Hair Cells Flashcards
What is the shape of the outer hair cells?
cylindrical
Which cells are jug like in shape?
Inner hair cells
What do inner hair cells have more of than outer hair cells?
Mitochondria and motor proteins
In what shape are the inner hair cells arranged?
A slight curved shape
In what shape are the outer hair cells arranged?
A sharpe ‘M’ shape
Are the inner hair cells placed over the basilar membrane?
Not always, they can also be placed on the osseous spiral lamina
Are the outer hair cells placed over the basilar membrane?
Yes, always
What is another (technically incorrect) name for a hair cell?
cilia
What are the tallest cilia called?
Sterocilia
What is the lid on the organ of corti called?
Tectorial Membrane
How does the membrane move?
In a sharing affect
What hairs are impacted by this movement?
The outer hair cells, they get caught in the shearing effect and can be damaged by harsh vibrations because they are imbedded in the BM
How do afferent nerve fibres work?
They send messages from the periphery to the central nervous system
How do efferent nerve fibres work?
They send messages from the brain to the periphery an are almost always inhibitory. They can only say stop or turn off
How many afferent nerve fibres connect to the inner hair cells?
10,000-20,000
How many afferent nerve fibres connect to the outer hair cells?
15,000-20,000 and they are shred between 3-5 hair cells
How do efferent nerve fibres connect to the hair cells?
There are very few efferent fibres and they do not connect directly with the hair fibres. They connect to the afferent nerve fibres that come from the hair cells.
What is Mechano-Electrical Transduction?
It is the transfer of energy from mechanical to electrical.
How does Mechano-Electrical Transduction work?
Hair fibres turn the mechanical energy into electrical messages by exciting the nerves through the tip links in the hair cells.
What are tip links?
Tip links are where the shorter hair cells connect to the taller hair cells.
What is the Trap Door Theory?
The tip links act like a rope putting on the trapdoor, opening and closing the the hole in the cilia (hair cells). This allows the endolymph that are high in potassium and more positively charged to flow through the trap door.
What is Prestin?
Prestin is a special motor protein called Piezoelectric and changes shape with a change in voltage
What is the Theory of Prestin?
Hair cells are covered in Prestin. In a resting state, prestin looks like a pacman with an open mouth. As soon as the voltage changes they snap shut (positive charge they are open, negative charge they are closed). When they are closed the cell is shorter than when it is open. This allows the cell to track the sound perfectly.
What is the main function of outer hair cells?
They amplify sounds
What is the risk that outer hair cells face?
Damage with loud noise due to the vibration of the tectorial membrane and the shearing effect
What sounds are outer hair cells excited by?
Soft sounds
How do outer hair cells mimic noises?
The prestin responds to the sound and the outer hair cell recreates the sound amplifying the sound.
What sounds do inner hair cells respond to?
Loud sounds, the quiet sounds to not create enough movement in the membrane to excite the inner hair cells.
