Download and the outer hair cells

EAR
 EAR
IS THE SENSE ORGAN WHICH HELPS US IN
HEARING IT ALSO HELPS US IN MAINTAIN THE
BALANCE OR EQUILIBRIUMOF OUR BODY
 COCHLEA
IS THE MAIN PARTS WHICH HELPS
IN HEARING
PARTS OF THE EAR
EXTERNAL EAR
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EXTERNAL EAR CONSISTS OF PINNA AUDITORY
CANAL AND EAR DRUM .PINNA HELPS TO DIRECT
THE SOUND WAVESINTO THE AUDITOR CANAL.
CERUMINOUS
GLAND IS SPECIAL GLAND WHICH ARE FOUND IN
THE WALLS OF THE AUDITOURY CANALWHICH IS
THE CONSTITUTION OF PINNA. THE WAX
PRODUSED BY THESE GLANDS AND THE HAIR IN
THE AUDITORY CANAL TOGETHER PROTECT THE
EAR FROM SMALL INSECTS, GERMS AND DUST.IT
HELPS IN MAINTAIN THE TEMPERATURE AND
DAMPNESS OF THE AUDITORY CANAL ENDS IN
THE EAR DRUM.
MIDDLE EAR
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MIDDLE EAR IS AN AIR FILLED CAVITY WHICH LIES
JUST BEYOND THE EAR DRUM.
MIDDLE EAR CONSIST OF 3 SMALL BONES
1)HAMER SHAPED BONE ATTACHED TO EAR DRUM
IS CALLED MALLEUS
2)ANVIL SHAPED BONE IS CALLED INCUS
3)THIRD BONE IS THE STAPES IT IS THE SMALLEST
BONE IN THE HUMAN BODY.
AN AIR PASSEGE CALLED EUSTACHIAN TUBE HELPS TO CONNECT
THE MIDDLE EAR WITH PHARENIX.EUSTACHIAN TUBE HELPS TO
MAINTAIN AIR PREEASURE BALANCE OF EITHER SIDE OF EAR
DRUM
INNER EAR
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INNER EAR IS SITUATED IN THE BONY
CAVITY IT CONTIN 2 LABRINTH
1)BONY LABRINTH
2)MEMBERANEOUS LABRINTH
INNER EAR IS MADE OF 2 PARTS WESTIBULAR
APPARETUS AND CHOCLEA IT INCLUDES 3
SEMICIRCULARCANALS.
EACH SEMICIRCULAR CANAL THERE IS A
SWELLING CALLED AMPULLA CONTAIN RESIPTORS
CALLED CRISTATE UTRICLE AND SACULES
CONTAIN RESIPTORS AND MACULAE
CAUSES OF DEAFNESS
INFECTION IN THE EUSTACHIAN TUBE WILL SPREAD
TO MIDDLE EAR TOO
 EAR DRUM MAY BECOME DAMAGED BY AN INFECTION
IN THE AUDITORY CANAL
 LEADING TO DEAFNESS IS EXCESS NIICE STRONG
BLOW ON THE CHEAK
 POINTED OBJECT ENTERING THE EAR
 ATTACK OF THE INSECT LEAD DEAFNESSDEFECT IN
THE ,CHOCLEA,AUDITORY CANAL,BRIANARE ALSO
REASON FOR DEAFNES
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This is an animation of a bird's hearing
system. It is very similar to the human
equivalent, except that the cochlea (on the
right) doesn't spiral in so many times. The
bird cochlea has 0.75 turns; The human
cochlea has 2.5 turns
On the far left is the eardrum. This vibrates in response to
incoming sound. From the eardrum, the vibration passes along the
three bones, the hammer (which is connected to the eardrum), the
anvil and the stirrup. It is not too easy to see in this diagram, but
the bones are similar in shape to the items after which they are
named.
 The last of the bones, the stirrup, moves with about 20 times the
force of the hammer due to the lever principal. So these bones
serve as a form of amplification.
 From the stirrup, the vibration passes through the oval window
into the cochlea, where it causes a liquid called the cochlear fluid,
located in the upper and lower galleries of the cochlea (see later
diagram) to vibrate. In between the two galleries, is the organ of
corti, which spirals along the length of the cochlea (shown as a
black and yellow line in the first drawing).
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It is inside the organ of corti that we find the
hair cells.
These are nothing to do with hairs on your head.
They are the receptors involved in changing the
sound pressure wave into a nerve signal. Hair
cells get their name from the hair like projections
at their top which are known as 'cilia'. There
are 50 to 100 'hairs' on each hair cell.
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Here is a cutaway diagram of the human
cochlea seen from a different perspective. It
is in all about 1.5 cm in diameter. You will
see that the spiralling tunnel has a bony
shelf that divides it into two galleries; the
upper and the lower. The organ of corti runs
along the edge of this bony shelf.
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different positions along the length of the
organ of corti inside thecochlea respond to
different frequencies.
The organ of corti, which runs the whole length of the cochlea,
contains two subtly different types of hair cells; the inner hair cells
(IHCs) (green in the diagram)and the outer hair cells
(OHCs) (blue).
Current theory (Which is not 100% perfect, but is 'state of the
art') tells us that the IHCs are in the main responsible for the
actual 'hearing' of sounds, while the OHCs, which are really tiny
muscles, are responsible for 'fine tuning' the frequency response sharpening up that narrow notch mentioned earlier.
 This diagram shows only a small section of the structure. It
actually runs the whole length of the coiled cochlea. The hairs, or
cilia ,on the inner hair cells which detect the sound are shown in
green. The hairs on the outer hair cells are shown in blue. The
cells themselves are underneath. The dark circle in the middle of
each cell is its nucleus. Note that there are three rows of outer
hair cells and just one row of inner hair cells
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TO PROTECT EAR
AVOID SWIMMING IN CONTAMINATED
WATER.
 DONOT INSERT SHARP OBIECT INTO THE
EAR IT CAN CAUSE INJURY
 AVOID HIGH FREQUENCY SOUND
 NEVER STRIKE ANY ONE ON THE CHEAK
EVEN FOR FUN
 AVOID INFECTION IN THE INTERNAL EAR
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COCHLEA
Prepared by
Jithin krishna.R (X A)
 Arjun Manoj (X A)
 Sooraj Dev.J.R (X A)
 Mohammed Suhail (X D)
 S.M.V.H.S.S
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