Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Anatomy and Physiology > Active (micro) mechanics and signal transduction > Flashcards

Active (micro) mechanics and signal transduction Flashcards

OHC Mechanics / Hair Cell Signal Transduction / Neuron Action Potentials

1
Q

Review of macromechanics: What did Selleck’s studies show us?

A

resolving power of fine tuning of the BM

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Review of macromechanics: What are the sources of non-linearity?

A

system amplifies low level stimuli; doesnt do this with high level stimuli

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

OHCs are thought of as _________________ driven by a physiological motor

A

mechanical vibrator

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Electrical stimulation of hair cells showed that they were capable of _________ in response to a depolarizing stimulus and _________ in response to a hyperpolarizing stimulus

A

contracting; elongating

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

depolarize makes the cells _________

A

shorter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

hyperpolarize makes the cells _________

A

taller

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

OHCs help explain the resolving power in the cochlea and how it distinguishes between ____ Hz to _____ Hz

A

1000 Hz to 1001 Hz

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what are the obvious possible source of OHC

A

Olivocochlear bundles (OCB)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

diagram: source of OHC control

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

how would it work? think about __________

A

waves

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

when the two waves are perfectly in phase with one another, their signals _______ each other

A

augment; add

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

when the two waves are slightly out of phase with one another, the overall signal is _________ (results in ___________ interference)

A

dimished; destructive interference

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

when the phase shift between them reach 180 degrees, the two waves _________ each other

A

cancel

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

the result of this type of motion is a ___________

A

resonance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

resonance can facilitate vibration of the BM, enhancing _________ at a specific location along the BM

A

frequency selectivity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

resonance ________ desired vibration and will actually _________, by cancellation, the vibration of the adjacent areas of the BM

A

amplifies; reduce

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

OHC exhibit a gradient in high from base to apex: ________ um tall at the base and _________ um tall at the apex

A

<15 um and >90 um

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

OHC ______ when hyperpolarized and ____________ when depolarized

A

elongate; shorten

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

the lateral wall of OHC is specialized as a _____________ structure

A

trilaminate structure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

what does the trilaminate structure consist of?

A

1) wrinkled plasma membrane (outermost)
2) subsurface cisternae (innermost, ER like)
3) intervening extra-cisternal space

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

radially orientally pillars connect the plasma membrane to a cortical _________ network

A

actin network

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

what is actin network arranged as and what is it cross-linked by

A

arranged as circumferentially orientated parallel fibers and cross linked by spectrin; creating flexible scaffolding

23
Q

diagram of OHC with lateral wall components

A
24
Q

The ________ is found within the lateral wall plasma of OHC

A

motor

25
Q

_________ likely serves as the motor

A

Prestin

26
Q

What is Prestin found to convey?

A

electromotility to transfected cells

27
Q

why is Prestin unique? list 2 reasons

A

1) does not require ATP hydrolysis for energy
- directly on membrane potential
- uses electrical energy directly
2) does not require Ca 2+ for activation

28
Q

Prestin works _________ than any other biological force generator

A

faster

29
Q

Prestin works by binding and shuttling intraceullar anions (Cl - chloride) ______ the extracellular surface

A

toward

30
Q

When does this binding and shuttling of intracellular anions toward the extracellular surface take place?

A

following hyperpolarization

31
Q

When does this binding and shuttling of intracellular anions toward the intracellular surface take place?

A

depolarization

32
Q

Prestin also works by binding and shuttling intraceullar anions (Cl - chloride toward the _________ surface

A

intracellular

33
Q

electrical signals (those Prestin relies on) are probably derived from OHC stimulation, with input from the __________ fibers that innervate the OHCs

A

efferent (OCB) fibers

34
Q

what are the functional significances of OHCs? (3)

A

a) cochlear amplifier
b) equalization
c) tone-on-tone suppression

35
Q

the cochlear amplifier can __________ sound levels

A

increase

36
Q

cochlea amplifier increases sound levels up to 1000 fold at lowest sound levels and decreases with ____________ stimulus intensity

A

intensity

37
Q

allows the perception of 2 sufficiently diff frequencies within a stimulus, indepdent of their intensity

A

equalization

38
Q

equivalent to lateral inhibition seen in eye and other neural structures (allowing for even sharper tuning of BM)

A

tone on tone suppression

39
Q

what is another term for tone on tone suppression

A

frequency masking

40
Q

what is frequency masking

A

process inhibits neighboring or adjacent regions (frequencies) to highlight the most prominent

41
Q

what exactly is the frequency masking

A

fine tunes/suppress/cancels adjacent vibrations of regions
- 2 similar tones may mask one another

42
Q

all receptor cells, regardless of receptive field, work as _________ to convert some form of physical or chemical energy to a form that can be conveyed by a neuron to CNS

A

signal transducers

43
Q

because of the speech with which ions start to flow into the sensory hair cell following deflection of stereocilia, it has been assumed that the mechanism responsible must rely on mechanical control of the ________

A

gating mechanism

44
Q

tip links of the gating mechanism: what are they?

A

strands of extracellular glycoprotein
- Cadherin-23
- Protocadherin-15

45
Q

the tip link extends from _____ of one stereocilia to the ________ of an adjacent
taller stereocilia

A

tip; side

46
Q

tip link is most likely somehow inserted into a ___________

A

mechanically gated ion channel (MET)

47
Q

what does the MET allow?

A

change in membrane potential
- K+ ions into cell

48
Q

gating mechanism drawing

A
49
Q

what other component of sensory mechanotransduction machinery have been identified? (3)

A

tetraspan membrane protein in hair cell stereocilia (TMHS)
transmembrane inner ear
(TMIE)
transmembrane channel-like proteins 1 and 2
(TMC1/2)

50
Q

Deflection of the hair bundle toward the tallest stereocilia leads to an ______ in the probability of MET channel opening, while deflection in the opposite direction _______ channel open probability.

A

increase; decrease

51
Q

what could impact MET channel opening?

A
  • deflection of hair bundles
  • changes in OHC height
  • MET channel is nonselective for cations, but increased activity when external calcium is decreased (like endolymph)
52
Q

signal transduction summary

A

1) Fluid forces elicit traveling waves along BM
2) Shearing force causes stereocilia deflection
3) Tip links become taut
4) MET channels open
5) Nonselective cation flow (K+ ions into hair cell)
6) hair cell depolarization
7) Voltage gated Ca+ channels open
8 Ca+ neurotransmitter vesicles move to BM & fuse releasing glutamate into synaptic cleft shared with SGN
9) Receptors on afferent nerve bint NT → SGN produce 1st AP

53
Q

what other mechanisms could be at play with signal transduction?

A
  • other ion channels/complexes
  • additional channels that fine tune calcium-initiated vescile response + promote repolarization
  • mechanisms of adaptation of the MET channel
  • how OHC motility affects probability of MET channel opening
    (all must be further researched)

Anatomy and Physiology (17 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions