Hair Cells

Question 1

What is the shape of the outer hair cells?

Answer 1

cylindrical

Question 2

Which cells are jug like in shape?

Answer 2

Inner hair cells

Question 3

What do inner hair cells have more of than outer hair cells?

Answer 3

Mitochondria and motor proteins

Question 4

In what shape are the inner hair cells arranged?

Answer 4

A slight curved shape

Question 5

In what shape are the outer hair cells arranged?

Answer 5

A sharpe ‘M’ shape

Question 6

Are the inner hair cells placed over the basilar membrane?

Answer 6

Not always, they can also be placed on the osseous spiral lamina

Question 7

Are the outer hair cells placed over the basilar membrane?

Answer 7

Yes, always

Question 8

What is another (technically incorrect) name for a hair cell?

Answer 8

cilia

Question 9

What are the tallest cilia called?

Answer 9

Sterocilia

Question 10

What is the lid on the organ of corti called?

Answer 10

Tectorial Membrane

Question 11

How does the membrane move?

Answer 11

In a sharing affect

Question 12

What hairs are impacted by this movement?

Answer 12

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

Question 13

How do afferent nerve fibres work?

Answer 13

They send messages from the periphery to the central nervous system

Question 14

How do efferent nerve fibres work?

Answer 14

They send messages from the brain to the periphery an are almost always inhibitory. They can only say stop or turn off

Question 15

How many afferent nerve fibres connect to the inner hair cells?

Answer 15

10,000-20,000

Question 16

How many afferent nerve fibres connect to the outer hair cells?

Answer 16

15,000-20,000 and they are shred between 3-5 hair cells

Question 17

How do efferent nerve fibres connect to the hair cells?

Answer 17

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.

Question 18

What is Mechano-Electrical Transduction?

Answer 18

It is the transfer of energy from mechanical to electrical.

Question 19

How does Mechano-Electrical Transduction work?

Answer 19

Hair fibres turn the mechanical energy into electrical messages by exciting the nerves through the tip links in the hair cells.

Question 20

What are tip links?

Answer 20

Tip links are where the shorter hair cells connect to the taller hair cells.

Question 21

What is the Trap Door Theory?

Answer 21

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.

Question 22

What is Prestin?

Answer 22

Prestin is a special motor protein called Piezoelectric and changes shape with a change in voltage

Question 23

What is the Theory of Prestin?

Answer 23

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.

Question 24

What is the main function of outer hair cells?

Answer 24

They amplify sounds

Question 25

What is the risk that outer hair cells face?

Answer 25

Damage with loud noise due to the vibration of the tectorial membrane and the shearing effect

Question 26

What sounds are outer hair cells excited by?

Answer 26

Soft sounds

Question 27

How do outer hair cells mimic noises?

Answer 27

The prestin responds to the sound and the outer hair cell recreates the sound amplifying the sound.

Question 28

What sounds do inner hair cells respond to?

Answer 28

Loud sounds, the quiet sounds to not create enough movement in the membrane to excite the inner hair cells.