PHYS phys of the auditory and vestibular systems

Question 1

Endolymph is similar to

bathes what end of the hair cell

Answer 1

ICF

bathes apical end

Question 2

Perilymph is similar to

bathes what end of the hair cell

Answer 2

ECF

bathes basal end

Question 3

where is maximal motion for high frequencies located in the cochlea

Answer 3

at base

Question 4

where is maximal motion for low frequencies located in the cochlea

Answer 4

more apically

Question 5

what type of receptors are hair cells

Answer 5

mechanoreceptors

Question 6

electrochemical driving results from what two factors

Answer 6

large endolymphatic potential (high [K] in endolymph)

large electrical gradient (scala media has high + charge ~+80mV)

Question 7

deflection of stereocilia toward kinocilium

Answer 7

depolarization of hair cells

Question 8

deflection of stereocilia away from kinocilium

Answer 8

hyperpolarization of hair cells

Question 9

what opens the channels on hair cells

Answer 9

stereocilia are linked by “chains”
depending on direction of deflection, Ca/K channels can be opened

K open –> depol. –> Ca channels open

Question 10

what are the ion channels on the stereocilia
what ion do they transport
what is their purpose

Answer 10

TRPA1
K
allow K influx to depol cell when stereocilia deflect toward kinocilium

Question 11

what do hair cells release in response to influx of Ca

Answer 11

Glutamate

Question 12

what maintains the electrochemical properties of the endolymph

Answer 12

stria vascularis

Question 13

how many inner hair cells and how many outer hair cells are there on the basilar membrane

Answer 13

one row of inner hair cells

three rows of outer hair cells

Question 14

f(x) of inner hair cells

Answer 14

primary source of auditory information

Question 15

what makes the outer hair cells contractile

Answer 15

prestin

Question 16

f(x) of outer hair cells

Answer 16

acts as an amplifier

Question 17

what type of afferent neuron takes information from the inner hair cell to the spiral ganglion

Answer 17

type 1 neuron (95%)

Question 18

what type of afferent neuron takes information fom the outer hair cell to the spiral ganglion

Answer 18

type 2 neuron

Question 19

where do hair cells receive efferent innervation from

Answer 19

superior olivary complex

Question 20

what is the primary nuclei of the superior olivary complex

Answer 20

medial superior olivary nucleus (MSO)

lateral superior olivary nucleus (LSO)

Question 21

what is the first site in the brainstem where information from both ears converge

Answer 21

superior olivary complex

essential to accurately localize sound

Question 22

f(x) of MSO

Answer 22

generate a map of interaural time differences

helps the localization of sound

Question 23

under what conditions does the MSO respond the strongest

Answer 23

when 2 inputs arrive simultaneously

Question 24

f(x) of LSO

Answer 24

generate a map of interaural intensity differences
helps localize source of sound

site of sound localization excites ipsilat. side LSO and receives inhib. from contralat. side, but excite>inhib.

Question 25

f(x) of primary auditory cortex (A1)

Answer 25

essential in conscious perception of sound | beginning to interpret of sound

Question 26

in the primary auditory cortex, which end (rostral/caudal) corresponds with high frequencies/low frequencies

Answer 26

more rostral end corresponds to apex of cochlea (low frequency) more caudal end corresponds to base of cochlea (higher frequency)

Question 27

secondary auditory complex f(x)

Answer 27

thought to respond to more complex sounds (music), identifying (naming) a sound, and speech

Question 28

``` VCN f(x) (pierce) ```

Answer 28

nature of sound (high, low)

Question 29

``` DCN f(x) (pierce) ```

Answer 29

location of sound

Question 30

Inferior colliculus (IC) f(x)

Answer 30

suppresses information related to echoes | creates spatial map of sound

Question 31

efferent input to the auditory system (3)

Answer 31

``` olivocochlear efferents (OC) middle ear muscle motorneurons autonomic innervation of the inner ear ```

Question 32

OC efferents origination what do they innervate

Answer 32

originate from superior olivary complex medial OC innervate outer hair cells lateral OC innervate inner hair cells

Question 33

OC efferents f(x)

Answer 33

shifts responses to higher sound levels? decrease adaptation reduce response to noise may protect hair cells from damage to intense sounds

Question 34

middle ear efferents | f(x)

Answer 34

tensor tympani to malleus (CN V) stapedius to the stapes (CN VII) bilat. response to high sound levels contractions decrease transmission of sound prevent damage may preven low frequency masking ( improve speecch discrimination)

Question 35

two types of otoacoustic emissions

Answer 35

spontaneous - pure tones; probably generated from movement of outer hair cells evoked - used for testing hearing loss (n/a if damage present)

Question 36

Sensorineural hearing loss is caused by

Answer 36

damage to hair cells, nerve fibers or both | base is more susceptible to damage than apical end

Question 37

effects of injury to outer hair cells

Answer 37

decrease in sensitivity (higher threshold) and broader tuning

Question 38

effects of injury to inner hair cells

Answer 38

cuts off auditory input to CNS

Question 39

what detects rotational acceleration

Answer 39

semicircular canals anterior - falling forwards posterior - falling backwards horizontal - horizontal rotations (spin?)

Question 40

what detects forward and backward linear acceleration

Answer 40

utricle

Question 41

what detects up and down linear acceleration

Answer 41

saccule

Question 42

vestibulo-optic reflexes horizontal rotation falling forward falling backward which m. involved in each

Answer 42

horizontal - medial rectus on same side of rotation activated, lateral rectus inhibited (opposite for contralat. eye) falling forward - superior rectus activated, inferior rectus inhibited falling backward - superior oblique activated, inferior oblique inhibited