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SPLH 620 Exam 2
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Exam of 9 pages for the course NR 509 Final Exam at NR 509 Final Exam (SPLH 620 Exam 2)
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SPLH 620 Exam 2What nerve is is involved in hearing and balance? - ANS-CN VIII (Vestibulocochlear!)
What does vestibular mean? - ANS-Position and movement of head
What is the brief anatomy of the ear (hearing & balance system)? - ANS-1. Outer Ear
(pinna, ear canal)
2. Middle Ear (tympanic membrance, ossicles (malleus, incus, stapes))
3. Inner Ear (Cochlea, Vestibular System)
What are the parts of the Middle Ear? What is the inner ear filled with? - ANS-1.
Tympanic Membrane
2. AIR FILLED!
3. Ossicles (malleus, incus, stapes)
4. Oval Window
Inner ear: FLUID filled!
What are the functions of the Middle and Inner Ear? - ANS-M: Amplification of signal,
transforms signal (acoustic to mechanical)
I: Transforms signal (mechanical to chemoelectric), represent sound frequencies
What are the layers in the Cochlea? - ANS-Top: Scala Vestibuli (perilymph fluid)
Middle: Cochlear Duct (endolymph fluid)
Bottom: Scala Tympani (perilymph fluid)
How many times is the Cochlea coiled? - ANS-2.5 turns
Where is the Organ of Corti located and what is it? - ANS-Located in the Scala Media
It's a sensory organ for the hearing system, it's composed of hair cells
Where does the Organ of Corti rest? - ANS-It rests on the basilar membrane. It's
composed of hair cells. Inner Hair cells (3500), Outer Hair cells (15000).
What are the inner hair cells and outer hair cells responsible for? - ANS-I: 90 - 95% of
all cochlear nerve fibers receives input from the IHC (sensory receptors)
O: amplify signal
, How is AP generated in the cochlea? - ANS-Wave energy from the cochlea causes the
BM to vibrate, bending HC which generates AP
What is the structure located directly above the Hair Cells? - ANS-The Tectorial
Membrane
How does the HC get excited or inhibited? - ANS-When the HC bend towards the
highest cilia then the HC depolarizes which leads to an increase in AP firing.
However, when the HC bend away from the tallest cilia then the HC is inhibited and
there's a decrease in AP firing
What characteristics are encoded by the HC's? - ANS-Duration and Intensity
What occurs during hyperpolarization and depolarization of the HC's? - ANS-H: Ion
channels are closed, no longer inward movement of K+, decrease in freq. of AP's in
Aud. nerve.
D: Ion channels open, K+ flows into HC, depolarization increases the membrane
potential, CA+ ions open, triggers exocyctosis (releasing of vescles) which bind to Aud.
nerve which leads to an increase in frequency of AP's
How is the tonotopic map of the cochlea laid out? - ANS-High frequencies at the base
Low frequencies at the apex
What are the structures involved in the Auditory Pathway? - ANS-1. Sound enters ear
and stimulates the CN VIII
2. Information is passed through the 1) Superior Olive 2) Lateral Lemniscus 3) Inferior
Colliculus and 4) Thalamus (Medial Geniculate Nucleus)
3. Auditory Cortex receives Thalamus input and processes signal
How is spatial hearing computed by? - ANS-1. Interaural level differences
2. Interaural time differences
They are enabled by bilateral design
The hair cells project to where? - ANS-Dorsal and Ventral cochlear nuclei
What is the difference between the Dorsal cochlear nucleus and the Ventral cochlear
nucleus? Along with that what is the auditory pathway? - ANS-D: most axons cross over
to inferior colliculus
V: axons synapse on the ipsilateral and contralateral Superior Olivary Nucleus
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