears keep you balanced.• In the inner ear, there are three small loops above the cochlea
called semicircular canals. Like the cochlea, they are also filled with liquid and have thousands of microscopic hairs.
• When you move your head, the liquid in the semicircular canals moves, too. The liquid moves the ny hairs, which send a nerve message to your brain about the posion of your head. In less than a second, your brain sends messages to the muscles so that you keep your balance.
• Somemes the liquid in your semicircular canals keeps moving aer you've stopped moving. (dizziness)
• Once the fluid in the semicircular canals stops moving, your brain gets the right message and you regain your balance.
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Receptor cells are in two structures:VesbuleSemicircular canals
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EquilibriumStatic equilibrium– sense of gravity at rest. Ability to stay still in one place.
Dynamic equilibrium– angular and rotary head movements. Keeping a sense of where you are at all times
Think of a snowboarder doing a flip and being able to land on their feet.
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Interesng Fact…
• Sight also plays a roll in keeping your balance. • Everyone try standing up right now. Keep your eyes open
and try to balance on one leg. • Now let’s try keeping our balance on one leg with our eyes
closed. Even trickier right?
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http://www.brainpop.com/health/senses/hearing/preview.weml
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