6. 7 Ear Structure and Function

Question 1

CN8: sensory neurons in ______ ganglion for balance or ________ ganglion for hearing

Answer 1

vestibular, auditory

Question 2

axons from CN8 synapse in the brainstem at the _______ or _______ nuclei

Answer 2

vestibular, cochlear

Question 3

peripheral components of the auditory system include the _______, _______, and ______ ear, providing info about sound in the environment

Answer 3

external, middle, inner

Question 4

______ cells are the sensory transducers of the auditory system

Answer 4

hair

Question 5

afferent info from 8th nerve synapses on _______ nuclei in the brainstem in the auditory system

Answer 5

cochlear

Question 6

peripheral components of the vestibular system are the _______ ear

Answer 6

inner

Question 7

vestibular system provides info about _____ and _______, and hair cells are the sensory transducers

Answer 7

motion and gravity

Question 8

in the vestibular system, afferent info from the 8th nerve synapses on __________ nuclei in the brainstem

Answer 8

vestibular

Question 9

info from the vestibular system does not reach the _______, but interacts with the motor system

Answer 9

cortex

Question 10

auditory and vestibular hair cells transduce energy via movement of their ___________

Answer 10

stereocilia

Question 11

deflection of hair bundle towards its tall side causes ________, whereas deflection toward its short side causes __________

Answer 11

depolarization (excitation) , hyperpolarization (inhibition)

Question 12

vestibular hair cells are located in the __________ and ________

Answer 12

macular organs (saccule, utricle), semicircular canals (crist ampullaris)

Question 13

the vestibular hair cells in the macular organs (saccule, utricle) detect _______

Answer 13

linear acceleration (gravity)

Question 14

the vestibular hair cells in the semicircular canals (crista ampullaris) detect ______________

Answer 14

rotational acceleration

Question 15

embedded in a glycoprotein matrix and sit on top of hair cell stereocilia?

Answer 15

otoliths

Question 16

otoliths shift with ________ and bend stereocilia, changing neurotransmitter release by hair cells

Answer 16

gravity

Question 17

hair cells in ampullae sit on ridge of tissue called __________

Answer 17

crista ampullaris

Question 18

stereocilia are embedded in the _________, a tall glycoprotein matrix mass

Answer 18

cupula

Question 19

the cupula is deflected by fluid flowing through the canal when ___________

Answer 19

the head turns

Question 20

adequate stimulus for kinetic labyrinth (semicircular canals)?

Answer 20

dynamic stimuli (rotational forces) and head acceleratin/deceleration

Question 21

adequate stimulus for static labyrinth (otolith organs, utricle saccule)?

Answer 21

static stimuli, maintained head position (tilit), translational forces and horizontal displacement

Question 22

ossicular chain and the size difference between the tympanic membrane and oval window prevents loss of pressure at oval window

Answer 22

impedence matching

Question 23

eustachian tube connects the middle ear and nasopharynx, allowing for?

Answer 23

pressure equalization

Question 24

what two muscles can change the stiffness of the tympanic membrane or dampen the movement of the stapes, increasing dynamic range of ear and protecting cochlear hair cells from loud sounds?

Answer 24

tensor tympani and stapedius

Question 25

shearing force against stereocilia with ____________ movement; change in hair cell membrane potential causes release of neurotransmitter at the base

Answer 25

basilar membrane movement

Question 26

endolymph has ______ mV endolymphatic potential, and is high in the ion _______

Answer 26

+80, potassium

Question 27

perilymph has ______ mV hair cell membrane potential, and is high in the ion ______

Answer 27

-40, sodium

Question 28

the 120 mV membrane potential drives ______ ions into the hair cells

Answer 28

potassium

Question 29

the _________ secretes K+ ions

Answer 29

stria vascularis (lining of scala media)

Question 30

the __________ separates endolymph from perilymph

Answer 30

reticular lamina

Question 31

sound waves enter external auditory canal - tympanic membrane vibrates - _______ vibrate and increase force - _______ window vibrates and sets up motion in perilymph of scala vestibuli - vestibular membrane transfers vibration to scala media - ______ membrane vibrates - hair cells move relative to tectorial membrane - ________ deflect toward long side - channels open and K+ enters through stereocilia tips - ______ membrane depolarizes - voltage gated ______ channels open and enters hair cell - neurotransmitter released - afferent nerves respond with action potential headed for brainstem

Answer 31

``` ossicles oval basilar stereocilia hair cell calcium ```

Question 32

movement of basilar membrane is not uniform along its length- displacement in a given region depends on __________

Answer 32

sound frequency

Question 33

the apical end of the basilar membrane is most sensitive to _____ frequency sounds, and the base is more sensitive to _______ frequency sounds

Answer 33

low, high

Question 34

in the cochlea, inner hair cells ______ and outer hair cells modify ____________

Answer 34

transduce, basilar membrane movement

Question 35

outer hair cells can amplify the transduction of _______ sounds and attenuate the transduction of ______ sounds

Answer 35

low level(faint), and high level (loud)

Question 36

outer hair cells receive innervation from efferent fibers that originate in the _________ nucleus in the pons

Answer 36

superior olivary

Question 37

the 8th nerve and cochlear nucleus receive _________ input from the ipsilateral ear

Answer 37

monaural

Question 38

all other nuclei above the level of the cochlear nucleus receive input from __________

Answer 38

both ears

Question 39

auditory cortex is located on the lower bank of the _______ sulcus

Answer 39

lateral