Motor Systems Flashcards

1
Q

What is the fundamental loop in all movements?

A

Sensing -> decision making -> muscle activation -> force production -> motion -> sensing

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2
Q

What is another name for muscle cells?

A

Fibres

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3
Q

What is the plasma membrane of a muscle cell called?

A

Sarcolemma

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4
Q

What are myofibrils?

A

Organelles of muscle fibres

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5
Q

What structure contains many muscle fibres?

A

Fascicle

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6
Q

What connects a skeletal muscle to bone?

A

Tendon

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7
Q

Where in a muscle cell are myofilaments found?

A

Myofibril

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8
Q

What are the myofilaments?

A

Thin actin and thick myosin

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9
Q

What structural change happens when a muscle contracts?

A

Z-discs are brought closer together

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10
Q

What is the sarcoplasmic reticulum?

A

Endoplasmic reticulum of muscle fibres

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11
Q

What is between the T tubule and sarcoplasmic reticulum?

A

Voltage-gated Ca2+ channel

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12
Q

What are the three key mechanisms for modulating muscle dynamics?

A

Adjust calcium release/uptake, change ATP production, change how effectively myosin hydrolyses/binds to ATP

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13
Q

What is an isometric muscle contraction?

A

Force = load (no movement)

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14
Q

What is a concentric muscle contraction?

A

Force > load (muscle shortening)

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15
Q

What is an eccentric muscle contraction?

A

Force < load (muscle lengthening)

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16
Q

What are the upper motor inputs?

A

Basal ganglia and cerebellum

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17
Q

What are the descending systems?

A

Motor cortex, brain stem

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18
Q

What are local circuit neurones responsible for?

A

Reflex coordination

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19
Q

What are motor neurone pools responsible for?

A

Lower motor neurones -> skeletal muscles

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20
Q

What are alpha motor neurones?

A

Lower motor neurones

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21
Q

Where is the soma of alpha motor neurones?

A

Ventral horn

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22
Q

What do alpha motor neurones innervate?

A

Muscle, with intermediate synapses

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23
Q

What is a motor unit?

A

One alpha motor neurone and all the muscle fibres innervated by it

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24
Q

What is interesting about fibres within one motor unit?

A

They are all the same fibre type

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25
Q

What are the properties of a fast-twitch muscle fibre?

A

High force and fast fatiguing

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26
Q

What are the properties of slow-twitch muscle fibres?

A

Low force, slow fatiguing

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27
Q

What are type 1 muscle fibres?

A

Slow oxidative

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28
Q

Which muscle fibre type is oxidative and has high myoglobin?

A

Type 1

29
Q

What are type 2A muscle fibres?

A

Fast oxidative glycolytic (intermediate)

30
Q

What are type 2X muscle fibres?

A

Fast glycolytic

31
Q

Which muscle fibre type is glycolytic and has low myoglobin?

A

Type 2X

32
Q

How does stimulation rate affect contraction force?

A

Increased force with increased stimulation rate

33
Q

What are the two types of summation?

A

Temporal and spatial

34
Q

How are muscles inhbited?

A

Glycinergic inhibition of innervating motor neurones in spine

35
Q

What neurones are involved in spinal reflexes?

A

Alpha motor and local circuit neurones

36
Q

What are intrafusal fibres?

A

Fibres within the muscle spindle

37
Q

What are the two types of intrafusal fibres?

A

Nuclear bag and nuclear chain

38
Q

hat are the two ending types of intrafusal fibres?

A

Annulospiral and flower spray

39
Q

What are gamma moor neurones?

A

Afferent neurones attached to muscle spindles

40
Q

What are the sensory organs of muscles?

A

Muscle spindles

41
Q

Which fibres do alpha motor neurones synapse with?

A

Extrafusal fibres

42
Q

Where are the cell bodies of sensory neurones?

A

Dorsal root ganglia

43
Q

Where are the cell bodies of motor neurones?

A

Ventral horn

44
Q

What are Ia fibres sensitive to?

A

Phasic rate of change in length

45
Q

What are II fibres sensitive to?

A

Change in length

46
Q

Which afferents are primarily nuclear bag fibres?

A

Ia afferents

47
Q

Which afferents are primarily nuclear chain fibres?

A

II afferents

48
Q

What is controlled by gamma efferents?

A

Sensitivity via stimulation of intrafusal fibres

49
Q

How fast is the myotatic reflex?

A

~30ms

50
Q

What happens in the myotatic reflex?

A

Monosynaptic activation of extensor, interneurone-mediated inhibition of flexor

51
Q

Where are Ib afferents located?

A

Within tendons

52
Q

What happens in the clasp knife reflex?

A

Activation of tricep Golgi tendon organs, inhibition of bicep

53
Q

Where are Golgi tendon organs located?

A

In tendons at the end of the muscle

54
Q

What is the sensory input of the crossed extensor reflex?

A

Delta sensory fibres via DRG

55
Q

What action is caused by the crossed extensor reflex?

A

Stepping away from something causing the foot pain

56
Q

What type of reflexes can be produced with interneurones?

A

Complex stereotyped

57
Q

How do leeches swim?

A

Sequential contraction and relaxation of body wall muscles

58
Q

What is the step cycle?

A

Leg flexion/extension, swing/stance

59
Q

What was observed when connection between brain and legs was prevented in a cat?

A

Hind legs could walk on a treadmill through reflexes alone

60
Q

Why does restoring movement in paraplegic patients rely entirely on monosynaptic contacts?

A

There is no surgical access to the ventral root where motor neurones can be stimulated

61
Q

What does the basal ganglia control?

A

Initiation of movement

62
Q

What disease is associated with hyper-inhibition of basal ganglia?

A

Parkinson’s

63
Q

What disease is associated with hypo-inhibition of basal ganglia?

A

Huntington’s

64
Q

What part of the brain controls movement?

A

Cerebral cortex

65
Q

What is the cerebellum responsible for?

A

Sensory-motor coordination and integration

66
Q

What information is compared in the cerebellum?

A

Intentional cortex actions, actual peripheral actions

67
Q

What does cerebellar hypoplasia cause?

A

Difficulty in controlling movements and posture, no feedback (only feedforward)

68
Q

What do the basal ganglia and cerebellum modulate?

A

Locomotor commands

69
Q

How is locomotion brought about?

A

Central pattern generators, no brain input