Occular and Vestibulocochlear systems Flashcards Preview

Neurology Year 3 > Occular and Vestibulocochlear systems > Flashcards

Flashcards in Occular and Vestibulocochlear systems Deck (72)
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1

What is the function of the hair cell?

Transduction of the stimuli

2

If a hair cell is moved what occurs?

K+ enter via mechanically gated ion channels
Glutamate is released.

3

What dictates whether TMC-1 channels are open or closed?

Tilt of the cilia

4

What triggers the movement of the cilia?

Vibration of the tectorial membrane

5

What is the tectorial membrane?

One of two membranes within the cochlear.

6

What happens upon entry of K+ ?

Membrane depolarisation as endolymph has v.high K+ concentration.

7

What is tonotropy?

Ability to detect pitch

8

What membrane enables the detection of pitch?

Basal Membrane
Flexible so vibrates in sync with fluid motion.

9

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.

10

Higher frequency sounds are detected where?

Within the thinner regions of the basal ganglia.
Thinner the basal membrane the higher the frequency.

11

Inner hair cell

Main source of afferent signal in auditory VIII nerve

12

Outer hair cell

Efferent input
Controls stiffness to amplify membrane vibration

13

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.

14

Contraction of Prestin does what?

Amplifies membrane vibration.

15

Which regions of the brain help locate the source of sound in space

Lateral and Medial superior olive

16

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.

17

What is the main function of the vestibular system?

Where am I going and which way is up?

18

What do the Semicircular Canals do?

Head rotation
Head angle
Acceleration

19

What do the Saccule Uctricle do?

Linear acceleration
Gravity

20

What are the semicircular canals?

3x fluid filled chambers at right angles to each other.

21

Crista

Sheet of cells where hairs are clustered

22

Ampulla

Bulge along the canal where crista are located.

23

Cilia

All orientated in the same direction
Project into the gelatinous cupola
Movement of the fluid shifts the cilia

24

Vestibular canals - Left Horizontal Turn

Excite left horizontal
Inhibit right horizontal

25

Vestibular canals - Right Horizontal Turn

Excite right horizontal
Inhibit left horizontal

26

Vestibular canals - Left Forward tilt

Left anterior excited
Right Posterior Inhibted

27

Vestibular Canals - Left Backwards tilt

Left Posterior Excited
Right anterior inhibited

28

Vestibular Canals - Right forward tilt

Left Posterior Inhibit
Right anterior excited

29

Vestibular Canals - Right backwards tilt

Excite right posterior
Inhibit left anterior

30

Otolith organs

Utricle - Horizontal
Saccule - Vertical