Brainscape's Knowledge GenomeTM

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


See full index

Year 2 LCRS Neurology > Neuromuscular Junction + Spinal Chord > Flashcards

Neuromuscular Junction + Spinal Chord Flashcards

1
Q

What is EPSP?

A

It is an exitatory post synaptic potential

–> potential that makes membrane less negative (lower threshold for fiering)

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

What is IPSP?

A

It is an inhibitory post synaptic potential

–> potential that makes membrane more negative (higher threshold for fiering)

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

How do you call process of graded effects that occur at a post-synaptical membrane that determine the response?

A

Summation

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

What is an alpha-motorneuron?

A

The lower motor neuron of the brainstem and spinal chord

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

What/where does an alpha-motor neuron innervate?

What is the consequence?

A

They innervate the extrafusal (outside a muscle fibre) skeletal muscle

–> cause muscle contraction

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

What is the motor neuron pool?

A

It contains all motor neurons that innervate one single, specific muslce

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

How are the alpha motor neuron pools organised in the ventral horn of a spinal chord?

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

Where are extensor and flexor motor neuron pools located in the ventral horn of the spinal chord?

A

Flexors are located more dorsally

Extensors are located more ventrally

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

What is a motor unit?

A

The unit of a single motor neuron and all muslce fibres it innervates

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

What is the smallest functional unit to produce force?

A

It is the motor unit

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

How many muscle fibres does an average motor neuron innervate in a motor unit?

A

About 600

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

Name the three types of muscle units

A
  1. S (Type I), slow
  2. FR (Type IIA), Fast, Fatigue resistant
  3. FF (Type IIB), Fast, Fatiguable
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are the propoerties of a Type I Motor unit?

A

It has slow conduction due to

  • low diameter in cell body, axon
  • small dendritic trees

–> slow twith, low tension but fatigue resistant

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

What are the properties of a Type IIA muscle unit?

A

FR –> Fast, Fatigue resistant

  1. larger cell body diameter, axonal diameter
  2. larger dendritic trees

–> Fast twitch, moderate tension, resistance to fatigue

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

What are the propoerties of a Type IIB motor unit?

A

FF –> Fast, fatigueable

  1. Larger diameter, larger dentritic trees

–> Fast twitch, high force, high fatigue

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

What are the two mechanisms by which force of muscle contraction it regulated?

A
  1. Recruitement
    • targeted selection of motor neurons needed
  2. Rate coding
    • the rate of AP fiering –> the higher the rate, the higher the force
17
Q

Explain the concept of muscle unit recruitment

A

Done via the “size principle”

  • smaller units are requruited first (normalls T1 units)
  • As more force is required, more units are recruited

–> Allows fine tuning for low-force movements (e.g. writing)

18
Q

Explain the concept of Rate coding in muscle force regulation

A

As the firing rate increases, the force produced by the unit increases

–> higher fiering rate= higher force

19
Q

Which changes do muslce fibres undergo during training?

A

There is a shift from TIIB to TIIA –> Fatiguable to Fatigue resistant

20
Q

What are the associated changes in muscle fibres with ageing?

A

Ageing is associated with both: loss of TI+II but more commonly TII

–> leading to slower muscle contraciton

21
Q

The corticospinal tracts in the spinal chord controll voluntary movement. What is collective name of tractrs that modulate/controll involuntary movements ?

A

They are collectively known as extrapyramidal tracts e.g.

  1. Rubrospinal tracts
  2. Vestibulospinal tract etc. for balance reflex, maintaining posture etc.
22
Q

What is the function of the extrapyramidal tracts?

A

Modulate involuntary movement via:

Automatic movements in responst to posture, balance changes, painful stimmuli etc.

23
Q

What is a reflex?

A

An automatic response to an external stimulus without involvement of conciousness (no brain involved)

An involuntary coordinated pattern of muscle contraction and relaxation elicited by peripheral stimuli.

24
Q

What are the componenets of a reflex?

A
25
Q

What is a monosynaptic reflex?

A

A simple relex response with a single synapse between afferent and efferent pathways

–> Simple stretch responses: e.g. knee jerk etc.

26
Q

What is a polysynaptic reflex?

A

A reflex that involved two or more synapses in the spinal chord, involves more muscles at different levels

–> Complex reflexes e.g. withdraw from sharp objects–> also involves balance, weight change onto other leg to maintain balance etc.

27
Q

What is supraspinal control of reflexes?

A

Reflexes can be controlled by higher centres of the CNS

  1. Normally inhibitory Rigidity and spasticity can result from brain damage giving over-active or tonic stretch reflex
28
Q

Through which ways can supraspinal reflex control be achieved?

A

Higher centres influence reflexes by:

  1. Activating alpha motor neurons
  2. Activating inhibitory interneurons
  3. Activating propriospinal neurons
  4. Activating gamma motor neurons
  5. Activating terminals of afferent fibres
29
Q

What is intrafusal innervation of muscle fibres?

A

Innervation within the muslce cells consisting of

  1. Gamma motor neurons
  2. sensory axons
30
Q

What are the characteristics and function of gamma motor neurons?

A

They innervate the muscle intrafusally

–> respond intracellularly to muscle movement

31
Q

Name examples of centres that are involved in higher controll of reflexes

A
  1. Cortex – corticospinal (fine control of limb movements, body adjustments)
  2. Red nucleus – rubrospinal (automatic movements of arm in response to posture/balance changes)
  3. Vestibular nuclei – vestibulospinal (altering posture to maintain balance)
  4. Tectum – tectospinal (head movements in response to visual information).
32
Q

What is the difference between an intrafusal and extrafusal muscle fibre?

A

Intrafusal = skeletal muscle fibres that serve as sensory organs/proprioceptors which detect the amount and rate of change of the length of a muscle

Extrafusal = standard skeletal muscle fibres which are innervated by alpha motor neurones

33
Q

What are signs and symptoms for a upper motor neuron lesion?

A
  • HYPERREFLEXIA
  • CLONUS
  • BABINSKI’S SIGN
34
Q

Explain the structure of a NMJ

A

It is just a specialised Synapse

  1. AP arrives
  2. Ca2+ influx
  3. Vesicle exocitosis
  4. Release of Ach
  5. Binds to recetors on Motor end plate
  6. Cause Ion channel opening an Ca2+ influx
  7. AP in mucle fibres
35
Q

What are neurotrophic factors?

A

Are a type of growth factor

  • Prevent neuronal death
  • Promote growth of neurons after injury
36
Q

What are the effects of neurotrophic factors on a motorunit?

A

They affect the function of the muscle fibres (by changing the innerveating nerve)

37
Q

What are pyramidal tracts?

A

Connection of the motor cortex with the periphery (spinal chord) –>

  • corticospinal tracts (lateral and anterior)
    • Fine, precise movements
38
Q

What are the extra-pyramidal tracts?

A

Connecting different parts of the CNS (includieg Cortex but also Cerebellum etc.) to periphery

  • Mainly involved in gross, movement of proyimal muscles
    *
39
Q

What is the exact order in which different motor fibres are recruited?

A

Slow, fast fatigue resistant, fast fatigable

Year 2 LCRS Neurology (20 decks)

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