Hearing

Question 1

What are the parts of the outer ear

Answer 1

pinna, external auditory meatus (aka ear canal)

Question 2

What are the parts of the middle ear

Answer 2

tympanic membrane, ossicles, eustachian tube

Question 3

What is the order of the ossicles

Answer 3

malleus, incus, stapes

Question 4

What are the parts of the inner ear

Answer 4

vestibular and cochlea

Question 5

What are the 3 sections of the cochlea

Answer 5

scala vestibuli, scala media (cochlear duct), scala tympani

Question 6

Sound waves are characterized by…

Answer 6

frequency and intensity (pitch and loudness)

Question 7

The oval window and the round window…

Answer 7

separate the fluid-filled inner ear from the air-filled middle ear

Question 8

the steps of sound transmission

Answer 8

the ear cannal collects the sound waves, the sound waves vibrate the tympanic membrane which moves the ossicles, the stapes foot plate moves in and out of the oval window sending the vibrations to the cochlea, when sound energy is transferred to the cochlea the basilar membrane vibrates up and down causing the outer hair cell sterocilia to shear on the tecorial membrane above, this shearing action causes the stereocilia to bend which opens ion gates and leads to chemical changes (nerve impulse travels to auditory nerve)

Question 9

__________ initates the tympanic reflex

Answer 9

loud sounds

Question 10

tympanic reflex

Answer 10

tensor tympani and stapedius muscles contract; sound transmission decreases (protective= prevents strong sound waves from causing excessive stimulation of the auditory receptors)

Question 11

round window

Answer 11

where sound waves exit the cochlea

Question 12

As sound wave move the fluids in the cochlea…

Answer 12

the basilar membrane vibrates and the stereocilia of the hair cells are bended

Question 13

When the inner hair cell is bent toward the tallest stereocilium, it is

Answer 13

depolarized (influx of K-> opens Ca channels -> vesicle release of neurotransmitters)

Question 14

when the inner hair cell is bent away from the tallest stereocilium it is

Answer 14

hyperpolarized ( no K influx-> no activation of calcium channels (no calcium influx)-> no positive ions in cell)

Question 15

hair cells are in what kind of ionic environment

Answer 15

endolymph: high potassium (outside), low sodium

Question 16

Inner Hair Cells

Answer 16

primary sensory receptors

Question 17

Outer Hair Cells

Answer 17

shorten when depolarized, increase the amplitude and clarity of sound

Question 18

How are different tones coded by the cochlea?

Answer 18

by different regions of the cochlea

Question 19

What part of the cochlea responses to low pitch?

Answer 19

near distal end

Question 20

What part of the cochlea responses to high pitch

Answer 20

near the round window

Question 21

Detection of the frequency of a sound above 5kHz is based on

Answer 21

the location along the cochlea of the most intensely stimulated hair cells

Question 22

For a frequency below 2000 Hz how is frequency detected

Answer 22

both firing pattern of CN8 and the region of hair cell activation can give the brain ideas about the pitch

Question 23

The frequency of the action potential is proportional to

Answer 23

the loudness of the sound

Question 24

Major Auditory Pathways (in order)

Answer 24

cochlear ganglia-> dorsal and vental cochlear nuclei ->superior olive -> inferior colliculi -> medial geniculate body (thalamus) -> primary auditory cortex

Question 25

dorsal and ventral cochlear nuclei

Answer 25

2nd order neurons respond from 1 ear (same side)

Question 26

superior olive

Answer 26

respond from both ears (where info crosses)

Question 27

inferior colliculi

Answer 27

centers of auditory reflexes

Question 28

primary auditory cortex

Answer 28

tonotropic, very plastic

Question 29

Superior Olive

Answer 29

sound localization: loudness difference (important for freq about 3000 Hz); detectable time difference (most important for frequencies below 3000 Hz)

Question 30

Conductive deafness

Answer 30

impared sound transmission external or middle ear; impairs all sound frequencies

Question 31

Sensorineural deafness

Answer 31

transmission of nerve impulses is impaired: loss of hair cells; impairs ability to hear some pitches more than others

Question 32

function of the pinna

Answer 32

protection; helps detect where sounds are coming from

Question 33

sound waves vibrate the eardrum which vibrates the 1, 2, 3. The foot plate moves in and out of the 4 and transfers energy to the 5

Answer 33

malleus, incus, stapes, oval window, endolymph cochlea

Question 34

Along the basilar membrane there are 2 types of sensory cells:

Answer 34

the outer and inner hair cells

Question 35

How are hair cells arranged

Answer 35

by the frequency they detect

Question 36

Where is the organ of corti located

Answer 36

cochlear duct or the scala media

Question 37

The ________ is filled with a fluid with an abnormally high K+

Answer 37

cochlear duct or the scala media