Hearing Flashcards Preview

MD1 Neuroscience > Hearing > Flashcards

Flashcards in Hearing Deck (63):
1

What is exophthalmia?

Eyes bulging out

2

What are wavelengths/frequency perceived as?

Pitch

3

What is amplitude perceived as?

Loudness

4

What is waveform perceived as?

Tone/timbre

5

What moves the ossicles?

Tympanic membrane

6

What moves the oval window?

Ossicles

7

What transforms the physical motion of the oval window into a neural response?

Cochlea

8

What is the function of the ossicles?

Match impedance of air to impedance of fluid in inner ear

9

How is the pressure increased at the oval window?

Tympanic membrane 20 times larger
Lever action of ossicles

10

By how much is the pressure increased at the oval window compared to the tympanic membrane?

200 times

11

What are the chambers of the cochlea?

Scala vestibuli - superior
Scala media - middle
Scala tympani - inferior

12

Where is the hearing apparatus located in the cochlear chambers?

Between scala media and scala tympani

13

What is the basilar membrane?

Coiled part of cochlea

14

What is the structure of the basilar membrane?

Wider at apex than base
Stiffer at base

15

Which part of the basilar membrane responds to high frequencies?

Base

16

Which part of the basilar membrane responds to low frequencies?

Apex

17

How does the stapes move fluid in the inner ear?

Moves against oval window to move fluid

18

Which cells are the auditory receptors?

Hair cells

19

What is the cell type of hair cells?

Specialised epithelial cells

20

Where are the hair cells located?

Between basilar membrane and reticular lamina

21

How are the hair cells moved?

Pushed and pulled between basilar membrane and reticular lamina

22

What is the function of the organ of Corti?

Where sound waves transduced to neural signals

23

What are the two types of hair cells?

Inner
Outer

24

Which type of hair cell are there more ov?

Outer

25

How many stereocilia does each hair cell have?

100

26

What causes a neuronal signal?

Bending of stereocilia

27

What is the function of stereocilia of outer hair cells?

Amplify sound

28

What is the function of stereocilia of inner hair cells?

Transduce sound to electrical signal

29

What force moves stereocilia?

Shear force

30

What is the status of potassium channels, and thus membrane potential of hair cells?

K channels partially open
Cell partly depolarisd

31

What does deflection of the hair bundle towards the tallest stereocilium cause?

Opening of K channels > more K into cell > depolarisation

32

What does deflection of the hair bundle towards the shortest stereocilium cause?

Closing of K channels > less K into cell > hyperpolarisation

33

What does depolarisation of hair cells cause?

Opening of voltage-gated Ca channels

34

What neurotransmitter is released by the depolarisation of hair cells?

Glutamate

35

Which is larger in hair cells: depolarisation or hyperpolarisation?

Depolarisation

36

What structure recycles potassium in the cochlea?

Vasa vascularis

37

Through what structures does potassium cycle in the cochlea?

Scala tympani > scala media > hair cell > scala tympani

38

What is the proportion of inner hair cell nerves projecting to brainstem nuclei?

95%

39

How do outer hair cells amplify sound?

Amplify movement of basilar membrane because attached to tectorial membrane

40

From which structure do outer hair cells receive efferent input?

Superior olivary complex

41

How do outer hair cells accentuate the movement of the basilar membrane?

Depolarisation > cell contraction
Hyperpolarisation > cell elongation

42

What is the protein in outer hair cells that changes in size depending on membrane potential?

Prestin

43

What is the auditory pathway?

Ear
- Hair cells
- CN VIII
- Spiral ganglion
Brainstem
- Cochlear nucleus in medulla
- Superior olive
- Lateral lemniscus
Midbrain
- Inferior colliculus
Thalamus
- Medial geniculate nucleus
Temporal lobe
- Auditory cortex

44

Where does auditory information decussate?

At cochlear nucleus

45

What mediates sound localisation

Relay nuclei in brainstem

46

What are the parts of the superior olivary complex?

Lateral superior olive
Medial superior olive
Trapezoid body

47

What is the function of the superior olivary complex?

Localise sound in horizontal domain

48

What does the medial superior olive do?

Localise sound by measuring time delay
- Only for low frequencies

49

What does the lateral superior olive do?

Loalise sound by sensing intensity differences
- Only for high frequencies

50

How is sound localised in the medial superior olive?

Neurons from both ears synapse on same neuron in medial superior olive
Time delay between two signals measured

51

How is sound localised in the lateral superior olive?

Head acts like shadow
Ear closer to sound hears a greater intensity than ear on other side > lateral superior olive detects difference in excitation from two ears
Further inhibition of other lateral superior olive via medial nucleus of trapezoid bodies

52

What is the Brodmann's area of the auditory cortex?

Area 41

53

Where is the auditory cortex?

Herschl's gyrus in temporal lobe

54

How are neurons organised in the auditory cortex?

By frequency - tonotopically organised
Alternating regions of input from both ears
Core area and belt area around it

55

To which hemisphere are speech sounds lateralised?

Left

56

To which hemisphere are environmental sounds lateralised?

Both

57

To which hemisphere is music lateralised?

Right

58

What does the dorsal pathway encode?

Where

59

What does the ventral pathway encode?

What

60

Where do the dorsal and ventral pathways converge?

Prefrontal cortex

61

What are some peripheral causes of sudden hearing loss?

Meningitis
Guillain-Barre
Acoustic neuroma
Metastasis

62

What is a central cause of sudden hearing loss?

MS

63

What is a cochlear cause of sudden hearing loss?

Infection
- HSV
- Autoimmune disease
- Trauma
- Metabolic
- Vascular
- Ototoxicity

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