~Chapter 11 - Lecture Section 11.2

Question 1

What are the parts of the Outer Ear?

Answer 1

The Pinnae, the Auditory Canal, and the Tympanic Membrane (eardrum)

Question 2

What are the parts of the Middle Ear?

Answer 2

The Ossicles, the Oval Window, and the Middle Ear Muscles

Question 3

What are the parts of the Inner Ear?

Answer 3

The Cochlea

Question 4

Which part of the Ear holds up our glasses?

Answer 4

The Pinnae

Question 5

The shape of the ___ is important for sound localization

Answer 5

Pinnae

Question 6

Does the Pinnae play a role in transduction?

Answer 6

Not a large one, no

Question 7

True or False: The length of the Auditory Canal is important

Answer 7

True

Question 8

The sound waves that are reflected off of your ___ create ___ interference with incoming waves, such that sound in the range of ___Hz is amplified.

Answer 8

eardrum (the Tympanic Membrane) // constructive // 2,000-5,000

Question 9

Where is the Tympanic Membrane (Eardrum) located?

Answer 9

At the very end of the Auditory Canal

Question 10

Which part of the Ear serves as the border between the Outer and Middle Ear?

Answer 10

The Tympanic Membrane (Eardrum)

Question 11

The Middle Ear consists of an ___ and ___ structures.

Answer 11

air-filled chamber // amplification

Question 12

What are the Ossicles?

Answer 12

Malleus (Hammer), Incus (Anvil), Stapes (Stirrup)

Question 13

Where are the smallest bones in the human body located?

Answer 13

In the Middle Ear. They are the Malleus (Hammer), Incus (Anvil), and Stapes (Stirrup)

Question 14

The ___ connect the Tympanic Membrane to the ___.

Answer 14

Ossicles // Cochlea

Question 15

How were the Ossicles named?

Answer 15

They are named after their shape

Question 16

What is the job of the Ossicles?

Answer 16

Their job is to amplify sound-waves

Question 17

The Ossicles are associated with the ___.

Answer 17

Middle Ear Muscles

Question 18

Where are the smallest skeletal muscles in the human body located?

Answer 18

In the Middle Ear, they are the Middle Ear Muscles

Question 19

What is the job of the Middle Ear Muscles?

Answer 19

Their job is to dampen vibration at the Ossicles at high intensities

Question 20

As sound-waves are pressing onto the Tympanic Membrane, there is vibration that is transmitted through the Ossicles, and it pushes onto the ___ of the Cochlea.

Answer 20

Oval Window

Question 21

The ___ is filled with fluid, so it cannot compress, and so whenever the ___ pushes in on the ___, the ___ pops out.

Answer 21

Cochlea // Stapes // Oval Window // Round Window

Question 22

There are ___ ways that the Ossicles cause physical amplification in the Middle Ear

Answer 22

2

Question 23

What is the first way that the Ossicles cause physical amplification in the Middle Ear?

Answer 23

The Tympanic Membrane has a much larger surface area than the surface area of the Stapes foot plate, therefore the Ossicles concentrate the vibration onto a much smaller surface area which increases the sound-pressure level by a factor of 17.

Question 24

What is the second way that the Ossicles cause physical amplification in the Middle Ear?

Answer 24

By acting as levers, a bit like a teeter totter, and this increases vibration by a factor of 1.3P

Question 25

Why is Physical amplification of sound by the Middle Ear required?

Answer 25

Because pressure changes in the air (Outer and Middle ear) are transmitted poorly to liquid (the Cochlear fluid) and so it requires amplification in order to make those sound vibrations large enough to produce Transduction.

Question 26

Why do some fish not have Outer and Middle Ear structures?

Answer 26

Because they do not need to amplify sounds as greatly since water and Cochlear fluid have similar densities, both the Outer and Inner areas are both fluid-filled.

Question 27

When you listen to sound underwater, that dampening is what’s being overcome by the amplification in the ___.

Answer 27

Middle Ear

Question 28

What are the physical characteristics of the Cochlea?

Answer 28

In its natural state, the Cochlea is a spiral-shape. The Cochlea is about 2mm x 35mm

Question 29

Pressure changes produced by the movement of the Stapes creates vibrations that are transmitted to the fluid, and so the ___ that are impinging on the Tympanic Membrane through the amplification by the Ossicles, and this spiral-nature of the Cochlea set up ___ in the ___.

Answer 29

longitudinal waves // transverse waves // Basilar Membrane

Question 30

Is the Cochlea an air-filled or fluid-filled structure?

Answer 30

Fluid-filled structure

Question 31

The Cochlea is split into two parts by the ___.

Answer 31

Cochlear Partition

Question 32

What is the Scala Vestibuli?

Answer 32

The top part of the Cochlea

Question 33

In the Scala Vestibuli, the top part, which is connected to the ___ and ___, extends from the ___ at the Cochlea’s Base to the Apex.

Answer 33

Stapes // Oval Window // Oval window

Question 34

What is the Scala Tympani?

Answer 34

The bottom part of the Cochlea

Question 35

The Scala Tympani is the part that extends from the Apex to the ___ at the Cochlea’s base

Answer 35

Round Window

Question 36

Where is the Basilar Membrane located?

Answer 36

Within the Scala Tympani

Question 37

At the Apex of the Cochlea, there is an opening where the fluid pressure that increases at the ___, is transmitted through to the ___.

Answer 37

Scala Vestibuli // Scala Tympani

Question 38

Where is the Organ of Corti located?

Answer 38

The Organ of Corti is located in the Cochlea, and sits on the bottom of the Basilar Membrane in the Scala Media

Question 39

What is the Scala Media?

