Hearing Flashcards
what is the function of the
a) outer ear [2]
b) middle ear [3]
c) inner ear [2]
d) central auditory nS [1]
what is the function of the
a) outer ear: protec, localisation amplicafication
b) middle ear: impedance matching (allows collection of energy to move from larger tympanic window to much small er oval window), pressure equalisation, inner ear stimulation (energy contained within sound isnt reflected away from inner ear)
c) inner ear: sound filterting & signal transduction in nerve endings
d) central auditory nS: information processing
which of the following used electricochemical as its mode of operation?
a) outer ear
b) middle ear
c) inner ear
d) central auditory nS
which of the following used electricochemical as its mode of operation?
a) outer ear
b) middle ear
c) inner ear
* *d) central auditory nS**
which of the following used mechanical vibration as its mode of operation?
a) outer ear
b) middle ear
c) inner ear
d) central auditory nS
which of the following used mechanical vibration as its mode of operation?
a) outer ear
- *b) middle ear**
c) inner ear
d) central auditory nS
which of the following used air vibration as its mode of operation?
a) outer ear
b) middle ear
c) inner ear
d) central auditory nS
which of the following used air vibration as its mode of operation?
- *a) outer ear**
b) middle ear
c) inner ear
d) central auditory nS
which of the following uses mechanical, hydrodyanmic and electricochemical as its mode of operation?
a) outer ear
b) middle ear
c) inner ear
d) central auditory nS
which of the following uses mechanical, hydrodyanmic and electricochemical as its mode of operation?
a) outer ear
b) middle ear
* *c) inner ear**
d) central auditory nS
what is the function of the concha & pinna? [1]
gathers sound energy and focuses / concentrated it on the meatus
which part of the ear divides the outer ear with inner ear?
- eustachian tube?
- cochlea
- round window
- tympanic membrane
- malleus
which part of the ear divides the outer ear with inner ear?
- eustachian tube?
- cochlea
- round window
- tympanic membrane
- malleus
the malleus, incus and stapes are components of the middle ear, what is their function? [1]
transfer vibrational energy from tympanic membrane to oval window (tympanic membrane is greater in size than oval window, so needs amplfying
what are the middle ear osicles? [3]
function? [1]
- malleus
- incus
- stapes
transfer sound energy from tympanic membrane to oval window
which ossicle does tensor tympani muscle connect to? [1]
what does activation of tensor tympani muscle cause to occur? [2]
- connects to the malleus medially
- increased tension in tympanic membrane
- causes modification of sound transfer within middle ear!! dampens sound sensitivty (ear protection)
- *- suppresses sounds coming from within own head (**e.g. chewing)
what are name of auditory reflexes? [2]
what are the two functions of the auditory reflexes? [2]
what are name of auditory reflexes? [1]
- attentuation reflex
- startle reflex
what are the two functions of the auditory reflexes? [2]
- prevent damage to person & ear
- enable distinguish important sounds v background
attenuation reflex
a) activated by? [2]
b) relies on which muscles? [1]
c) function? [1]
attenuation reflex
a) activated by?: own voice / loud sounds
b) relies on which muscles: activation of middle ear muscles
c) function: dampens out low frequency sounds: improves ability to distinguish speech
what is the startle reflex characterised by/ [2]
what is the startle reflex characterised by [2]
- *- ducking down** **to protect neck
- blinking**
what is the cochlea? [2]
which canals does it contain? [3]
what is the cochlea?
- bone with spiral structure
- contains organ responsible for transducing sound energy
which canals does it contain? [3]
- scala tympani: allows send energy to ascend in the cochlea to the apex
- scala vestibuli: spirals otherway and ends at round window
- scala media
(spiral shape of the cochlea allows for differing frequencies to stimulate specific areas along the spiral)
what is the name of the organ in the cochlea that is responsible for sound transduction (converts mech signals into electrical signals)
***** how is perception of sound occured in this organ [2]? *****
**organ of corti
- contains inner hair cells: stereociliar of inner hair cells**
signal to afferent fibres in afferent nerve (provide sound sensation)
- contains outer hair cells: stereociliar of outer hair cellsmodify transduction of low level sounds (motor function: can modify vibrations sensed by inner hair cells & amplify low level sounds
what is structure of inner hair cells like found in the cochlea?
a) upper part [3]
b) lower part [3]
stereocilia of inner hair cells structure:
- *top part:
i) ** stereocilia that are interconnected by cell adhesion molecules
ii) contain K+ channels.
iii) surroundered by endolymph (more like ECF, more like ICF: high K, low Na) - *bottom part:**
i) surroundered by perilymph (more like ECF - low K, high Na)
ii) Ca2+ gate channels
iii) afferent nerve fibres close by
explain mech of how nerve impulse is sent from inner hair cell in cochlea?
- when stereocilia tether (cell adhesion bit) becomes strained, the ion gate opens and K+ moves into the sterocilia.
- occurs because at rest membrane potential of hair cell is negative (across the whole cell), so when the K+ channels open, K+ moves in. **depolarises the cells
-**
stereocilia become displaced / move
- opens K+ channels
- depolarises the cell
- causes Ca+2 channels to open lower down the cell
- causes exocytosis of vesicles
- fused with membrane
- causes NT to diffuse across and activate afferent nerve !
-
what does it mean that transduction of sound frequency occurs in tonotopic way in ear? [2]
transduction of sound freq occurs in tonotopic way:
- *high frequencies** generate maximum displacement near the base of the cochlea
- *lower frequencies** generate displacment near the end (caled the helicotrema)
WHY?
- due to mechinal and elastic properties of the membran
how do you measure loudness?
what is the scale ?
use decibels (dB)
decibel is a ratio: dB = 20log P/Pr, where P = pressure of incoming sound, Pr = pressure of reference of just audible sound
auditory threshold, 140 = loud rock group
* what is the minimum audibility curve? ! *
what are the units?
where do u see silence on it, where is painful?
why are we less sensitive to high & low frequency sounds?
why are we less sensitive to high & low frequency sounds?
bc energy of sounds doesnt make it into cochlea
explain pathway of hearing in spinal tracts xx
primary order neuron: spiral ganglia in cochlea, axons form auditory nerve & synapse in medulla
secondary order neuron: medulla –> pons. axons collaterals decussate = bilateral asecension. synapses form in the olivery nuclei (helps determine location of sound)
goes to ML & primary sensory cortex
how do synapses differ from L & R ear if the sound does not come from distance that is equidistant?
e.g:
sound reaches left ear first: left ear connects to neurons in olivary nuclei first
sound reaches right ear second: connects to neurons in olivary nuclei second
when comes from left ear first / louder on left: AP from left ear can penerate further in olivary nuclei c.f. from right.
if timing is similar: convergence occurs
what is webers test?
how do u test?
vibrating tuning fork on middle of forehead & ask patient which ear it is heard.
normal patient = equally heard
conduction deafness = sound is louder in affected ear
sensorineural deafness = sound is louder in unaffected ear
