Power Point 14

Question 1

________ - frequency is determined by the number of compressed patches of air per unit time that arrive at the ears. Unit: hertz (Hz) = cycles/sec

Answer 1

Pitch

Question 2

Loudness – intensity – ___________

is the difference in pressure between compressed and rarefied patches of air.

Answer 2

amplitude

Question 3

The stages of the basic auditory pathway:

Answer 3

Sound wave moves the tympanic membrane.
Tympanic membrane moves the ossicles.
Ossicles move the membrane at the oval window.
Motion at the oval window moves fluid in the cochlea.
Movement of fluid in the cochlea causes a response in sensory neurons.

Question 4

Three main divisions of the ear:

Answer 4

Outer ear, middle ear, inner ear.

Question 5

_________ amplify sound pressure onto the oval window.

Answer 5

Ossicles, Ossicles act like levers. Oval window is much smaller than the tympanic membrane.

Question 6

what two membrane-covered holes at the base:

Answer 6

oval window (contact with ossicles) and round window.

Question 7

Interior of the cochlea consists of two fluid-filled compartments (termed _______).

Answer 7

scalae, Scala media is the middle compartment. Scala vestibuli and scala tympani are one continuous compartment, however in cross section they appear as two separate chambers.

Question 8

what pair of elastic membranes separates scala media from the outer compartment

Answer 8

:• Reissner’s membrane • basilar membrane

Question 9

The basilar membrane is the organ that mediates ______ transduction

Answer 9

auditory

Question 10

The basilar membrane at the ______ is broader, thinner, and floppier than the ______

Answer 10

apex, base

Question 11

The membrane is tuned to different frequencies on each point along its length (apex = _____ frequency, base = ________).

Answer 11

lowest, highest

Question 12

Frequencies are represented along the basilar membrane in a continuous array = _____

Answer 12

tonotopy

Question 13

The ____________ acts as a mechanical frequency analyzer, separating complex sounds into their constituent frequencies, each analyzed in a distinct physical location.

Answer 13

basilar membrane

Question 14

The _________ is a thin strip of specialized epithelial cells – the auditory hair cells, and their support cells

Answer 14

organ of Corti

Question 15

_____________ is a shelf covering the organ of Corti. When the basilar membrane vibrates, shearing motion relative to tectorial membrane causes displacement of the cilia of the auditory hair cells

Answer 15

Tectorial membrane

Question 16

________ hair cells form a single row

Answer 16

inner

Question 17

Inner hair cell cilia bundles are pyramidal. The hair bundle extends from the cell’s _______ surface, into the ________. The bundle comprises about 60 cilia arranged in stepped rows of varying length

Answer 17

apical, scala media

Question 18

Each hair cell is surrounded by supporting cells, forming ________ with its neighbors (like between skin cells)

Answer 18

tight junctions

Question 19

On the _______ surface inner hair cells receive afferent (about 10 per inner hair cell) and very few efferent synapses

Answer 19

basal

Question 20

Inner hair cells receive more then ___% of spiral ganglion neurons’ contacts.

Answer 20

95

Question 21

______ hair cells lie in three rows, farther from the central axis.

Answer 21

outer

Question 22

On the ______ surface outer hair cells receive very few afferent and robust efferent synapses

Answer 22

basal

Question 23

Which types of cells do we have more of? inner or outter

Answer 23

outter

Question 24

_________ of the outer hair cells are equipped with special motors (voltage-sensitive motor protein prestin) that connect to cytoskeleton (actin, spectrin) on the cytoplasmic side of the plasma membrane. This mechanism is unique to the outer hair cells and allows them to extend and contract in response to electrical stimulation.

Answer 24

lateral walls

Question 25

________ are Tuned to a Particular Frequency and Arranged Tonotopically

Answer 25

Hair Cells

Question 26

Each hair cell is most sensitive (has the lowest threshold) to stimulation at a particular frequency = _________

Answer 26

best frequency

Question 27

Best frequencies of adjacent hair cells differ by about ___% (adjacent piano strings are tuned to be about 6% apart)

Answer 27

0.2

Question 28

The frequency sensitivity of a hair cell may be displayed as a ________

Answer 28

tuning curve

Question 29

The tuning curve is a graph of a sound intensity required to elicit response in a hair cell at a range of frequencies. It is typically ___-shaped

Answer 29

V

Question 30

__________________:Direct mechanical gating of K+ channels in the cilia; Electrical tuning allowing for atomic-scale precision in discrimination of sound-wave oscillations, and immediate (no delay) depolarization.

Answer 30

Mechanoelectrical Transduction

Question 31

_____________: stepwise differences in hair cell cilia lengths and rigidity, and their tonotopic arrangement.

Answer 31

Mechanical tuning

Question 32

___________: non-linear frequency-specific feed-back amplification in the cochlea due to somatic electromotility of the outer hair cells.

Answer 32

Cochlear amplifier

Question 33

Unusual ionic concentrations in the endolymph are generated by transport processes in the stria vascularis. These ionic concentrations are responsible for the ________

Answer 33

endocochlear potential

Question 34

Endolymph:

Answer 34

high K+, low Na+

Question 35

Perilymph:

Answer 35

low K+, high Na+

Question 36

Ordinary extracellular fluid, the ________, bathes the basolateral surface of hair cells.

Answer 36

perilymph

Question 37

A special saline solution, the ________ bathes the cells’ apical site.

Answer 37

endolymph

Question 38

A bundle of _________ projects from the apical surface.

Answer 38

stereocilia

Question 39

Stereocilia are Linked by

Answer 39

Tiplinks

Question 40

_____ influx into the cell from the surrounding endolymph results in depolarization, opening of the voltage-gated calcium channels and the release of neurotransmitter onto spiral ganglion neurites

Answer 40

K+

Question 41

Enhanced firing =

Answer 41

depolarization

Question 42

Decreased firing =

Answer 42

hyperpolarization

Question 43

_________ = continuous firing – modulated by both depolarization and hyperpolarization

Answer 43

Ribbon synapses (glutamate is the principal neurotransmitter)

Question 44

Inner Auditory Hair Cells are _____________Tuned to Specific Frequencies

Answer 44

Electrical Resonators

Question 45

The lengths of the hair bundles vary systematically along the _________ axis.

Answer 45

tonotopic

Question 46

Somatic electromotility:

Answer 46

Outer hair cells are tuned to specific frequencies, arranged tonotopically, and sound-evoked depolarization drives oscillations in the cell’s length.

Question 47

__________ is the motor protein (expressed in outer, but not in the inner hair cells), that translates depolarization into whole-cell rhythmic oscillations

Answer 47

Prestin

Question 48

___________:Somatic electromotility of the outer hair cells increases hearing range and discrimination in mammals

Answer 48

Cochlear amplifier

Question 49

__________ are sounds produced by movements of the basilar membrane in the absence of an external auditory stimulus

Answer 49

Otoacoustic emissions

Question 50

Efferent fibers robustly innervate outer hair cells, providing feed-back connections that modulate cochlea sensitivity. Principle neurotransmitter – _________

Answer 50

acetylcholine

Question 51

________ code: Afferent fibers are tonotopically organized.

Answer 51

Place

Question 52

_________ code: Sound waves oscilations and firing rates are co-linear.

Answer 52

Frequency

Question 53

Information conveyed by the auditory fibers encodes _______

Answer 53

pitch, volume, and timing