1.7 Hearing and Balance senses
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1.7 Hearing and Balance senses
Hearing and balance
what does the inner ear consist off? (2)
-bony cavity (bony labyrinth)
-labyrinth lined with membrane (membranous labyrinth
The bony and membranous labyrinth are both filled with
*trash can liner in can
**area inside liner is filled with fluid
***area between liner and trash can is filled with different fluid
What 3 structures are on bony labyrinth?
Which fluid is in the bony labyrinth?
What are the concentrations like in perilymph?
- High NA
- Low K
What are the concentrations like in endolymph?
Which fluid is concentrated within membranous labyrinth?
Where does the cochlea begin?
At oval and round window
Where does the cochlea end?
What is the modiolus?
Central pillar of bone that cochlea is carved around
*mountain is the modiolus
*road built around is the cochlea
Membranes) vestibular (3)
-extends entire length of cochlea
-becomes wider as it extends from oval/round window to helicotrema
Chambers) how are these created?
what are the 3 chambers created by membranes?
***all extend length of cochlea
Between which 2 structures does scala vestibulli lie ?
Temporal bone and vestibular membrane
bw which 2 structures does cochlear duct lay?
Vestibular and basilar membrane
bw which 2 structures does scala tympani lay?
Basilar and temporal bone
Where does the organ of corti sit?
On basilar membrane
What is the Tectorial membrane attached to?
Auditory function) what is volume?
Auditory function) what is pitch?
Auditory function) what is timbre?
Range of decibels we can hear
.1 - 120 decibels
Range of hz we can hear?
What is the purpose of ossciles?
To amplify sound
What's significant about tympanic membrane and oval window vibrations
Since the tympanic membrane is 20x larger the sound waves exerted onto oval window are 20x greater than on tympanic membrane
What occurs after staples vibrates ? (2)
-creates perilymph waves in scala vestibuli
-perilymph waves push on vestibular membrane and causes endolymph waves which then causes basilar membrane to vibrate
What does basilar vibrations cause hair cells to do?
Starts to move and bend against the Tectorial membrane which causes depolarization
What does bending of Cilia cause?
Opening of K channels which will rush into the cell because theres a lot of it in endolymph
*this is what causes depolarization
Pitch ; basilar membrane)
-because the basilar membrane gets thicker as it extends to helicotrema the high pitches frequency is located by oval window and the low pitch at the helicotrema
Function of round window (2)
-pressure release valve
-absorbs excessive waves so only the strongest signals will be picked up and not have many different vibrations
-from hair cells to cochlear nerve to cochlear nucleus to thalamus to auditory cortex and some branches to inferior colliculus
Static labyrinth) vestibule
What are the utricle and saccule?
*analogous to cochlear duct
Macula with otolithic membrane is analogous to
Organ of corti
Each macula is located within saccule and utricle
What comes into contact with otolithic membrane?
Kinetic labyrinth ) how many semicircular canals are there? What positon
Kinetic labyrinth ) ampulla
Elevated base of canal
Kinetic labyrinth ) Crista ampullaris
Kinetic labyrinth ) cupula
Cup over hair cells
What does static labyrinth detect? (2)
-evaluates the position of your head relative to gravity
-linear acceleration or deceleration
Each macula is surrounded by?
Does macula move?
No its stationary but otolithic membrane is moveable
Transduction of balance
As head movement occurs, endolymph moves and pushed otolithic membrane while sliding over the hair cells bending their Cilia which are embedded in the membrane causing depolarization
Macula of utricle is oriented horizontally and responds to...
Macula of saccule is oriented vertically and responds to
Kinetic labyrinth) semicircular canals respond to
Rotational movements that why they are position the way they are to detect 3 dimensions
Within the membranous ducts of semicircular canals, what surround Crista and cupulla?
Is the cupola moveable?
*Crista is stationary
As head rotation occurs, endolymph...
Flows and moves cupola over the hairs of the Cristal causing the Celia to bend and depolarizing