Sensory Physiology 2

Question 1

Sound waves can be seen as vibrations of a

Answer 1

tuning fork.

Question 2

The larger the amplitude of the oscillations, the

Answer 2

louder the sound

Question 3

how is sound measured?

Answer 3

measured in Decibels (dB).

Question 4

The more frequent the oscillations (frequency) the

Answer 4

higher pitched the sound. This is measured in Hertz (Hz).

Question 5

how many hz is the human range?

Answer 5

on average 20 to 20,000 Hz, although there is natural variation especially at higher frequencies.

Question 6

a gradual loss of sensitivity to higher frequencies with age is ….

Answer 6

… normal

Question 7

The dynamic range is

Answer 7

0 dB to 120-130 dB for middle frequencies between 1,000 – 2,000 Hz

Question 8

For lower and higher frequencies, the dynamic is

Answer 8

narrowed.

Question 9

All sound above …

Answer 9

90 dB are damaging to the inner ear with irreversible damage above 120 dB.

Question 10

Normal conversation/speech is around

Answer 10

60 dB.

Question 11

The size of vocal chords affects …

Answer 11

… the pitfch of voice

Question 12

Vocal folds are controlled via

Answer 12

recurrent laryngeal branch of the vagus nerve.

Question 13

what are the vocal folds composed of?

Answer 13

They are composed of twin infoldings of mucous membrane stretched horizontally, from back to front, across the larynx.

Question 14

how do the vocal folds vibrate?

Answer 14

They vibrate, modulating the flow of air being expelled from the lungs during phonation.

Question 15

The throat, nose/mouth cavities act as

Answer 15

resonating chambers.

Question 16

Most arthropods use antennae to

Answer 16

detect sounds.

Question 17

Nearby sound drives

Answer 17

fast-moving air molecules into the hairs on the mosquito’s antenna, causing the antennal shaft to vibrate (similar to a tuning fork).

Question 18

The outer and middle parts of the ear are both

Answer 18

air filled

Question 19

The outer and middle parts of the ear are both air filled, whilst the inner ear is

Answer 19

fluid filled.

Question 20

The fluid has much greater …

Answer 20

inertia than the air.

Question 21

How much sound do you hear when underwater?

Answer 21

If sound waves hit the surface of the fluid directly. Almost all the energy of the wave would be reflected back from the surface of the fluid and very little would be transmitted into the inner ear itself.

Question 22

Sound waves are detected by …

Answer 22

… the ear

Question 23

The pinna acts to …

Answer 23

direct the sound wave towards the auditory canal where it strikes the tympanim (ear drum), which forms the boundary between the outer and the middle ear.

Question 24

what is the tympanum ?

Answer 24

The tympanum is a tightly stretched membrane.

Question 25

when the sound wave hits the tympanum it is made to...

Answer 25

... vibrate at the same frequency as the oscillations of the sound wave.

Question 26

when the sound wave hits the tympanum it is made to vibrate at the same frequency as the oscillations of the sound wave. These movement cause ...

Answer 26

... the three ossicles (‘little bones’, the malleus, incus, and stapes (hammer, anvil, and stirrup)) of the middle ear to move, again at the same frequency, and to transmit the mechanical stimulus to the inner ear.

Question 27

The middle ear ensures

Answer 27

sound can overcome the greater inertia presented by the fluid filled inner ear.

Question 28

The middle ear does this through ...

Answer 28

area ratio and level action.

Question 29

whagts the oval widiow?

Answer 29

membrane covering the inner ear

Question 30

The oval window (membrane covering the inner ear) has an area

Answer 30

17 times smaller than that of the tympanum.

Question 31

The oval window (membrane covering the inner ear) has an area 17 times smaller than that of the tympanum. So, the force exerted on the tympanum is

Answer 31

increased 17-fold when transmitted to the oval window.

Question 32

The 3 ossicles act as ...

Answer 32

a level system to magnify the force of transmission by about 1.2-fold.

Question 33

The oval window or fenestra vestibuli is

Answer 33

a connective tissue membrane-covered opening from the middle ear to the cochlea of the inner ear.

Question 34

A travelling wave, as its name suggests, is

Answer 34

one that moves along, a good example being the wave on the seashore (as opposed to a stationary wave, which does not move, an example being the wave seen on a violin string).

