Auditory System

Front 1

A pure tone containing only one frequency of sound

a. will cause the stereocilia to bend in only the depolarizing direction.
b. will only cause the closure of stereociliary ion channels.
c. will cause a cyclical vibration of the cochlear partition at the same frequency as the tone.
d. will produce a hyperpolarizing Receptor Potential.
e. will, at low intensities, activate the entire cochlea.

Back 1

C. Will cause a cyclical vibration of the cochlear partition at the same frequency as the tone.

Front 2

During cyclical vibration of the Cochlear Partition up and down:

a. Inner Hair Cells release transmitter during both up and down cycles.
b. Auditory nerve fibres produce more APs during both cycles of vibration.
c. The basilar membrane vibrates only in the depolarizing direction.
d. The Hair Cell stereocilia are bent back and forth to open and close ion channels.
e. Depolarizing receptor potentials are produced in both cycles of vibration.

Back 2

D. The Hair Cell stereocilia are bent back and forth to open and close ion channels.

Front 3

Even in absolute silence there are still APs in all auditory nerve fibres to the brain because:

a. the eardrum is always vibrating by a small amount.
b. the outer hair cells are always releasing transmitter to these nerve fibres.
c. there is a standing current flow through some open ion channels in hair cell stereocilia.
d. the nerve fibres can control the transmitter they release.
e. K+ ions are entering the afferent fibres, through open ion channels.

Back 3

C. There is a standing current flow through some open ion channels in hair cell stereocilia.

Front 4

One way in which the middle ear can optimise delivery of sound energy to the cochlea is due to the fact that:

a. the stapes is attached to the round window of the cochlea.
b. there are more hair cells near the cochlea base to which the middle ear is attached.
c. the area of the tympanum is equal to the area of the oval window.
d. the tympanum acts like a lever.
e. the area of tympanum is greater than the area of the stapes footplate.

Back 4

E. The area of tympanum is greater than the area of the stapes footplate.

Front 5

Opening of ion channels in the stereocilia of hair cells of the cochlea:
Select one:
a. allows the movement of K+ ions down their concentration gradient.
b. allows the movement of K+ ions down their electrical gradient.
c. allows the movement of both Na+ and K+ ions
d. allows the movement of Na+ ions down their electrical gradient.
e. results in the hyperpolarization of the membrane potential of the hair cells.

Back 5

B. Allows the movement of K+ ions down their electrical gradient.

Front 6

Outer Hair Cells (OHCs) are responsible for:

a. modifying sounds in a way to help us identify the direction from which the sound is coming at us.
b. funnelling sound energy onto the stereocilia of Inner Hair Cells (IHCs).
c. transmitting to the brain, most of the information about sound.
d. deafness.
e. making vibration of the cochlea partition frequency selective and sensitive.

Back 6

E. Making vibration of the cochlea partition frequency selective and sensitive

Front 7

The afferent nerve fibres leaving the cochlea are frequency selective because:
Select one:
a. the vibration of the tympanum and middle ear bones is frequency selective.
b. the ion channels in the stereocilia are frequency selective.
c. the vibration of the stapes against the oval window is frequency selective.
d. the vibration of the cochlea partition is frequency selective.
e. there are more OHCs than IHCs making the vibration of the cochlea partition frequency selective.

Back 7

D. The vibration of the cochlea partition is frequency selective

Front 8

The basic role of the middle ear bones is

a. To move the eardrum in response to sounds.
b. To amplify sound energy to the cochlea.
c. To make vibration of the Cochlear Partition frequency selective.
d. To make vibration of the Cochlear Partition increase from the base to the apex and reach a peak depending on frequency.
e. To produce a depolarizing receptor potential.

Back 8

B. To amplify sound energy to the cochlea

Front 9

The receptor potential in the cochlear hair cells

a. is a hyperpolarization because of the breakdown of cyclic GMP.
b. is produced when chemicals bind to specialized receptor proteins in the stereocilia.
c. is produced by change in K+ conductance.
d. is produced when the stereocilia activate 2nd messengers.
e. is produced at the base of the hair cells by the opening of voltage-gated Ca++ channels.

Back 9

C. Is produced by a change in K+ conductance

Front 10

Vibration of the Cochlear Partition:

a. is, at the base of the cochlea, most sensitive to high frequencies and, at the apex, to low frequencies.
b. is maximal near the base and decreases towards the apex.
c. causes the eardrum to vibrate in turn.
d. sets in motion the vibration of the malleus, incus and then the stapes.
e. begins at the cochlear apex and increases towards the base.

Back 10

A. Is, at the base of the cochlea, most sensitive to high frequencies and, at the apex, to low frequencies.