Topic 8.5

Question 1

Speed of sound in air

Answer 1

343 m/s

Question 2

Characteristics of sound (3)

Answer 2

• frequency
• intensity
• phase difference

Question 3

Types of sound (3)

Answer 3

• Pure tone
• Real sound
• Noise

Question 4

What is real sound made of?

Answer 4

fundamental frequency (pitch) + overtone

Question 5

dB equation

Answer 5

dB = 20*log (Pa/Pref)

Question 6

At which frequency is our hearing the sharpest?

Answer 6

2000 Hz (needs the least intensity to hear it)

Question 7

Range of human hearing

Answer 7

20-20 000 Hz

Question 8

What are the ossicles

Answer 8

malleus, incus, stapes

Question 9

What can reduce the movement of the ossicles?

Answer 9

stapedius and tensor tympani muscles

Question 10

What does the stapes connect to?

Answer 10

The oval window

Question 11

What does the inner ear contain?

Answer 11

Cochlea and vestibular apparatus

Question 12

What are the parts of the cochlea?

Answer 12

Bony and membranous labyrinths

Question 13

3 compartments of the cochlea

Answer 13

• scala vestibuli
• scala media
• scala tympani

Question 14

Which part of the cochlea receives vibration first?

Answer 14

scala vestibuli

Question 15

What comes after scala vestibuli?

Answer 15

scala tympani (loops back around)

Question 16

What separates the scala tympani and scala media?

Answer 16

basilar membrane

Question 17

What separates scala vestibuli and scala media?

Answer 17

reissner’s membrane

Question 18

What is scala tympani connected to?

Answer 18

round membrane

Question 19

Where is the organ of corti located?

Answer 19

in scala media

Question 20

What does the organ of corti contain?

Answer 20

rows of inner and outer hair cells

Question 21

How many inner hair cells?

Answer 21

3500

Question 22

What do inner hair cells detect?

Answer 22

They detect the actual vibration

Question 23

Which hair cells have contact with the tectorial membrane?

Answer 23

The outer hair cells

Question 24

How many outer hair cells?

Answer 24

16 000

Question 25

Role of outer hair cells (2)

Answer 25

• detect low amplification sound (they are basically amplifiers)
• dampening mechanism

Question 26

2 mechanisms of amplification in the middle ear

Answer 26

• decrease in area (oval window < tympanic membrane)

- lever system of the ossicles

Question 27

What is the important plasma membrane protein of the outer hair cells?

Answer 27

prestin

Question 28

What is prestin?

Answer 28

a motor protein capable of causing contraction without the use of ATP and calcium signaling

Question 29

What does contraction of the hair cells do?

Answer 29

enhance upward movement of the basilar membrane and cause endolymph to flow out

Question 30

Sound identification (3)

Answer 30

• intensity : rate coding mechanism
• frequency : place coding mechanism
• spatial localization : phase difference

Question 31

Which channels open when stereocilia are moved?

Answer 31

transient receptor potential channel type A1

Question 32

endolymph potential in vestibule and cochlea

Answer 32

• vestibule : 0mV

- Cochlea : 80mV

Question 33

Em of hair cells

Answer 33

-40mV

Question 34

Electrical gradient in cochlear hair cells

Answer 34

120mV

Question 35

K+ and Na+ in scala tympani and scala vestibuli

Answer 35

K+ : 2mM

Na+ : 140 mM

Question 36

K+ and Na+ in scala media

Answer 36

K+ : 150 mM

Na+ : 1mM

Question 37

Where is the endolymph generated?

Answer 37

in the stria vascularis

Question 38

Afferentation of signal

Answer 38

• spiral ganglion
• cochlear nerve
• cochlear nuclei
• superior olivary nucleus
• lateral lemniscus
• inferior collicular nucleus
• nucleus of medial geniculate body
• primary auditory cortex

Question 39

Primary auditory cortex

Answer 39

in temporal lobe, broadmann area 41