Question 35

Inside, the cochlea is divided into

Answer 35

three fluid-filled chambers called scalae (‘scala’ means staircase in Italian): the scala vestibuli and scala tympani,

Question 36

Inside, the cochlea is divided into three fluid-filled chambers called scalae (‘scala’ means staircase in Italian): the scala vestibuli and scala tympani, both of which are filled with

Answer 36

perilymph that is rich in Na+ and low in K+, and the scala media, which is filled with endolymph that is rich in K+ and low in Na+.

Question 37

The cochlea is rather like the spiral of

Answer 37

a snail shell with about 2.5 turns and about the size of a large pea.

Question 38

Unravelled, the whole structure of the cochlea is approximately

Answer 38

32 mm in length.

Question 39

High frequency waves (high pitch) do not

Answer 39

travel far into the cochlea. Low frequency waves (low pitch) travel the furthest.

Question 40

The sense organ itself is

Answer 40

the organ of Corti, which sits in the basilar membrane, thus dividing the scala media from the scala tympani.

Question 41

Oscillations of the oval window set up a

Answer 41

travelling wave within the fluid of the scala vestibuli that causes the basilar membrane to oscillate up and down.

Question 42

The basilar membrane changes along

Answer 42

its length such that it is narrow and stiff at the base, adjacent to the oval window, and wide and floppy at the apex.

Question 43

The organ of Corti comprises two groups of hair cells

Answer 43

a single row of inner hair cells and three rows of outer hair cells.

Question 44

The stereocilia (‘hairs’) of the hair cells contact

Answer 44

the membrane above them (tectorial membrane).

Question 45

As the basilar membrane rises, ...

Answer 45

the tectorial membrane moves outwards and the stereocilia are bent. As the basilar membrane descends, the stereocilia straighten up. Therefore, the hair cells will be bending in synchrony with the frequency of the sound waves.

Question 46

As the stereocilia are bent in one direction, the hair cells

Answer 46

depolarize

Question 47

As the stereocilia are bent in one direction, the hair cells depolarize as they return in the reverse direction....

Answer 47

the channels close again and the flow of K+ is halted

Question 48

As the stereocilia are bent in one direction, the hair cells depolarize; as they return in the reverse direction the channels close again and the flow of K+ is halted. This means that the receptor potential in th e hair cells

Answer 48

depolarizes and repolarizes at the same frequency as the incoming sound

Question 49

The mechanoelectrical transduction channel is ...

Answer 49

... nonselective for cations with ion fluxes in hair cells composed predominantly of Ca2+ and K+.

Question 50

Upon normal stimulation,

Answer 50

ions flow from the extracellular space containing endolymph into the hair cell.

Question 51

Note the stretching of the activation gate: drives

Answer 51

K+ in

Question 52

Age-related hearing decline. Note the loss of:

Answer 52

- hearing threshold and - frequency detection

Question 53

The semicircular canals (left, in a) are arranged so

Answer 53

that they can detect: movements of the heads in the LM axis. the AP axis. the SI axis. rotational movements

Question 54

The utricle and saccule (right, in b) are arranged so

Answer 54

that they can detect: linear accelerations in the horizontal axis. the vertical axis. and thus gravity

Question 55

When motion/movement/rotation occurs:

Answer 55

inertia moves the cupula in opposite direction

Question 56

When motion/movement/rotation occurs: inertia moves the cupula in opposite direction, this creates

Answer 56

a sudden flow of endolymph,

Question 57

the sudden flow of endolymph is involved in

Answer 57

endolymph is K+-rich, opening of transduction channels, depolarisation of the hairs, excitation of the afferent fibers (CN VIII).

Question 58

endolymph is rich in...

Answer 58

K+

Question 59

The cupula is a

Answer 59

gelatinous mass. It has inertia

Question 60

The crista ampullaris is a

Answer 60

a ridge of tissue, to which hair cells are anchored to

Question 61

Axons convey action potentials from...

Answer 61

the hair cells to the vestibular nerve.

Question 62

what is the auditory vestibular nerve used for?

Answer 62

For both sound and balance.

Question 63

When the head is rotating or moving, whayt contriols eye movements?

Answer 63

CN VIII

Question 64

When the head is rotating or moving, CN VIII controls eye movements: what are these?

Answer 64

- slow (pursuit), - rapid (saccade). This induces a nystagmus.

Question 65

What is a cochlear implant?

Answer 65

a surgically implanted neuroprosthesis that provides a person who has moderate-to-profound sensorineural hearing loss with sound perception.