Postlab quiz 4 Flashcards
AIED =
Autoimmune Inner Ear Disease
What is autoimmune inner ear disease (3)
Progressive hearing loss and/or dizziness
Reduced hearing w/tinnitus
Attacks of dizziness (normal blood tests for antibodies)
What does autoimmune inner ear disease resemble
Meniere’s disease
Affects this many of the X million Americans with hearing loss
<1%, 28 million
Causes of autoimmune inner ear disease (5)
Antibodies/immune cells damage inner ear bystander damage cross-reactions intolerance genetic factors
What causes bystander damage
cytokines provoke extra immune reactions
What causes cross reactions
antibodies cause accidental damage
ear shares common antigens with potential pathogens
What causes intolerance
ear may only be a partially immune privileged locus
What effect do genetic factors have on AIED
possible increased susceptibility to hearing disorders
Signs and symptoms of AIED (4)
Hearing loss in one ear and rapid progression to second ear (can progress slowly)
Fullness in the ear
vertigo
tinnitus, hissing, or roaring sound
What is AIED often mistaken for
Otitis media
What are treatments for AIED (5)
Steroids like prednisone ore dexamethasone (short-term)
Cytotoxic agents like cytoxan or methotrexate (short-term)
Plasmapheresis
cochlear implant
cell and gene therapy
Exteroceptors
receptors that recieve stimuli from outside the body
interoceptors
receptors that receive stimuli from inside the body
Detect changes within the body
Where are interoceptors located
deep within muscles, tendons, and other structures
Exteroceptors are located
on the surface of the body (usually)
Our senses are comprised of these types of receptors
exteroceptors
Weber’s law states this
the size of the just noticeable difference, dI, is a constant proportion of the original stimulus, I
Weber’s fraction
The ratio of intensity difference to the initial weight intensity
Just noticeable difference or intensity difference is
the amount of stimuli needed to have a noticeable difference in our current stimulation state.
What is referred pain
pain that originates in one area of the body, but is perceived in another (ex. Heart attack)
What is done for the weber test (hearing)
The handle tip of a struck tuning fork is placed against the middle of the subjects forehead to determine if one ear is more deaf than the other
When doing the weber test for hearing what is the result if one ear hears the fork better than the other: sensorineural
The sound will be heard better in the normal ear because neural activity is essential for hearing
When doing the weber test for hearing what is the result if one ear hears the fork better than the other: conductive
The ear that hears the fork louder is the ear that is more deaf, due to the good ear having the sound masked by environmental noise
Conduction deafness can be simulated by doing this simple thing
plugging one ear with cotton
The Rinne test compares this
air conduction of sound with bone conduction of sound
The weber test for hearing should be conducted in a room with this level of noise
normal room noise
The Rinne test for hearing should be conducted in a room with this level of noise
A quiet room
What is done for the Rinne test (hearing)
Place the end of the handle of a struck tuning fork on the mastoid process. As soon as the sound is no longer audible through the bone hold the fork about 1 inch from the ear. The subject should be able to hear again.
If the should is heard through the bone longer the person has this type of deafness
conduction deafness
What are the expected results of the weber and rinne test for hearing for the following condition: no hearing loss
Weber: no lateralization
Rinne: Sound heard longer through air conduction
What are the expected results of the weber and rinne test for hearing for the following condition: conduction deafness
Weber: lateralization to the deaf ear
Rinne: sound heard as long as or longer through bone conduction than air
What are the expected results of the weber and rinne test for hearing for the following condition: sensorineural deafness
Weber: lateralization to the normal ear
Rinne: sound heard longer through air conduction
How is hearing loss quantified by an audiogram
If there is an increase of 20 dB above normal tone level the subject is sead to have hearing loss of 20dB for that tone
List the classifications of hearing loss in accending order
normal mild moderate severe profound hearing loss
What is a audiogram
an instrument for measuring hearing acuity that consists of an earphone conneted to an electronic oscillator.
