Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Neuro > Neuromuscular Junction > Flashcards

Neuromuscular Junction Flashcards

(61 cards)

Start Studying
1
Q

What is synaptogenesis

A

Formation of the synapse

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

The neuromuscular junction (NMJ) comprises portions of what 3 cells

A
  1. Motor neuron
  2. Muscle fiber
  3. Schwann cell
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

True or False:

The motor nerve terminal is specialized for NT release

A

True

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

What are used for energy involved with synthesis and release of NT

A

Mitochondria

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

Where is there a high concentration of AChRs on the postsynaptic cell

A

Clustered at the top of the folds

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

Where are voltage gated Na+ channels located on the postsynaptic cell

A

In the depression of folds

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

What do the Schwann cells do for the NMJ

A

Provide insulation and nourishment

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

Where do myoblasts originate from

A

The somite

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

Where do motor axons arise from

A

Somata

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

Where do Schwann cells arise from

A

Neural crest cells

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

True or False:

Neural crest cells are the precursor to Schwann cells

A

True

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

What do myoblasts turn into

A

Muscle fibers

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

Do myoblasts, motor axons, and Schwann cells travel short or long distances to create the NMJ

A

Long distance

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

True or False:

Early connections are none specific and go through a period of differentiation

A

True

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

True or False:

At birth the NMJ is fully functional and multiply innervated

A

True

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

Where do motor axons originate from

A

Neural tube

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

What do myoblasts turn into before muscle fibers

A

Myotubes

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

What does nerve to muscle contact lead to (2)

A
  1. Early synaptic transmission

2. Postsynpatic membrane differentiation

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

When do vesicles start to form in the presynaptic cell

A

As soon as the presynaptic cell touches the motor end plate

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

True or False:

AChRs subunits are expressed at low levels in myoblasts

A

True

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

Are the AChRs subunits slowly or quickly upregulated on the nerve to muscle contact

A

Quickly

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

What are the 3 way AChRs subunits are quickly upregulated

A
  1. AChR clustering
  2. Transcriptional activation of AChR subunit genes by sub-synaptic nuclei
  3. Transcriptional repression of AChR subunit genes by non-synpatic myonuclei
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What are the 3 pathways that are implicated in the process of postsynaptic differentiation

A
  1. Agrin interacts with MuSK
  2. Neuregulin interacts with erbB kinases
  3. Activation of AChRs which stimulates voltage gated channels allowing for Ca++ to enter the cell
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What does agrin interacting with MuSK do

A

Organize rapsyn mediated clustering

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
What does neuregulin interacting with erbB kinases do
Induce expression of AChR subunit genes in subsynaptic nuclei and eventually upregulate AChR
26
What does stimulation of voltage gated channels allowing more Ca++ to enter the cell do
Leads to repression of AChR expression in extrasynaptic nuclei
27
What happens if you do not have agrin
AChRs fail to cluster in the forming NMJ
28
True or False: | Agrin is a master organizer
True
29
What does MuSK act like
A second messenger the joins and phosphorylates interacting with rapsin
30
True or False: | Rapsin is an anchoring protein
True
31
How does the Ca/CAM system effect AChRs formation
Causes repression
32
What do the AChRs do in early embryogenesis and when does this occur
Cluster forming a plaque (17 days in embryo)
33
What happens to the plaque as the AChR density increase and when does this occur
The borders sharpen and length decreases (0 days postnatal)
34
What happens to the plaque postnataly and when does this occur
It perforates to form a pretzel like structure (5-30 days postnataly)
35
How do the junctional folds run in relation to each other
Parallel
36
How are the junctional folds spaced out in relation to one each other
Equally spaced
37
How do the junctional folds run in relation to the muscle fibers
Orthogonal or at right angles
38
True or False: | AChRs are densely positioned at the rest of the folds closely opposed by ACh active zones
True
39
What do the voltage gated Na+ channels do in the valleys of the junctional folds
Amplify synaptic current
40
How do the voltage gated Na+ channels amplify synaptic current
By lowering the threshold for an AP
41
What is the function of the basal lamina
It is an anchoring structure
42
Do junctional folds occur quickly or over weeks or months
Over weeks or months
43
When does transmission start to occur
When the growth cone contacts the myotube
44
What do the junctional folds help with
Stregnthening the connection and making the NMJ functional
45
What is one function of MuSK
Initiate the process of rapsyn anchoring AChRs to the membrane
46
What does rapsyn allow for
AChRs to be directly under an active zone
47
How are muscle fibers innervated at birth
Multiply innervated
48
How long does it take synaptic terminals to begin to segregate
Days
49
At what point are most muscle fibers innervated by one input
2 weeks
50
Is synaptic elimination a stereotyped response
Nope
51
What synapses are subject to elimination
Only those that fire an action potential
52
True or False: | Synapse elimination is competitive and depends on the activity of neighboring synapses
True
53
What are the 3 ways synaptic elimination occurs
1. Synaptomedian model 2. Synaptotrophin model 3. Synaptotoxin model
54
What is the synaptomedian model
Retrograde signaling may differentially reward or punish competing axons
55
What is the synaptotrophin model
Decrease in trophic factors necessary to maintain synapse
56
What is the synaptotoxin model
Damaging toxins destabilize the nerve terminal thus leading to retraction of losing input
57
What is BDNF important for
Maintenance of synapse
58
What happens if there is less BDNF
The axon retracts
59
What may agrin function as in the synaptotoxin model
Protease inhibitor
60
What is agrin responsible for at the motor terminal
Forming and inhibiting axons
61
What contacts the muscle fiber first Schwann cell, motor axon, or myoblasts
Motor axon

Neuro (15 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions