Special Senses - Hearing and the Vestibular System Flashcards
Outer ear fxn
funnel sound waves into the ear
middle ear fan
impedance matching - sound wave has been moving through air, but now we are going to move it through fluid
inner ear
cochleas converts sound waves to action potentials
the two continuous fluid filled compartments of the cochlea
scala vestiboli and scala timpani
fluid inside the scala vestibuli and scala tympani
Perilymph
perilymph composition
simialar to the ECF
High Na, low K
Basilar and Reissner;s membrane create what chamber
scala media
the scala media is isolated from the _____ and is instead filled with ______
perilymph
endolymph
composition of endolymph
high in K, low in Na
will have a significant effect on the transduction of sound waves into action potentials
Perilymph
where
composition similar to
ion composition
scala vestiboli and scala timpani
CSF/ECF
High Na, low K
Endolymph
where
composition similar to
ion composition
scala media
intracellular fluid
high K, low Na
head motions are crucial for helping external ear funnel sound waves into ear. what do we do
turn our head towards the noise to improve the ability of the ear to collect sound waves (maximize the difference between ears for localization
The ______ transmit and amplify sound waves from tympanic membrane to _____
ossicles
oval window of cochlea
Inner ear physiology of sound
the impact of the stapes on the oval window causes the basilar membrane to vibrate at the same frequency of sound
the basilar membrane vibrates _____ with impact, _____ with release
down
up
high frequency sounds cause the maximum vibration of the basilar membrane where
closest to the oval window (short wavelength)
low frequency sounds cause the max vibration of the basilar membrane where
fastest away from the oval window, towards the helicotrema (long wavelength)
each hair cell is composed of a distinct arrangement of
shorter sterocilia that increase in length
are the stereo cilia true cilia
no
each stereo cilia is connected to another at the top by
an extracellular filamentous protein known as the TIP LINK
so they all move as one
During development, there is a since true cilium called
the kinocilium.
the tallest of the :hairs: on the hair cell
the kinocilium
the kinocilium ____ around the time of birth
degenerateds
when sound causes the basilar membrane to vibrate what happens in the tectorial membrane? how does this affect the hair cells?
the connections between the basilar membrane and the tectorial membrane cause the tectorial membrane to move as well
this motion bends the hair cells
If steriocilia are bent TOWARDS The kinocilium (or where it used to be) the hair cell
depolarizes
if the stereo cilia move away from the kinocilium, the hair cell
hyperpolarizes
bending the hair cells towards the kinocilium opens
K channels that depolarize the cell
- due to the composition of the endolymph, K enters the hair cells and causes it to depolarize
The path of auditory processing splits into
two parallel paths in the cochlear nuclei
The ventral path processes
temporal and spectral features of sound
the dorsal path integrates the
acoustic information with somatosensory information for localizing sound
medial superior olive generates
a map of the intramural time differences (how the sound arrived at the two ears differently) microseconds matter
lateral superior olive generates
a map of the intramural intensity differences (how the sound arrived at the two ears differently)
the amplitude of the ound when it reaches the scond ear is slightly reduced
time and intensity differences are crucial information in
determining where a sound originated from
the inferior colliculus
supresses information related to echoes and arrives at a final estimation of sound location on the horizon
the superior colliculus
takes the location data from the inferior colliculus and adds the third dimension to it VERTICAL HEIGHT to create the spatial map of the sound;s location
The primary auditory cortex A1 has a _____ representation of sounds
tonotopic
More rostral areas of A1 are activated by
low frequency sounds
more caudal areas of A1 are activated by
high frequency sounds
The Auditory Association cortex is composed of______. Purpose?
several different types of areas
has neurons that are activated by complex sounds. Purpose ois processing of complex sounds, i.e. music, identification of sound (naming) and speech
Linear acceleration occurs in
the horizontal or vertical plane
angular acceleration requires
rotation around one or more planes
Types of angular acceleration
can spin around vertical axis
can fall forward
can fall backward
In real life, most motions are
combinations of several accelerations
swelling where the three semicircular ducts connect
utricle
below the utricle
saccule
acceleration is detected by
semicircular ducts
utricle
saccule
each is oriented to be best at detecting acceleration in one of the planes
What type of fluid is found int the vstibular apparatus
endolymph (high K)
what type of fluid surrounds the vestibular apparatus
perilymph (high Na)
utrical detects
linear motion along horizontal plane
saccule detects
linear motion in a vertical plane
Horizontal aka lateral canals detect
horizontal turning motion
posterior semicircular canal detects
falling posterior
falling backwards
the anterior semicircular cana detects
falling anterior
falling foward
process of activating different vestibular organs
movement of hair cells in one direction is excitatory, movement in the opposite direction inhibits
in semicircular canals ____ is specialized for acceleration
ampulla
in utricle and saccule, the _____ is specialized for acceleration
macula
otolith organs
utricle and saccule
organs with cupula
semicircular ducts
how do we go from activating vestibular organs to sending information to brain
motion of the body (particularly the head) will produce motion of the endolymph in the appropriate vestibular organ, bending the hair cells in the ampullae or macula (depending on the type of motion) and activating the nerves
regardless of which way we are falling/moving, reflexes are designed to
keep our focus on the horizon (a spot directly in front of us)
as I spin, eyes rotate
horizontally until i can no longer physically focus on that spent, at which time they jump to pick a new spot
fall forward, eyes move
up
fall backward, eyes move
down
If the anterior semicircular canal is active, the ______ is activated while the ____ is inhibited
superior rectus m
inferior rectus m
eyes move up to continue to focus as you fall forward
if the posterior semicircular canal is active, the ___ is activated while the _____ is inhibited
superior oblique m
inferior oblique m
eyes move down to continue to focus on a point as you fall backwards
if the horizontal (lateral) semicircular canal is active, the ________ is active while the _______ is inhibited in the eye ipsilateral to the rotation.
The control lateral eye activates the ________ and inhibits the _______.
medial rectus
lateral rectus
lateral rectus
medial rectus
eyes move left or right to continue focus as you spin around
role of cerebral cortex and cerebellum in the integration of vestibular information and the control of gaze
the vast majority of the cortical and cerebellar involvement in the vestibulooptic reflexes is to suppress the reflex to allow for voluntary motion
