Karteikarten
Hearing
Karten in diesem Stapel (134)
- 1What is sound?Regions of compressed (high pressure) and rarefied (low pressure) air caused by vibrations and energy moving through the air
- 2What is frequency of sound?Number of sound waves per second
- 3What are the units for sound frequency?Hertz (Hz)
- 4What audible property of sound is determined by frequency?Pitch
Low frequency = low pitch
High frequency = high pitch - 5What is the amplitude of sound?Intensity or loudness
- 6What are the units for amplitude of sound?Decibels (dB)
- 7What is the range of hearing in humans?Wide range of hearing
20 Hz - 20 kHz - 8What is the range of amplitudes that can be detcted by humans?Wide range of intensities or amplitudes (dynamic stage)
- 9What is the auditory field?Range of audible frequencies and amplitudes for a species
- 10What is the consequence of sound levels above the auditory field?Damage and pain
- 11What is the consequence of sound levels below the auditory field?Cannot hear
- 12What affects the threshold for sound at different amplitudes?Frequency
More sensitive to sound at certain frequencies - 13At what frequency is the lowest threshold for sound in humans?1-2 kHz (conversation area)
- 14What is meant by shifting of the audiometric curve in different species?Hearing more sensitive at different frequencies
- 15What structure separates the external and middle ear?Tympanic membrane
- 16Which part of the ear contains the ossicles?Middle ear
- 17Which part of the ear contains the sensory apparatus?Inner ear
- 18Which part of the ear is known as the 'conductive zone'?External and middle ear
- 19Describe how sound waves are conducted to the inner earSound vibrates tympanic membrane
Ossicles move
Press on membrane that marks entrance to inner ear (oval window) - 20What is impedance matching?Difference in surface area between the tympanic membrane and oval window causes amplification
- 21Why is impedance matching important?Amplification required as more energy required to move fluid than air
- 22What percentage of sound energy would be transferred without impedance matching?0.1%
- 23Which 2 muscles are involved in the ossicular reflex?Stapedius
Tensor tympani - 24What is the location of the muscles involved in the ossicular reflex?Connect ossicles to outer bones of the ear
- 25What is the function of the ossicular reflex?Protective against loud sounds above 70 dB
- 26How do the muscles of the middle ear carry out the ossicular reflex?Loud sound causes sustained shortening of muscles
Stiffen levers to reduce energy conduction - 27Why can the ossicular reflex be useful with lots of low frequency noise present?Aids discrimination
- 28Above which frequency does the ossicular reflex not have a role in humans?1-2 kHz
- 29Why is the ossicular reflex ineffective for impulse noise?50-100 ms delay
- 30What is the shape of the mammalian cochlea?Compartmentalised spiral
- 31What is the size of the cochlear spiral in man?35 mm
- 32Why are altricial species often born deaf?Cochlea partially developed at birth
- 33What is the term for the auditory epithelium?Organ of Corti
- 34Where is the auditory epithelium located?Flexible basilar membrane
- 35How many rows of outer and inner hair cells are there?3 rows outer
1 row inner - 36Where are the cell bodies of the nerves innervating the auditory hair cells located?Spiral ganglion
- 37How are hair cells held rigidly?Supporting cells
- 38What is the main specialisation of sensory hair cells?Stereocilia
- 39What is the difference in potassium ion composition in perilymph and endolymph?Endolymph high K+
Perilymph low K+ - 40What is the electrical potential of endolymph?80 mV
- 41What is the electrical potential of perilymph?0 mV
- 42What is the location of endolymph?Bathes stereocilia
- 43What is the location of perilymph?Bathes basolateral membrane of hair cells
- 44How are endolymph and perilymph kept separate in the cochlea?Compartmentalisation
- 45What prevents endolymph leakage through the hair cells?Tight junctions
- 46What is the difference in the arrangement of hair cells in birds?Not arranged in rows
- 47What is different about the ossicles in birds?1 ossicle called the columella
- 48What organ do birds have instead of the organ of Corti?Basilar papilla
Same function as organ of Corti but not coiled - 49What are the 2 types of hair cells in birds?Long and short
- 50What is the arrangment of stereocilia in inner hair cells?Flat rows
- 51What is the arrangement of stereocilia in outer hair cells?V-shaped rows
