Ear Physiology Flashcards
What is the process called where sound energy is converted into action potentials in the auditory nerve fiber?
Sensory transduction in the hair cells of the organ of Corti
This process is crucial for hearing, as it allows sound waves to be interpreted by the brain.
What happens to the receptor potential when sound waves reach the inner ear?
Causing mild depolarization
This depolarization is essential for the conversion of sound energy into electrical signals.
What is the effect of the movement of stereocilia towards the kinocilium?
Results in hair cell depolarization
This movement opens K+ channels and increases action potentials.
What occurs when stereocilia move away from the kinocilium?
Leads to hyperpolarization
This movement decreases the likelihood of action potentials being generated.
What does the endocochlear potential relate to?
The electrical potential of cochlear fluids
This potential is vital for the functioning of hair cells in the cochlea.
What governs the action potential in the auditory nerve fiber?
The all-or-none law, with a definite threshold and refractory period
This ensures that action potentials are generated reliably in response to sufficient stimuli.
What is the resting state of hair cells regarding K+ ions?
K+ leaks into cells due to negative membrane potential and high apical [K+]
This contributes to the maintenance of the resting membrane potential.
What happens during mechanical deformation of stereovilli towards the kinocilium?
Opens cation channels, allowing K+ influx and cell depolarization
This process is essential for the mechanotransduction in hair cells.
What is the consequence of depolarization in hair cells, except for auditory outer hair cells?
Activates Ca2+ channels, triggering synaptic vesicle release
This neurotransmitter release is vital for transmitting auditory information to the brain.
What occurs when stereovilli deform away from the longer stereovilli?
Closes cation channels, leading to hyperpolarization
This hyperpolarization decreases the likelihood of neurotransmitter release.
Fill in the blank: The _______ is the fluid within the cochlea that has a high concentration of potassium ions.
Endolymph
Endolymph is crucial for the function of hair cells in the cochlea.
True or False: The movement of stereocilia towards the kinocilium causes K+ channels to close.
False
This movement actually opens K+ channels, allowing K+ to enter the cell.
What is the role of tip links in hair cells?
They connect stereocilia and facilitate mechanotransduction
Tip links are essential for the opening and closing of ion channels in response to mechanical stimuli.
What is the Rinne test?
A tuning fork test where a vibrating fork is placed on the mastoid process until no vibration or sound is felt/heard.
Used to evaluate hearing loss by comparing air and bone conduction.
What indicates normal hearing in the Rinne test?
Vibration still heard in air after bone conduction ceases.
This means air conduction is better than bone conduction.
What does a positive Rinne test indicate?
AC > BC = Normal hearing.
This means air conduction is better than bone conduction.
What does a negative Rinne test indicate?
BC > AC = Conductive loss.
This suggests that bone conduction is better than air conduction.
What is conduction deafness?
Air vibration not heard after bone conduction stops.
This indicates an issue with the outer or middle ear.
What is nerve deafness?
Both air and bone conduction diminished or lost.
This indicates a problem with the inner ear or auditory nerve.
What does the Weber test assess?
It assesses hearing loss by placing a tuning fork on the vertex of the skull or forehead.
It helps to determine the type of hearing loss.
What indicates normal hearing in the Weber test?
Sound heard equally on both sides.
This shows no significant hearing loss in either ear.
What does unilateral conduction deafness indicate in the Weber test?
Sound heard louder in the diseased ear.
This occurs due to the absence of masking effect of environmental noise.
What does unilateral nerve deafness indicate in the Weber test?
Sound heard louder in the normal ear.
This suggests a problem in the auditory nerve or inner ear.
Define sensorineural hearing loss.
Involving the inner ear, cochlea, or the auditory nerve.
This type of loss is often permanent.
Define conductive hearing loss.
Involving any cause that limits external sound from accessing the inner ear.
Common causes include cerumen impaction.
What is mixed hearing loss?
A combination of conductive and sensorineural hearing loss.
This indicates issues in both the outer/middle ear and inner ear.
What does dynamic equilibrium refer to?
Acceleration of the head in rotation, horizontal, and vertical movements.
It involves the vestibular system of the inner ear.
What is the Rinne test?
A tuning fork test where a vibrating fork is placed on the mastoid process until no vibration or sound is felt/heard.
Used to evaluate hearing loss.
What indicates normal hearing in the Rinne test?
Vibration still heard in air after bone conduction ceases.
This suggests that air conduction is functioning properly.
What indicates conduction deafness in the Rinne test?
Air vibration not heard after bone conduction stops.
This means that there is an issue in the conductive pathway.
What indicates nerve deafness in the Rinne test?
Both air and bone conduction diminished or lost.
This suggests a problem with the auditory nerve or inner ear.
What is the Weber test used for?
To evaluate hearing loss by assessing sound lateralization.
It helps differentiate between conductive and sensorineural hearing loss.
What does normal centralization in the Weber test indicate?
Sound heard equally on both sides.
This suggests normal hearing function.
In the Weber test, what does lateralization to the same ear indicate?
Conductive loss in that ear.
This occurs due to the absence of masking effect of environmental noise.
In the Weber test, what does lateralization to the opposite ear indicate?
Sensorineural loss in the tested ear.
This suggests that the normal ear is hearing better.
What is the difference between air conduction (AC) and bone conduction (BC)?
AC refers to sound traveling through the ear canal and eardrum, while BC refers to sound transmitted through the bones of the skull.
These are assessed in hearing tests.
What are the classifications of hearing loss?
- Conductive
- Sensorineural
- Mixed
Each type has different underlying causes and implications for treatment.
What does ‘AC > BC’ indicate?
Normal hearing.
This is a standard finding in healthy ears.
What does ‘BC > AC’ indicate?
Conductive loss.
This means that bone conduction is better than air conduction.
What is dynamic equilibrium?
The ability to maintain balance during head movements, including rotation and acceleration.
It involves structures like the ampulla and utricle in the inner ear.
What role do hair cells play in hearing?
They are involved in the detection of sound vibrations in the cochlea.
Their function is crucial for converting sound waves into neural signals.
What indicates a unilateral nerve deafness?
Sound heard louder in normal ear
What is dynamic equilibrium?
Acceleration of the head in rotation, horizontal, and vertical movements
What are the semicircular ducts involved in dynamic equilibrium?
- Anterior
- Lateral
- Posterior
What is the function of the cupula?
Stimulates hair cells and sends an impulse via vestibular nerve to cerebellum
What happens to endolymph during head rotation?
Endolymph lags behind due to inertia
What is the effect of head movement to the left on vestibular afferent fibers?
- Increase in firing on the right
- Decrease in firing on the left
What is mixed hearing loss?
A combination of conductive and sensorineural hearing loss
What does bending of stereocilia towards the kinocilium result in?
Depolarization and increase in impulses
What does bending of stereocilia away from the kinocilium result in?
Hyperpolarization and decrease in impulses
Fill in the blank: The _____ is pushed over and stimulates hair cells.
Cupula
What is the role of hair cells in the crista ampullaris?
Respond to fluid motion in the duct
What direction does the endolymph move during head rotation from left to right?
Opposite direction by inertia from right to left
What is the response of hair cells when the head rotates to the right?
Cilia of the right side bent towards the kinocilium, leading to depolarization
What are the supporting cells in the crista ampullaris?
Cells that support hair cells
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True
