Flashcards in Occular and Vestibulocochlear systems Deck (72)
What is the function of the hair cell?
Transduction of the stimuli
If a hair cell is moved what occurs?
K+ enter via mechanically gated ion channels
Glutamate is released.
What dictates whether TMC-1 channels are open or closed?
Tilt of the cilia
What triggers the movement of the cilia?
Vibration of the tectorial membrane
What is the tectorial membrane?
One of two membranes within the cochlear.
What happens upon entry of K+ ?
Membrane depolarisation as endolymph has v.high K+ concentration.
What is tonotropy?
Ability to detect pitch
What membrane enables the detection of pitch?
Flexible so vibrates in sync with fluid motion.
How is the Basal Membrane able to detect pitch?
Width decreases the further along the basal membrane you go as width decreases flexibility increases.
This determines the distance a frequency will travel and in turn activate the afferent neurones specific to that area.
Higher frequency sounds are detected where?
Within the thinner regions of the basal ganglia.
Thinner the basal membrane the higher the frequency.
Inner hair cell
Main source of afferent signal in auditory VIII nerve
Outer hair cell
Controls stiffness to amplify membrane vibration
What is the function of Prestin?
Alters the length of the cell, when depolarised it contracts bringing the basal membrane closer to the tectoral membrane.
Contraction of Prestin does what?
Amplifies membrane vibration.
Which regions of the brain help locate the source of sound in space
Lateral and Medial superior olive
What is the basic understanding of what the lateral and medial superior olive does?
Works out from the fact that the ipsilateral side (to the sound) receives sound sooner than the contralateral from this time difference it generates an orientation and distance.
What is the main function of the vestibular system?
Where am I going and which way is up?
What do the Semicircular Canals do?
What do the Saccule Uctricle do?
What are the semicircular canals?
3x fluid filled chambers at right angles to each other.
Sheet of cells where hairs are clustered
Bulge along the canal where crista are located.
All orientated in the same direction
Project into the gelatinous cupola
Movement of the fluid shifts the cilia
Vestibular canals - Left Horizontal Turn
Excite left horizontal
Inhibit right horizontal
Vestibular canals - Right Horizontal Turn
Excite right horizontal
Inhibit left horizontal
Vestibular canals - Left Forward tilt
Left anterior excited
Right Posterior Inhibted
Vestibular Canals - Left Backwards tilt
Left Posterior Excited
Right anterior inhibited
Vestibular Canals - Right forward tilt
Left Posterior Inhibit
Right anterior excited
Vestibular Canals - Right backwards tilt
Excite right posterior
Inhibit left anterior