Brainscape's Knowledge GenomeTM

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


See full index

Neuro > Neuromuscular Junction > Flashcards

Neuromuscular Junction Flashcards

1
Q

What is goal directed motor control

A

Conscious, explicit, controlled

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

What is habit motor control

A

Unconscious, implicit, automatic

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

Define antagonistic arrangement

A

Combined co-ordinated action

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

Define recruitment of muscle fibres

A

Fast/slow twitch

Smaller or larger motor units

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

What is the activation of muscle fibres

A

All or none

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

What is the order of muscles

A

Myofibrils contain protein filaments - actin and myosin

Muscle fibres constituted of several myofibrils

Muscle fasciculus compromises of several muscle fibres

Skeletal muscle compromises of several muscle fasciculi

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

Define a motor unit

A

Single alpha motor neuron + all muscle fibres it innervates

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

Motor unit

How many muscle fibres do motor neurones innervate

A

Different motor neurones innervate different numbers of muscle fibres

Fewer fibres = greater movement resolution e.g. innervating the finger tips and tongue

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

Describe the role of the motor unit

A

Final common pathway for motor control

Action of an alpha motor neuron depolarises and causes contraction of all muscle fibres in that unit (all or none)

Muscle fibres innervated by each unit are the same type and often distributed through the muscle to provide evenly distributed force - may help reduce effect of damage

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

What happens if more motor units fire

A

More fibres contract = more power

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

What does the number of muscle fibres innervated by a single motor unit vary according to

A

Level of control

Strength

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

Motor unit what is the size principle

A

Units are typically recruited order of size (smallest first(

Fine control typically required at lower forces

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

What needs to be known by the CNS for control of muscles

A
  1. tension on the muscle - golgi tendons
  2. length (stretch) on the muscle - muscle spindles
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What detect tension on a muscle

A

Golgi tendon

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

What detect stretch on a muscle

A

Muscle spindles

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

Where are golgi tendon organs found

A

Within tendons

17
Q

What is the role of the tendon golgi apparatus

A

Sends sensory information to the brain via the spinal cord about how much force there is on a muscle

18
Q

What is the tendon golgi apparatus critical for

A

Proprioception

19
Q

What can the tendon golgi apparatus do under extreme conditions

A

Act to inhibit muscle fibres - via the circuit in the spinal cord - to prevent damage

20
Q

What are muscle spindles key in

A

Reflex circuits

21
Q

Define reflexes

A

Can be quite simple or complex. They can operate without engagement with the brain, and are critical for avoidance of injury and effective motor control

22
Q

What is the role of intrafusal fibres in stretch reflex

A

Need to detect stretch regardless of the current muscle length

Intrafusal fibres are innervated (gamma motor neurones) separately to extrafusal fibres

They keep intrafusal fibres set at a length that optimises muscle stretch detection

23
Q

Describe the stretch reflex

A

5 components

  1. receptor - muscle spindle
  2. afferent fibre - muscle spindle afferent
  3. integration centre - lamina IX of spinal cord
  4. efferent fibre - a-motor neurones
  5. effector - muscle

e.g. holding a cup of tea

24
Q

Describe muscle spindle feedback

A

Sensory fibres (muscle spindles) are coiled around intrafusal fibres

25
Q

Describe the withdrawal reflex

A
  1. noxious stimuli
  2. afferent fibre to dorsal horn of spinal cord
  3. synapse within the spinal cord
  4. leave via ventral horn. will supply excitatory input to ipsilateral flexor muscle group. Extensor inhibitory - reciprocal inhibition (opposite happens for the other foot)
  5. limb moves away within half a second

e.g. standing on a pin pulling foot away

26
Q

What are the symptoms of an upper motor neuron lesion

A

Disuse atrophy (minimal) or contractures - muscle wasting

Increase tone (spasticity/rigidity)

Pyramidal weakness

Hyperreflexia

Babinski sign

LMN do not know to stop

27
Q

What are the symptoms of lower motor neuron lesions

A

Marked atrophy

Reduced one

Variable patterns of weakness

Reduced or absent weakness

No Babinski sign

28
Q

What lesion shows a positive Babinski sign

A

Upper motor neuron

29
Q

What is a positive Babinski sign

A

Occurs when stimulation of lateral plantar aspect of the foot leads to extension (dorsiflexion or upward movement) of the big toe

Neuro (15 decks)

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