Range of hearing tested in both types of audiogram tests
250-8000 Hz
500-2000 Hz
Frequency of normal speech
500-2000 Hz
What is a receptive field
sensory + visual neurons activated by stimuli that fall within a specific physical area (two point test)
Areas with large receptive fields
back, thigh
Areas with small receptive fields
finger tip
Lateral inhibition does this
Increases contrast between activiated receptive fields and inactive neighbors
Benefits of lateral inhibition
way of isolating location of stimuls
increase in sensory preception
Generator potentials 2 characteristics
caused by adequate stimuli in sensory cells
amplitude proportional to strength of stimulus
Another name for generator potentials
receptor potentials
2 characteristics of action potentials
all or none event
strength of stimulus determines frequency
Auditory pathway: external ear
Pinna
ear canal
Auditory pathway: middle ear
malleus, incus, stapes
Auditory pathway: inner ear
vestibular apparatus w/ semicircular canals
cochlea
Name of fluid found in inner ear
endolymph
What is the purpose of the vistibular cochlear nerve
Senses sound through the movement of hair cells in the cochlea
Characteristic of conduction deafness
sound cannot be transmitted through external/middle ear
Causes for conduction deafness (4)
plugged with earwax
fluid in middle ear
diseases
trauma to middle ear bones
characteristics of sensoryneural deafness
damage to structures of inner ear
Cause of sensoryneural deafness
death/damage of hair cells resulting from loud noises
What is the mechanism for referred pain
unknown
Types of receptors (6) (subcatagories)
chemoreceptor photoreceptor thermoreceptor mechanoreceptor nocireceptor proprioceptor
Types of receptors (2) Main
Tonic receptors
phasic recpetors
tonic receptors adapt at this speed, and example
slow
pain
phasic receptors adapt at this speed, and example
fast
most sensory receptors
Describe the action of tonic receptors
action potentials occur at a constant rate from the application of the stimuls to the removal
Describe the action of phasic receptors
Rate of the action potentials reduces after initial application of the stimulus
Once the stimulus is withdrawn we notice the absense of the stimuls
Describe chemoreceptor
senses chemical stimuli in the environment or blood
Describe photoreceptors
rods and cones in the retina of the eye
Describe thermoreceptors
respond to heat and cold
Different receptors for heat and cold
Describe mechanoreceptors
stimulated by mechanical deformation of the receptor cell membrane
Describe nocireceptors
pain receptors
describe proprioceptors
provide sense of body position and allow fine control of skeletal movements
hold balance
What is the law of specific nerve energies
the sensation characteristic of each sensory neuron is that produced by it’s normal stimulus, or adequate stimulus
What is a generator potential
graded depolarization produced by stimulation of sensory receptors that results in the production of action potentials by a sensory neuron
What is an action potential
all-or-none electrical event in an axon or muscle fiber in which the polarity of the membrane potential is rapidly reversed and re-established
Pathway of a sensation
sensory receptor experiences a generator potential
the axon-neuron reaches threshold and generates an action potential
The signal travels to the brain for integration
What must happen to generate an action potential
a generator potential must reach a depolarization threshold
This dictates the strength of the stimulus
the frequency of the action potential
more frequent = stronger
What do phasic receptors prevent
sensory overload
What is the typical neuron refered to as
multipolar neuron
What is used in the video to determine resting membrane potential
electrode attached to voltmeter
Depolarization =
stimulation
hyperpolarization =
inhibition
RMP in podcast is
-65 to -95 mV
What is disturbed when stimulus takes palce
RMP
Na+ Channels: The channel is close at this point
RMP
Na+ Channels: The channel is oppened by this
depolarization (AP)
Na+ Channels: The channel is inactived during this period
refractory period (absolute)
Na+ Channels: How is the channel inactiviated
opening blocked by a protein
Na+ Channels: These are examples of this type of channel
voltage gated
What opens voltage gated channels
ambient voltage
What is threshold (mv)
-50 mV
What is the top of the spike in the movie (mV)
+30
What resets RMP
Na/K pumps
Milliseconds per AP
4 mS
Action potential frequency is determined by
strength of stimulus
strong stimuli are felt more strongly bcause of this
the rate of action potentials (frequency)
Druing a absolute RP this occurs
incativiation of Na+ channels
Druing a relative RP this occurs
hyperpolarization due to efflux of K+
This would be needed to generate a AP druing a relative RP
greater than normal strength of stimulus
These types of neurons are mylinated
motor
sensory
Rate of impulse conduction: mylinated vs unmylinated
300 meter/s to 1 meter/s
The auditory tube connects with this and does this
pharynx
equalizes pressure
Pressure on the oval window causes this to the round window
causes it to move in and out
These muscles reduce vibration to protect from loud sound
tensor tympani muscle
stapedius muscle
The two scala and where are they in relaction to eachother and what is in them
Scala vestibuli
scala tympani
SV above ST
Perilymph
What is between the scalas and what does it contain
cochlear duct
endolymph
Name of the nerve going to the ear (number)
vestibulocochlear nerve (VIII)
Where is the spiral organ of corti
in the cochlear duct
What is the central core of bone (ear)
modeolas
name of the membrant that effects the hair cells
techtorial membrane
causes generator potentials
Place principle does this
allows us to identify different sound pitch by what ‘Place’ on the organ of corti the hair cells are disturbed
low frequency stimulate this region of the cochlear duct
distal
mid frequency stimulate this region of the cochlear duct
middle
high frequency stimulate this region of the cochlear duct
proximal
where is sensitive lost as we age (hearing)
high frequency (proximal)
Conduction deafness is caused by this
stoppage of conduction of sound waves
sensorialneural deafness is caused by
damage to hair cells / nerve
Where is the electrode inserted for a cochlear implat
scala tympani