- 52Are all stereocilia the same length?No - stepped arrangement with different lengths of stereocilia
- 53What are It channels of hair cells?Transduction channels
- 54Which channels are found in inner hair cells?IK - transport potassium out of cell
L-type calcium channels - 55Which channels are found in outer hair cells?IK
- 56Do inner or outer hair cells have the most afferent innervation?Inner hair cells
- 57What is the name of the motor protein within outer hair cells?Prestin
- 58Do inner or outer hair cells receive most efferent innervation?Outer hair cells
- 59Which neurotransmitter is found at the efferent synapses of outer hair cells?Acetylcholine
- 60How does movement of endolymph cause movement of hair cells?Movement of fluid by ossicles causes movement of basilar membrane
Hair cells move with basilar membrane
Tectorial membrane in which stereocilia are embedded remains still
Shearing of stereocilia against tectorial membrane = displacement - 61Describe how movement of stereocilia induces action potentials in the afferent neuroneTip links connect stereocilia
Displacement causes tip links to open mechanically gated transduction channels
High potassium enters cell = depolarisation
Stimulates opening of Ca2+ channels
Ca2+ influx releases neurotransmitter - 62What type of channel is the mechanically gated transducrtion channel?Non-specific cation channel
- 63Approximately how many inner hair cells are there?3500
- 64How many afferent terminals are there per inner hair cell?10-20
- 65What channel is characteristic of inner hair cells?Inward calcium channels (L-type Ca2+)
- 66What is the function of inner hair cells?Encode sound
- 67What is the electrical potential of the inner hair cell?-55 mV
- 68What is the electrical potential of the endolymph?+80 mV
- 69What is the quantitative driving force for potassium entry into the inner hair cell?135 mV
- 70What is the movement of inner hair cells required for perceptible sound?0.3 nm
- 71At what displacement do inner hair cells become saturated?20 nm
- 72What is meant by tonic activity in inner hair cells?Some transducer current present at rest
- 73What is the effect of displacement of inner hair cells in the positive direction?Depolarisation
Increase in transducer current - 74What is the effect of displacement of inner hair cells in the negative direction?Hyperpolarisation
Decrease in transducer current - 75What is the effect of different displacement directions on receptor activity?Wave of positive and negative activity
- 76What is meant by phase locking?Action potential frequency linked to phase and frequency of stimulus wave
- 77How does phase locking occur?Increase in graded receptor potential
More calcium influx
More neurotransmitter released
Increase in action potential frequency - 78What is tonotopy?Spatial arrangement of sound perception
- 79How does the structure of the basilar membrane enable tonotopy to occur?Basilar membrane has regional variations in fibrous structure
Therefore, region of maximum displacement depends on frequency of stimulus - 80What is the effect of low frequency sounds on basilar membrane displacement?Closer to apex
- 81What is the effect of high frequency sounds on basilar membrane displacement?Closer to base
- 82Where in the hearing apparatus is tonotopy set up?Cochlea
- 83Where in the auditory pathways is tonotopy maintained?All the way to cortex
- 84What is the function of tonotopic maps?Spectral analysis of sounds
- 85How does tonotopy occur in the auditory cortex?Isofrequency maps
- 86Where are tonotopic maps found as well as the auditory cortex?Superior colliculus
- 87How is tonotopy generated in hair cells?Maximally displaced at certain specific frequencies
- 88How is tonotopy maintained in afferent nerves?Characteristic frequency
- 89How is sound amplitude encoded?Populations of afferent nerves - high, medium and low spontaneous rate fibres
- 90What are high spontaneous rate fibres?Activates at low sound levels and easily saturated
- 91What are medium spontaneous rate fibres?Activated at medium sound levels
- 92Do medium spontaneous rate fibres saturate?Yes, but at higher sound levels than high spontaneous rate fibres
- 93What are low spontaneous rate fibres?Activated when sound levels are high
- 94What is the function of low spontaneous rate fibres?Can detect changes in sound at very high sound levels
- 95How many afferent synapses are there per inner hair cell?10-20 afferent synapses
