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400 test 2


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52. What is the middle ear reflex?
contraction of the two middle ear muscles usually in reaction to processing of intense acoustic signal, deliberately makes the vibration in the ossicles to not work as well, bilarteral reflex
53. What are two functions of the middle ear reflex?
immobilizes the ossicular chain making a reduction in energy, serve as a brake, built in hearing protection system
Which function is more important from the two of the middle ear reflexes?
This is a physiological brake that halts the system to prevent over vibration
54. What would happen to a sound wave if it struck the opening to the inner ear directly?
there would be poor energy transport.
55. In general terms, what is impedance?
opposition to the flow of energy
Why would an impedance mismatch exist in an auditory system without a middle ear mechanism?
significant loss of energy because air is just hitting something else and doesn’t have a mechanism to vibrate
56. What is the general function of the middle ear (include in this discussion the TM)?
first transducer of energy
57. How does the middle ear system better deliver energy to the inner ear (than if there were no ME)?
because the bones can process the sound and are more sensitive to hearing
What are the specific mechanisms that account for this better energy delivery system?
the tympanic membrane is bigger then the oval window
58. What two sensory/organ systems are housed in the inner ear?
balance and hearing
59. In general terms, what are the functions of the inner ear?
capture frequency of vibration information via the tonotopic organization of the basilar membrane, hearing formulation of neural electronic code via several transductions , third function is balance to send information from the balance organs to the central nervous system
60. What transductions occur in the Inner Ear?
main most critical transducer is the hair cell 1st air  mechanical 2nd mechanical  fluid (stapes/ow) 3rd fluid  mechanical (tectorial mem, cilia)4th mechanical  chemical (synapse of hc to neuron)
61. What is the labyrinth?
generic name for the inner ear
62. What is/where is the bony labyrinth? figure 1.7 pg 17
in the inner ear in the petrous poirtion
63. What are the three sections of the bony labyrinth?
semicircular, cochlea, vestibul
63. In which bony section of the inner ear is the sensory hearing organ housed?
temporal bone, inner ear, in pertrous portion
64. What is the cochlea?
(home of the hearing organ)
65. What is in the bony labyrinth?
Bony shell that contains tissues and fluids
66. What is/where is the membranous labyrinth?
Inside the bony labyrinth the sac that is contained within the bony labyrinth
67. What are the two primary inner ear fluids? How are they different? Where is each located?
Perilymph (high in sodium, na, low in potassium k) and endolymph (high in potassium , k low in sodium)
68. What is the cochlear aqueduct?
28 fig 1.-14, for pari-limph to circulate with cerebral spinal fluid
What is the endolymphatic duct (and sac)?
this goes to a sac under the tissue that is contained inside the membrane it does not share with anything else, endolymph,
69. What is the modiolus and what is its structural significance?
(mo-DIE-o-lus) it forms the structural core of the cochlea, without it you can not have hearing, it is made of bone
70. What is the (BONEY) osseous spiral lamina?
this the end of the modiolus as it is the edge where each organ of corti
71. What are the names of the three channels (also known as scala) in the cochlea?
scala vestibuli (vesti means something to do with the vestibule), scala tympani ( related to the middle ear ends at the round window) scala media (in the center of both channels)
What is the helicotrema?
at the top of the three channels
72. What fluids are in each of the three scala?
perilymph two seronding channels in the scala media is endolmph and organ tissues
73. What in the vestibule opens from the middle ear to the inner ear?
Oval window
74. What is the general structure of the cochlea? Be able to draw and/or label a drawing of a cochlea
osseous spiral lamina, spiral ligament, spiral limbus, tectorial membrane (semi solid material)(covers the organ of corti structures), basilar membrane, Organ of Corti, Reissner’s membrane, stria vascularis (only way things can get in and out of the scala media), scala vestibuli, scala media, scale tympani.
75. What is inside the membranous labyrinth?
Endolymph organ tissues
76. What are the important parts of the Organ of Corti?
rods of Corti (supportive tissue) the tunnel of Corti ( space of fluid) the location for cortilymph( space in the tunnel and in the reticual lamina) , inner hair cells (closer to rods of corti) outer hair cells (closest to the outer wall 12,000 can be attached to the tectorial memberain) tectorial membrane (at the top).
77. Where is/what is perilymph?
secreted by spiral ligament a filtrate of the spinal fluid, found in vestibule and most boney spaces high NA low K (electrically inactive)
78. Where does endolymph come from? Where/how does it go back to?
Stria vascularis in the membranous labyrinth * special blood straight form the blood system* (potential for electrically active) high in K low in NA
79. What is/where is cortilymph?
(fluid in the tunnel of corti we know where it is but not where it comes from (fluid in the tunnel of corti very similar to endolymph ) (high NA low k) ( no electrical activity)
80. What is the chemical composition of each of the three inner ear fluids?
Endolymph is high in patasium low in sodium, perilymph and cortilyph are high in sodum and low in patasium
81. What are the hair cells and what is their function, in general?
They move and set of a chemical reaction sets of a reaction, this is the first place hearing is actually taking place/ afferent (primarily Inner Hair Cell’s or IHC) Outer ear cells are efferent and they are motor control, i.e. they can receive motor control from the nervous system OEC have electromotility i.e. when they are stimulated they move
82. Can you differentiate/describe the differences between outer hair cells and inner hair cells?
shape more afferent nerve endings on the ihc, Inner ear cells are not connected to the tactorial membrane there is a 1-3 ratio between inner and outer hair cells Inner hair cells primary transducers to get information to the brain. Outer hair cells make up only 10% of hearing and very vulnerable to trauma respond to soft sounds (mid-loud intensity is best for HIC) outer hair cells are active inner hair cells are passive.
83. What are stereo-cilia cross links and what is their effect on the HCs?
This makes it so that once one silia moves all the others will move as well
84. What is distinctive about the tectorial membrane and what are its two functions?
Stimulate the outer hair cells by responding to the endolymph wave that has subsequently responded to the parilypmph.
85. Where is the basilar membrane?
Bellow the organ of corti , it vibrates from the endolymph wave that it tonotopically gradual progression / make the basilar membrane respond differently to different frequencies /baisl end responds to high frequencies/ the apical end responds to low frequency responces
86. What happens to the basilar membrane following exposure to sound?
It vibrates at a different rate then the tectorial membrain
87. What are the specific characteristics of the basilar membrane that contribute to the answer in #86?
stiffness width and thickness Basal end is stiff narrow and thin while the apical end is loose wide and thick
88. On the basilar membrane, where is the focus of greatest displacement given a high-frequency stimulus?
Near the basal end
89. On the basilar membrane, where is the focus of greatest displacement given a low-frequency stimulus?
near the apical end
90. What is the importance of the fact that the tectorial membrane and the basilar membrane have different vibrational characteristics?
Create a more powerful wave so that the hair cells get moved
91. What is the origin of the otoacoustic emission?, what does it mean if someone doesn’t have one? What is its major application?
OUTER HAIR CELLS Oto=ear acoustic=sound emission= out of, round window is pushed and this creates a sound in the middle ear, Then the hair cells are not working and the person in turn can’t hear. To tell whether or not the entire outer hair cell system is working or not. To test on very young children/infants

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