Auditory Vestibular Flashcards
What is transduction
When physical energy is changed to neural energy
Bones of the middle ear
Malleus
Inces
Stapes
The 2 rigid connections in the middle ear
Connection between the typanic membrane and the malleus
Connection between the malleus and the incus
Flexible connection in the middle ear
Connection between the incus and the stapes
What is impedance matching?
When sound reaches fluid in the ear, most of it is reflected back and lost (due to impedence mismatch) so the middle ear bones make up for this and increase sound pressure
What is greater - the impedence of air or water?
The impedance of water is much bigger
What does Reissner’s membrane separate?
Separates the SV from the SM (scala vestibuli from the scala media)
What does the basilar membrane separate?
Separates the SM from the ST (scala media from the scala tympani)
Where is the organ of corti and what is it responsible for?
Located in the cochlea at the basilar membrane
Responsible for transduction
Effect of sound on the basilar membrane
The width and flexibility of the basilar membrane determines the distance a particular frequency travels
What does force TOWARDS the kinocilium do?
Opens TRPA1 channels and K+ enters DEPOLARISING cell
What does force AWAY from TRPA1 channels do?
Shuts channels
What happens in hair cell transduction?
The tectorial membrane vibrates
The hair cells bend
Depending on how they bend, the hair cells release neurotransmitter
The neurotransmitter released in the hair cell are captured in the nerve fibres
The neural energy is sent to the brain
Difference between the inner and outer hair cells?
Inner hair cells are the MAIN source of afferent signal in the auditory nerve
Outer hair cells primarily get EFFERENT inputs. Control stiffness, amplify membrane vibration
What do outer hair cells do?
Primary efferent inputs
Control stiffness and amplify membrane vibration
What detects head rotation?
The semicircular canals
What detects head linear acceleration/translational motion/gravity (and by extension head tilt)
Saccule and utricle
What is the crista?
Sheet of cells where hair cells are clustered
Orientation of the Kinocili
Orientated in the same direction so all excited or inhibited together
What do the otolith organs sense?
Sense linear acceleration and gravity
these are the utricle and saccule
What is the vestibulo-ocular reflex
Keeps the eyes still in space when the head turns
What is the vestibulo-colic reflex?
Keeps the head still in space - or on a level plane when you walk
What is the vestibulo-spinal reflex?
Adjusts posture for rapid changes in position
Why can alcohol cause vestibular system dysfunction?
Alcohol is less dense than water so gets into the blood and then into the cupula
The cupula then becomes less dense and floats in the endolymph a bit more
The cupula bends a litter more than usual away from the ground
This bends hair cells as if you are rotating even when you are still
This gives you the sensation of rotating when you are still.
You are drunk.
