CNS audotiry

Question 1

What does the amplitude of a sound wave correspond to?

Answer 1

Its loudness.

Question 2

What is sound?

Answer 2

Pressure waves moving past your head.

Question 3

What does the frequency of sound correspond to?

Answer 3

The number of cycles per second, which indicates pitch.

Question 4

What is the normal audibility curve?

Answer 4

It depicts the relationship between how you perceive sound: the frequency of the sound waves (pitch) depending of the loudness of the sound (amplitude).

Question 5

What is the formula for a dB?

Answer 5

dB = 20 log (sound pressure / reference pressure)

Question 6

Going from 20 dB to 60 dB means that the sound amplitude has gotten […] times larger. Explain why.

Answer 6

100 X, since every 20 dB equals 10 X more.

Question 7

How does the damage threshold differ from the pain threshold?

Answer 7

The pain threshold exists above the damage threshold, meaning that you can damage your hearing without necessarily feeling pain.

Question 8

What frequency range do humans hear best?

Answer 8

100 to 10,000 Hz

Question 9

What is the damage threshold for audibility?

Answer 9

Around 85 dB

Question 10

What is the pain threshold for audibility?

Answer 10

At low frequencies, around 160 dB and within our typical audible range, around 130-140 dB.

Question 11

Why is presbycusis?

Answer 11

It is the gradual loss of the ability to hear high frequency sounds will age.

Question 12

Describe the major parts of the ear from outside to inside.

Answer 12

Pinna, external auditory canal, tympanic membrane, middle ear (malleus incus and stapes connected to eustachian tube), inner ear (cochlea).

Question 13

What is the function of the pinna?

Answer 13

It is shaped in order to reflect sound into the ear canal.

Question 14

What is the function of the eustachian tube?

Answer 14

It connects the middle ear to the throat.

Question 15

What is the function of the cochlea?

Answer 15

It is where transduction occurs.

Question 16

Where are the semicircular canals located and what is their function?

Answer 16

They are by the cochlea in the inner ear

Question 17

What is the oval window?

Answer 17

The oval window is a membrane-covered opening in the cochlea of the inner ear that receives vibrations from the stapes, the final ossicle in the middle ear. These vibrations create fluid waves in the cochlea, allowing sound to be converted into electrical signals sent to the brain.

Question 18

Describe the trajectory of sound up to its arrival in the inner ear.

Answer 18

1. Sound waves enter the ear canal and reach the tympanic membrane and causes it to vibrate
2. These vibration pass through the ossicles
3. The stapes presses agains the oval window, sending the sound waves into the inner ear

Question 19

What are the three bones in the middle ear and what is their function?

Answer 19

Malleus, incus and stapes. They do amplification of the sound

Question 20

The movement of the middle ear bones is mediated by […]

Answer 20

skeletal muscles

Question 21

How does the activity of the inner ear bones change in a very noisy environment?

Answer 21

The muscles contract to reduce movement of the ossicle and so minimizing the amplification

Question 22

Where is the round window located and what is its function?

Answer 22

It is just below the oval window
Its main function is to act as a pressure release valve: it moves outward in response to the inward movement of the oval window

Question 23

Explain how sound energy travels once it has gotten into the inner ear.

Answer 23

When the sound waves have crossed the oval window, the vibrations spread through the cochlear fluid. The fluid waves travel along the cochlear and causes the basilar membrane to vibrate in different areas due to it’s mechanical properties

Question 24

The motion of the basilar membrane is dependent on […]

Answer 24

the frequency of the sound

Question 25

What part of the basilar membrane vibrates when the sound is low frequency?

Answer 25

The end

Question 26

What part of the basilar membrane vibrates when the sound is high frequency?

Answer 26

The beginning

Question 27

What part of the basilar membrane vibrates when a complex sound is played?

Answer 27

Multiple parts, depending on the frequency break down

Question 28

Where are the utricle and saccule located and what is their function?