- 96Approximately how many outer hair cells are there?12 000
- 97What is the shape of hair bundles on outer hair cells?V or W shaped
- 98Do outer hair cells mainly receive afferent or efferent innervation?Efferent
- 99What is the name of the motor protein in lateral membranes of outer hair cells?Prestin
- 100Which neurotransmitter is present at efferent synapses of outer hair cells?Acetylcholine
- 101Which channels are present in outer hair cells?IT = transduction channel
IK = outward potassium channels
No calcium channels - 102What is the function of outer hair cells?Amplification and tuning
- 103What is meant by tuning of auditory receptors?Response to lower frequency range
- 104How do outer hair cells allow amplification?Depolarisation activates motor protein prestin
Contraction of outer hair cells
Pulls on basilar membrane and amplifies movement of membrane
Increased hair cell activation = amplification - 105How do outer hair cells allow frequency?Pulling on basilar membrane
Sharper peak = narrower frequency range activated
Greater frequency discrimination - 106Which system modulates amplification and tuning by outer hair cells?Efferent system
- 107What are the consequences of loss of outer hair cells?Hearing loss (loss of amplification effect)
Poor frequency discrimination - 108What is the quantitative hearing loss that occurs with loss of outer hair cells?60 dB
- 109What are otacoustic emissions?Sound reflecting back through the ear
- 110What causes otacoustic emissions?Activity in outer hair cells
- 111What is the clinical relevance of otacoustic emissions?Diagnosis
- 112List the pathway nerves take from cochlea to auditory cortexSpiral ganglion
Ventral cochlear nucleus
Superior olive
Inferior colliculus
Medial geniculate nucleus of hypothalamus
Auditory cortex - 113What happens to auditory nerves at the ventral cochlear nucleusBifurcation to ipsilateral and contralateral superior olive
- 114What is meant by the binaural auditory pathway?Information from both ears reaches a neuronal population
- 115At what level does the auditory pathway become binaural?Superior olive
- 116How are low frequency sounds localised?Comparison of time at which same phase of a sound arrives at each ear - there is an interaural delay of the wave peak
- 117Where does information from each ear converge?Superior olive
- 118How are high frequency sounds localised?Interaural intensity difference
- 119How is rotational location of sound (e.g. in front or behind) determined by the pinnae?Mobile pinnae
- 120How is elevation of sound (up or down) determined by the pinnae?Folded pinnae
Combined properties of direct and reflected sound characteristic of elevation - 121Which part of the ear is affected in conductive deafness?External or middle ear
- 122What is the main cause of sensorineural deafness?Loss of hair cells and/or neurones
- 123Which part of the ear is affected in sensorineural deafness?Inner
- 124Give 3 reasons why a dog may develop sensorineural deafnessCongenital - associated with certain breeds
Noise damage
Ototoxic drugs which are toxic to hair cells - 125Give an example of an ototoxic drugAminoglycoside antibiotics
- 126Which animals can replace their sensory hair cells?Mammals do not replace their sensory hair cells
Birds and lower vertebrates do - 127Will loss of outer hair cells cause sensorineural deafness?No - some residual hearing will remain
- 128How can congenital deafness manifest?Can be born deaf or can be progressive
- 129Which specific function in the inner ear is usually disrupted in congenital deafness?Maintenance of endolymph
- 130How can an animal's appearance be associated with deafness?Lack of pigmentaton - pale irises and white coats
- 131What is Preyer's reflex?Response to sound with movement
- 132How does Preyer's reflex manifest in dogs?Elevation and rotation of pinnae
- 133What is the most objective diagnostic test for deafness?Brainstem auditory evoked response
Electrodes placed on head and used to detect neural activity in response to auditory stimulus - 134In what context is the objective diagnostic test for deafness most often used?Screening for breeding programmes in referral practices
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- Beschreibung
- BVSc Animal Health Science 2 (Special Senses) Karteikarten am Hearing, erstellt von Florence Edwards am 22/02/2017.
- Erstellt von
- Florence Edwards · Feb 2017
- Aktualisiert
- 6 Apr 2018
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