Auditory & The Vestibular System Flashcards
1
Q
What are hair cells?
A
Motion detecting mechanoreceptors
2
Q
What are hair cells used to detect?
A
- Movement of surrounding water
- Self movement in water
- Sound waves of different frequencies
- Lateral movement of the head
- Rotational movement of the head
- Direction of gravity
3
Q
Describe a hair cell in general
A
- A small nerve cell
- Doesn’t have an axon
- Sits embedded within the tissue with its apical membrane
- Has a bundle of stereocilia sticking out of the tissue
4
Q
What are the stereocilia bundles sticking out?
A
Thin processes that are rigid since they have actin cytoskeleton
5
Q
How does the cell correspond to not having an axon?
A
- It makes vast glutamatergic sinuses with the dendrites of afferents
- These afferents carry the signal to the brain
6
Q
How is the glutamate then released?
A
- Released by depolarisation
- As it happens, these cells have quite a depolarised membrane potential
- Around -40 Mv
7
Q
How does the hair cell signal?
A
- Signals the movement of fluid within the Stereocilia compartment
- Does so by the help of tip links
- Tips of each stereocilia is linked to the side of the wall of the next tool
- The base of the stereocilia tip linked have mechanically gated channels
8
Q
When do the mechanically gated channels open? (PART 1)
A
- Open when the tip links are put under tension
- Happens if the tip links move the fluids in the taller tip direction then it pulls on the tip link becomes stretched
- Pulls open those channels and causes the cell to depolarise
9
Q
When do the mechanically gated channels open? (PART 2)
A
- This then causes the release of more glutamate
- Which then causes the dendrites of the afferents to start generating action potential
10
Q
What happens if the Tip links go in the other direction?
A
- The Tip links begin to slack
- This closes the channels that are open at rest
- Causing the cell to become even more negative inside and causing less glutamate to be released
- The afferent then has a pause in its firing
11
Q
What is the gelatinous structure?
A
- Transfers force to the stereocilia
- Ensures that movement of fluid in the stereocilia compartment will maximally effect and appropriately affect the sterile cilia
12
Q
What is the bony labyrinth?
A
- The primary chamber that has been chiselled out of the bone
- It’s filled with perineum which is an extracellular fluid
- High in sodium, Low in potassium
- Within that, there are inner chambers which separate from the pyramids containing parts by membrane (Membrane labyrinth)
13
Q
What does the membrane labyrinth form?
A
- Forms a continuous space running through all these parts of the structure
- Filled with Indolence which is high in Potassium and low in sodium
- Also carries an excess of positive charge creating a potential difference between the endolymph and the rest of the nody
14
Q
What is the Cochlea?
A
- The auditory part of the system
- Has like a snake shell in structure
- Has a coil which contains an inner membrane out compartment known as the cochlear duct
15
Q
What happens in the membranous compartment?
A
- Movement of fluid within the membrane compartment tilts the stereocilia of the hair cells in the cochlea
- This causes them to depolarise and hyper polarise