Answer 28

They are in the vestibule of the inner ear. They are part of the vestibular system and are responsible for detecting linear accelerations (such as moving forward or upward) and head position relative to gravity

Question 29

Describe the structure of the organ of corti and the key cells in it.

Answer 29

It's in the cochlear duct and on the basilar membrane. In it, there are hair cells with stereocilia that are embedded in the tectorial membrane

Question 30

Where are ion channels located in the ear?

Answer 30

in the tips of the stereocilia

Question 31

How many rows of each type of hair cells are there in the organ of Corti?

Answer 31

3 rows of outer hair cells and 1 row of inner hair cells

Question 32

Explain how the basilar membrane interacts with the hair cells and the effect produced.

Answer 32

When the basilar membrane moves, the cells follow that movement, but the stereocilia in the tectorial membrane (gelly) move the other way. The difference in movement causes the channels to open or close

Question 33

How do the properties of outer hair cells differ from those of inner hair cells

Answer 33

The outer hair cells are electromobile. They receive input from the brain to enhance certain frequencies over others

Question 34

Outer hair cells […] when depolarized and […] when hyperpolarized.

Answer 34

shorten lengthened

Question 35

What is the hypothesized function of hair cell electromotility?

Answer 35

they augment basial membrane motion

Question 36

Hair cells contain what kind of receptors?

Answer 36

mecano receptors

Question 37

How does the transduction process occur in hair cells?

Answer 37

When the k+ channels are open at the surface of the stereocilia, the hair cells releases neurotransmitters to the afferent neuron

Question 38

Mechanotransduction at the […] activates […]

Answer 38

hair cells afferent neurons

Question 39

Explain how the tip links activate afferent neurons.

Answer 39

Each stereocilia's Mecano receptor is connected to the one below, so when they are pulled apart, the receptors open and depolarize the hair cell

Question 40

What direction of stereocilia movement opens the ion channels?

Answer 40

Pulled apart/ towards the taller ones

Question 41

K+ causes [hyperpolarization/depolarization] of the membrane of hair cells, because […]

Answer 41

depolarization it's bringing more positive ions inside

Question 42

What is tinnitus?

Answer 42

ringing in the ears

Question 43

What are the two types of tinnitus?

Answer 43

Transient and chronic

Question 44

Explain how auditory information travels from the afferents to its final destination.

Answer 44

The 8th cranial nerve brings the information to the medulla, where ipsilateral and contralateral neurons are activated to reach the primary auditory cortex

Question 45

What is the purpose of the auditory pathways being bilateral?

Answer 45

Bilateral representation comes with a delay in reaching each hemisphere of the primary auditory cortex. It helps localize the sound better

Question 46

Describe how cochlear implants work.

Answer 46

Electrode are placed to stimulate the basilar membrane in an approximate way

Question 47

What are the major vestibular organs?

Answer 47

The semicircular canals, the utricle and the saccule

Question 48

What is the function of each of the vestibular organs?

Answer 48

The 3 semicircular canals detect angular acceleration in the three planes (all about 90° from each other) The urticle detects horizontal acceleration The saccule detects vertical acceleration

Question 49

What is the vestibular ocular reflex?

Answer 49

Even if the head is moving, the eyes can compensate and keep the gaze steady

Question 50

How does transduction occur in the vestibular organs?

Answer 50

The same stereocilia are present in the semicircular canals. This time, they are in the cupula

Question 51

Describe the organization of the semicircular canals.

Answer 51

The semicircular canals have an ampulla which is an enlargement in which we can find the hair cells and the stereocilia in the cupula

Question 52

Describe how the semicircular canals respond to movement.

Answer 52

The fluid in the semicircular canals is in some inertia meaning that the movement of the head will also cause the opening or closing of the ion channels

Question 53

Describe how the utricle and saccule adapt to motion.

Answer 53

The otoliths are floating above the stereocilia and will move them because of inertia

Question 54

What causes dizziness and motion sickness

Answer 54

Dizziness: once the rotation is done for a long time, the fluid wants to keep moving after stopping. This will give a perception of spinning Motion sickness: there is a conflict between the vestibular and the visual information being sent