Auditory and vestibular system physiology Flashcards
What is the organ of hearing?
Hair cell
Which neurotransmitter is involved in the auditory system?
Glutamate
Which ion is involved in hair cells?
Potassium
Which nerve endings will glutamate act on at the hair cell?
Efferent nerve endings
Will sound be amplified or reduced in the middle ear?
Amplified to allow it to travel in the fluid of the inner ear
What separates the scala vestibuli from the scala media?
Reissner’s membrane
What separates the scala media from the scala tympani?
Basilar membrane
Describe transduction in the corti hair cells?
Basilar membrane to tectorial membrane
What connects the scala vestibuli and the scala tympani?
Helicotrema
What windows does the sv and st connect with respectively?
SV = oval window ST = round window
Where can perilymph be found?
Scala vestibuli
Scala tympani
Where can endolymph be found?
Scala media
Describe the rigidity of the basilar membrane from the base to the apex?
Rigid at base
Floppy at apex
Where will high and low pitched sound be heard within the cochlea?
High = base Low = apex
Where will the rods of corti synapse?
Bipolar neurones with the cell body in the spiral ganglion
Will potassium move inwards or outwards in the organ or corti?
Inwards
Describe the components of perilymph and endolymph
Perilymph: high sodium, low potassium, glucose of 4
Endolymph: low sodium, high potassium, glucose of 0.5
Mutations in what can result in deafness?
Recycling of K+ in the endolymph
What will inner hair cells communicate with?
Main source of afferent signal
What is the input to outer hair cells?
Efferent inputs from the superior olivary complex
What is the function of outer hair cells?
Stiffness
Amplify membrane vibration
What protein is present on outer hair cells?
Prestin which can change the length of the cell
How does furosemide act in the middle ear?
Inactivates prestin damaging auditory system
What will outer hair cells respond to sound with?
Receptor potential
Change in length - movement of tectorial membrane
What does tonotopy ensure?
Each neurone innervates several different areas and different neurone types
What is tonotopy?
Spatial arrangement of where sounds of different frequencies are processed within the brain
What is the function of the medial superior olive?
Computes sound arrival at the 2 ears to generate an interaural time difference using a delay line
What is the function of the vestibular system?
Gaze and postural stability
Sense of orientation
Detection of linear and angular acceleration
What part of the vestibular system determines head angular acceleration?
Semicircular canals
What part of the vestibular system determines head linear acceleration?
Saccule = vertical Utricle = horizontal
Where can hair cells be found in the semicircular canals?
Crista at the ampulla
They will project into the cupula
In semicircular canals are the kinocilium orientated in the same or different direction?
SAME so all excited or inhibited together
Are the semicircular canals filled with endolymph or perilymph?
Endolymph
Where can otorocnia be found?
Otolithic membrane
What is the striola in the macula?
Structural landmark
Arranged otoconia into narrow trenches dividing otolith
This allows otolith organs to have multidirectional sensitivity
What are the 3 main vestibular reflexes?
VOR - eyes still in space as head moves
Vestibulo-colic reflex - keeps head still in space when you walk
Vestibular-spinal reflex - adjusts posture for rapid changes in position
