Ch 10.2: Ears & Hearing

Question 1

Frequency is measured in ___ while intensity and loudness are measured in ___

Answer 1

Hz; db

Question 2

Human range of frequency

Answer 2

20-20,000Hz

Question 3

Optimal range for loudness in humans

Answer 3

0-80db

Question 4

Path of sound in outer ear

Answer 4

funneled by pinna —> external acoustic meatus —> tympanic membrane (eardrum)

Question 5

Middle ear

Answer 5

air-filled cavity between tympanic membrane and the cochlea

Question 6

Path of sound in middle ear

Answer 6

eardrum —> malleus —> incus —> stapes —> oval window —> cochlea

Question 7

What does the stapedius muscle do?

Answer 7

dampens the stapes if sound is too intense

Question 8

Chambers of the cochlea

Answer 8

1) upper chamber (scala vestibuli, portion of upper labyrinth)
2) lower bony chamber (scala tympani)
3) portion of scala media (cochlear duct)
4) helicotrema (small canal between scala vestibuli and scala tympani)

Question 9

What fills cochlear chambers?

Answer 9

perilymph

Question 10

What fills the cochlear duct?

Answer 10

endolymph

Question 11

After reaching the oval window, vibrations displace _____ in ______

Answer 11

perilymph; scala vestibuli

Question 12

Where are low frequency sounds received in the cochlea?

Answer 12

toward the apex

Question 13

Sensory hair cells are located in the _____ projecting into _______ of the cochlear duct

Answer 13

basilar membrane, endolymph

Question 14

Inner hair cells

Answer 14

3500 form one row the entire length of the basilar membrane

Question 15

Inner hair cells are innervated by

Answer 15

10-20 sensory neurons of cranial nerve VIII that relay sound

Question 16

Outer hair cells

Answer 16

11,500 in rows with 3 rows per turn

Question 17

Outer hair cells are innervated by ________ that make them shorten when _________ and lengthen when ____________

Answer 17

depolarized; hyperpolarized

Question 18

Hairs in the organ of corti are made of ____ that are large _____ arranged in _____

Answer 18

stereocilia; microvilli; bundles

Question 19

Stereocilia are interconnected and ___ in size with each bundle

Answer 19

increase stepwise

Question 20

Where do stereocilia embed in the organ of corti?

Answer 20

in a gelatinous tectorial membrane

Question 21

Components of spiral organ

Answer 21

basilar membrane, inner hair cells, sensory fibers, tectorial membrane

Question 22

Vibration of tectorial membrane bends stereocilia, results in the opening of _____ into the ________

Answer 22

K+ channels; endolymph

Question 23

the ____ the amount of basilar membrane displaced/bending of stereocilia, the more _____ is released, producing a ____ receptor potential

Answer 23

greater; glutamate; greater

Question 24

In place theory, which hair cells are stimulated more often?

Answer 24

hair cells closer to where vibrations are displaced in the scala media

Question 25

sound localization is based on

Answer 25

interaural intensity and time differences

Question 26

What is the first stop of the neural pathway of sound transduction?

Answer 26

vestibulocochlear nerve

Question 27

Conduction deafness

Answer 27

sound waves not conducted from outer to inner ear

Question 28

What may cause conduction deafness?

Answer 28

earwax buildup, fluid in middle ear, damage to eardrum, bone overgrowth in middle ear

Question 29

What frequencies does conduction deafness impair?

Answer 29

all

Question 30

How can conduction deafness be helped?

Answer 30

earing aides

Question 31

Sensorineural/perceptive deafness

Answer 31

nerve impulses are not conducted from the cochlea to the auditory cortex

Question 32

What causes sensorineural/perc deafness?

Answer 32

damaged hair cells from loud noises

Question 33

What frequencies are affected by s/p deafness?

Answer 33

only particular frequencies where haircells are damaged

Question 34

How can S/P deafness be helped?

Answer 34

cochlear implants

Question 35

Presbycusis

Answer 35

age-related hearing impairment

Question 36

After scala vestibuli is displaced, sound travels across the _____ and down into the ____

Answer 36

vestibular membrane; cochlear duct

Question 37

At the cochlear duct, sound passes through ____ to reach the _______ membrane

Answer 37

endolymph; basilar

Question 38

Passing through the basilar membrane, sound reaches ______ of the scala ________ and travels out of the cochlea via the ______

Answer 38

perilymph; tympani; round window

Question 39

How does place theory explain nerve transduction of sound?

Answer 39

the physical differentiation of hair cell stimulation acts as a neural code for pitch discrimination

Question 40

According to place theory, how can similar pitches be differentiated?

Answer 40

via the magnification effect produced by outer hair cells

Question 41

What parts of the brainstem are stimulated by the vestibulocochlear cranial nerve VIII?

Answer 41

the medulla oblongata, pons and the inferior colliculi

Question 42

Where in the thalamus do nerve impulses from sound pass?

Answer 42

through the medial geniculate body

Question 43

Where in the cortex do auditory signals go for interpretation?

Answer 43

to the auditory cortex of the temporal lobe

Question 44

How does the auditory cortex break down sound interpretation?

Answer 44

it is tonotropic, in that different areas of the auditory cortex process different sound frequencies

Question 45

What happens once K+ in released into endolymph from stereocilia stimulation?

Answer 45

depolarization and release of glutamate NT at the synapse with sensory neurons

Question 46

When the AP completes, K+ of the endolymph returns to ______ at the base of _____cilia

Answer 46

perilymph; stereo