Transcript Hair Cells - Ms. Engel @ South

THE AUDITORY
SENSE
A PRESENTATION BY:
Danielle Anderson / Emily Breuer
Maxwell Dietrich / Tim Jiang / Linda La
and Cary Potochnik
Outer Ear
Pinna
• Funnels sound waves into the
ear canal
• The external flap of skin and
cartilage
Ear Canal
• The tube through which
sound travels to the eardrum
Tympanic Membrane
• A thin membrane at the end
of the ear canal
• Also known as the eardrum
Main Function - Funnel
for receiving sounds waves and
transporting them inward
http://www.medicalook.com/systems_images/Outer_E
ar.jpg
Middle Ear
• Air filled cavity behind the
tympanic membrane
• Osicles-transmit sound energy
from tympanic membrane to
cochlea
Malleus-attached
to
eardrum
Incus
Stapes-attached to
membrane
that covers the inside of the oval
window
• Eustachian tube-opens and closes
to maintain constant pressure
with environment
• Main function - To increase the
amount of pressure that sounds
waves exert upon the inner ear so
that transduction can occur
http://wikis.lib.ncsu.edu/images/8/85/Middle_e
ar.gif
Inner Ear
Oval Window
• Beginning of inner ear
Cochlea
• Contains fluid-filled outer
duct
o 
duct begins at oval
window, runs to tip of
cochlea, ends at
another membrane
called Round Window
Inner Duct
• Sandwiched between
outgoing and incoming
portions of outer duct
• fluid filled tube
http://images.tutorvista.com/content/nervouscoordination/human-ear-internal-structure.jpeg
Inner Ear Cont.
Basilar Membrane
• Forms the floor of Inner Duct
• Where Hair Cells are located
Hair Cells
• Receptor cells for hearing
• Three outer rows and one inner
row along length of Basilar
Membrane
• Cilia protrude from hair cell and
abut against Tectorial Membrane
• At other end from its hairs, each
hair cell forms synapses with
several auditory neurons
Cilia
• Tiny hairs protruding from each
hair cell
o move in response to
vibrations from Tympanic
Membrane
http://3.bp.blogspot.com/_M2b4HfNGay4/RouytN4R
xjI/AAAAAAAAAWI/lntByw74zk8/s320/the_ear_diagr
am.gif
Basics on waves
Volume = Amplitude
Pitch = Frequency
http://dbooth.net/mhs/chem/wave-transverse02.gif
cheriestihler.com/SB/SquishyScience/p-1-3_ani-ear.gifClick to add
content
Transduction: Turning
vibrations into sound
Transduction:
The Beginning
Before the phases of transduction, the incoming vibrations are
prepared for translation into sound
• The Pinna collects sound
• The eardrum (tympanic membrane) captures the sound
• The malleus, incus, and stapes bones receive vibrations
and carry them on to the cochlea
• The stapes sends vibrations to the oval window, which
increases the pressure (causing amplification) due to the
oval window's small surface area.
Transduction:
The Cochlea
Vibrations in the ossicles (malleus, incus, stapes) and the oval
window cause changes in the cochlea
• The cochlear fluid and the basilar membrane begin to
vibrate according to the input frequencies
• Hair cells of the basilar membrane bend against the
tectorial membrane.
http://universe-review.ca/I10-85-cochlea2.jpg
Transduction:
The Hair Cells
Hair cells strike the tectorial membrane and experience
membrane changes, making them more likely to uptake ions
and cause an action potential
• Lower pitches travel further down the cochlea before the
wave peaks and cause an action potential
• The combination of action potentials determines sound
quality
• Aural information travels to the higher parts of the brain,
particularly the temporal lobe, for interpretation
Sensorial Hearing Loss
• the bones, eardrum, and
membranes of the ear are
functional, but the hair cells of
the cochlea are damaged
• electrical impulses cannot
reach the nerve fibers-->
cannot carry information to
brain
• can be caused by genetic
factors, injury, illness, natural
http://www.clivir.com/pictures/hearing_loss/hearin
aging, or ototoxic drugs
g_types.jpg
Cochlear Implant
•
•
•
•
transforms sounds into electrical impulses
sends impulses through wires implanted in cochlea
stimulate auditory neuron terminals
it does not make sounds louder, but instead it directly
stimulates the nerve fibers in the cochlea to help the
person sense sound
http://www.terptopics.com/
images/ALD%20Cochlear%20Implant
%20(External%20Components).jpg
http://kidshealth.org/parent/general/eyes/
images_80941/P_cochlear-noConsole.jpg
Synesthesia
• Greek for “to perceive together"
• "Colored hearing" (chromesthesia) is most common
• Results from strong connections between sensory parts of
the brain
• Affects about 5% of the population
• Consistent with an individual, but varies by person
• Dr. Ramachandran on Synesthesia
• Part 2
Chromesthesia
• Chromesthesia is a condition
where one 'hears colors.' For
individuals with
chromesthesia, certain sounds
may trigger visualizations of
colors and shapes.
Phantom Words
• An auditory illusion that
occurs when the brain
tries to process unfamiliar
words
• The brain tries to
construct phrases because
it processes meaningless
words
• Often times the words a
person thinks she or he hears
are related to what is on the
person's mind
Example 1
Example 2
Example 3
Bibliography
Bogart, Cathy J. "Synesthesia ." Magill's Encyclopedia of Social
Science: Psychology. 2nd ed. Pasadena, CA: Salem Press, Inc., 2003.
1599-1602. Print.
Gray, Peter. "Smell, Taste, Pain, Hearing, and Psychophysics".
Psychology. 5th ed. New York, NY: Worth Publishers, 2007. 225-261.
Print.
Magill, Frank N, ed. “The Auditory System.” Psychology Basics. 4th ed.
Pasadena, CA: Salem Press, Inc., 1998. 82-87. Print.
"Heard and misunderstood: don't believe your ears, says Diana
Deutsch." Psychology Today Jan.-Feb. 2004: 83. General OneFile.
Web. 23 Oct. 2011.
Bibliography(Cont.)
Powell, Devin. "What it means to 'feel the noise': hearing,
touch appear to be physically linked in the brain." Science
News 18 June 2011: 11. General OneFile. Web. 23 Oct. 2011.
Ryerson, Nancy. "Technicolor type: shades of synesthesia are
built into our brains." Psychology Today May-June 2011: 20.
General OneFile. Web. 23 Oct. 2011.
Zeman, A. "Synesthesia--a union of the senses." Journal of
Neurology, Neurosurgery and Psychiatry 75.1 (2004): 173+.
General OneFile. Web. 23 Oct. 2011.
"Top 10 Incredible Sound Illusions." Top 10 Lists - Listverse.
Web. 23 Oct. 2011. <http://listverse.com/2008/02/29/top-10incredible-sound-illusions/>.