Ch. 53 Hearing

Question 1

Conduction of sound pathway

Answer 1

tympanic membrane –>ossicles–>chochlea

Question 2

tympanic membrane is attached to the

Answer 2

handle of the malleus

Question 3

3 bones in middle ear:

Answer 3

1. malleus
2. incus
3. stapes (connects to oval window –>inner ear)

Question 4

Attenuation of sound:

Answer 4

after 40-80 seconds of intense sound:
1. stapedius uscle
2. tensor tympani mucles
are contracted with increased rigitidy in ossicles = reduces sound conduction

Question 5

Attenuation of sound benefits (3)

Answer 5

1. protect cohlea from damaging vibration
2. masks low frequency sounds in environments
3. decreases hearing sensitivity to own speech

Question 6

Transmissin of sound through bone

Answer 6

Cochlea implanted in temporal bone. Vibration enter skull = fluid vibrations in chochlea

Question 7

Cochlea is made of:

Answer 7

3 tubes coiled side by side:
1. scala vestibuli
2. scala media
3. scala tympani

Question 8

Sound vibration pathway

Answer 8

vibrations–>scala vestibuli via faceplate at oval window –>faceplate moves inward to push fluid forward and outward to move fluid backward

Question 9

Stiff, short fibers are near

Answer 9

oval window

Question 10

stiff, short fibers beat at

Answer 10

very high frequency

Question 11

long, limber fibers are near

Answer 11

tip of cochlea

Question 12

long, limber fibers vibrate best at

Answer 12

low frequency

Question 13

Fluid wave travels along

Answer 13

basilar membrane

Question 14

fluid wave is strongest at

Answer 14

point of natural resonant frequency

at this point, membrane can vibrate back and forth with ease

Question 15

fluid waves travel ____ initially then get _____

Answer 15

fast initally, then get progressively slower as it goes into chochlea

this allows high frequecy sounds to spread out and separate from one another

Question 16

Pattern of sound wave

Answer 16

A - stapes is all the way in
B - Neutral
C - stapes all the way out

Question 17

______ frequency waves are closest to stapes

Answer 17

higher

Question 18

organ of corti role

Answer 18

generates nerve impulses in response to vibration of basilar membrane

Question 19

Excitation of organ of Corti

Answer 19

1. Stereocillia project upward from hair cells, which are embedded in gel coating of tectorial membrae
2. bending of hairs in one direction depolarizes hair cells, bending in another direction hyperpolarizes them
3. inward and outward movement of basialr fiber causes hairs to shear back and forth in tectorial membrane

Question 20

____% of info comes from inner hair cells of organ of Corti

Answer 20

90-95%

Question 21

what opens or closes mechanically gated ion channels in hair cells?

Answer 21

bending of sterocilia

Question 22

pivoting of steriocillia

Answer 22

opens or closes mechanically gated ion channels

Question 23

What is the electircle potential of hair cells at tips of sterocilia

Answer 23

+80
(creates extra sensitivity)

Question 24

place principle

Answer 24

determining sound frequencies by poition along basilar membrane

Question 25

How does loudness occur

Answer 25

as sound becomes louder, amplitude of vibration in basilar membrane and hair cells increases -->more hair cells become stimulated (spatial summation)

Question 26

decibel unit

Answer 26

10-fold increase in sound energy = 1 decibel logarithm of actual intensities

Question 27

frequency of sound (age comparison)

Answer 27

young: 20-20,000 cycles per second older: 50-8,000 cycles per second young has broader range

Question 28

Nerve fibers from spiral ganglion of Corti enter

Answer 28

dorsal and ventral cochlear nuclei in upper part of medulla-->2nd order neurons to opposite side of brain stem-->terminate in superior olivary nucleus

Question 29

From superior olivary nucleus, auditory pathway

Answer 29

passes upward through lateral lemniscus where some fibers terminate and other -->colliculus where they synase

Question 30

colliculus synapses to

Answer 30

medial geniculate nucleus -->synapse to auditory cortex

Question 31

auditory synapse location

Answer 31

superior gyrus of temporal lobe

Question 32

fibers pass through reticular activating system of brain stem, which:

Answer 32

activates nervous system in response to loud sounds

Question 33

signals form both ears transmitted through the pathway of

Answer 33

both sides of the brain

Question 34

Primary auditory cortex directly excited by

Answer 34

projections from medial geniculate body

Question 35

Secondary association areas are excited secondarily by

Answer 35

impulses from primary auditory cortex

Question 36

Sounds frequency perception

Answer 36

high frequency sounds excite nuerons at one side of tonotopic map, low frequency excite on other side

Question 37

What "sharpens" frequency

Answer 37

lateral inhibition

Question 37

Auditory cortex is important for

Answer 37

discrimination of tonal and sequential sound patterns

Question 38

destruction of both primary auditory cortices would result in

Answer 38

reduced hearing

Question 39

damage to only one primary auditory cortices results in

Answer 39

slightly reduced hearing and affects ability to localize sound

Question 40

Lesions affecting auditory association area:

Answer 40

interfere with ability to interpret meaning of sound

Question 41

How is direction of sound determined

Answer 41

time lag between entry of sound in one ear and entry into opposite ear = difference between intensities of the sounds in two ears

Question 42

What determines if sound is front or behind, above of below?

Answer 42

Pinnae - changes quality of sound based on direction

Question 43

Lateral superior olivary nucleus role

Answer 43

detecting direction from which sound is coming

Question 44

medial superior olivary nucleus role

Answer 44

detects time lag between acoustic signals entering two ears

Question 45

sounds from different areas around the head stimulate

Answer 45

different olivary neurons

Question 46

Deafness can be caused by impairment of(3)

Answer 46

1. Cochlea 2. auditory nerve 3. CNS circuits from ear

Question 47

Main cause of deafness

Answer 47

impairment of physical structures of the ear that conduct sound to cochlea

Question 48

Permanent deafness MOA:

Answer 48

damage to cochlea or auditory nerve

Question 49

Method for measuring hearing

Answer 49

audiometer - emits tone with ranging frequencies