Answer 39

The Scala Media is a fluid canal that sits in between the Vestibuli and Tympani

Question 40

Where is the site of sound transduction into neural activity?

Answer 40

The Organ of Corti

Question 41

The Organ of Corti consists of hair-cells, there is a ___ row of Inner hair cells and ___ row(s) of Outer hair cells. A gelatinous ___ sits and flops and touches all of the bristles on the hair cells.

Answer 41

single // 3 // Tectorial Membrane

Question 42

The 3 Outer rows of Cilia/Hair cells are arranged in a ___ pattern.

Answer 42

Chevron

Question 43

There are ___ Inner hair cells and ___ Outer hair cells

Answer 43

3,500 // 12,000

Question 44

Hair cells are connected to fibers that leave the Cochlea as the ___.

Answer 44

Auditory Nerve

Question 45

The Inner hair cells send ___ inputs such that each hair cell connects to ___ Auditory Nerve Fibres.

Answer 45

diverging // 8-30

Question 46

Outer hair cells send ___ inputs to each Auditory Nerve Fiber, and each fibre is connected to many Outer hair cells.

Answer 46

converging

Question 47

All the hair cells have Cilia, and when the Cillia ___, the transduction process starts.

Answer 47

bend

Question 48

What is the transformation of longitudinal sound-waves into transverse waves of the Basilar Membrane?

Answer 48

When the Stapes vibrates, the Oval Window vibrates, this causes pressure changes in the Cochlear fluid.

Question 49

What is the Transverse wave?

Answer 49

The Basilar Membrane vibrates at the same frequency as the Stapes, up and down

Question 50

Depending on the direction the Cilia are deflected, it will produce either ___ or ___ in the hair cell.

Answer 50

Depolarization // Hyperpolarization

Question 51

Depending on the direction the Cilia are deflected, it will produce either ___ or ___ in the hair cell.

Answer 51

Depolarization // Hyperpolarization

Question 52

If the Cilia are deflected toward the long side, it produces ___.

Answer 52

Depolarization

Question 53

If the Cilia are deflected toward the short side, it produces ___.

Answer 53

Hyperpolarization

Question 54

Do hair cells fire action potentials?

Answer 54

No, the hair cells themselves do not fire action potentials

Question 55

The hair cells themselves do not fire action potentials, but the ___ that they're connected to will ___ their firing rate when the hair cells are Depolarized, and they will ___ their firing rate when the hair cells are Hyperpolarized.

Answer 55

Auditory Nerves // increase // decrease

Question 56

Each hair cell has ___ extracellular environments.

Answer 56

2

Question 57

What is the first extracellular environment of the hair cell?

Answer 57

On the top where the Cilia rest. In the Scala Media there is a fluid called Endolymph which has an extremely high K+ concentration (+80mV).

Question 58

What separates the 2 extracellular environments of the hair cell?

Answer 58

Tight junctions referred to as the Reticular Lamina which seal off the top compartment from the rest of the cell

Question 59

What is the second extracellular environment of the hair cell?

Answer 59

The fluid of the Paralymph is similar to Cerebral Spinal Fluid (CSF), it has lower K+ concentration (0mV).

Question 60

Endolymph which has an extremely ___ K+ concentration of around ___.

Answer 60

high // +80mV

Question 61

Paralymph is similar to ___, it has ___ K+ concentration of ___.

Answer 61

Cerebral Spinal Fluid (CSF) // lower // 0mV

Question 62

What is one function of the very unusual structure of the two different extracellular environments of hair cells?

Answer 62

It is important for producing neural activity in the hair cells.

Question 63

What is the resting potential of an Outer hair cell?

Answer 63

-70mV

Question 64

What is the resting potential of an Inner hair cell?

Answer 64

-40mV

Question 65

___ are the mechanism of Transduction.

Answer 65

Tip Links

Question 66

How are Cilia connected to one another?

Answer 66

By Tip Links

Question 67

What are Tip Links?

Answer 67

Strands/strings that link Cilia together

Question 68

Tip Links pull on ___ that will open or close depending on the ___ of the Tip Links.

Answer 68

ion channels // tension

Question 69

Tip Link is made of a protein called ___, and this ___ strand connects two hair cell ___ channels.

Answer 69

Cadherin23 // Cadherin23 // Mechanoelectrical Transduction (hcMET)

Question 70

The ___ tension that is on the Tip Link, it will pull these hcMET channels open, and allow ions to flow.

Answer 70

more

Question 71

What is the problem with hcMET?

Answer 71

The actual identity of what these hcMET are is debated Some say it’s a TRPA1 channel, and some don't assign it an identity at all. -For our purposes, the hcMET is more of an agnostic, it's talking about its function rather than its genetic origin.

Question 72

The structure of these two channels that are linked by this strand create a ____.

Answer 72

mechanically gated ion channel

Question 73

At rest, there is a ___ tension on the Tip Links, and hcMET gates are pulled ___, and it's letting a little bit of that K+ from the ___ flow in.

Answer 73

medium // partially open // Scala Media

Question 74

When there is deflection of Cilia towards the long-side of the Stereocilia, this pulls the hcMET gates ___, allowing ___ K+ to flow in.

Answer 74

open more // more

Question 75

When there is deflection of Cilia towards the short-side, this relaxes all the Tip Links, allowing the hcMET gates to ___ fully, and it ___ any K+ from flowing in.

Answer 75

close // stops

Question 76

Ca2+ triggers ___ of neurotransmitters

Answer 76

exocytosis