Week 7 - Movement Flashcards

1
Q

What are the functions of muscles?

A

Smooth Muscles - control digestion and other organs
Skeletal or Striated muscles control movement
Cardiac muscles - control the heart

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2
Q

What is a neuromuscular junction?

A

a synapse between a motor neuron axon and a muscle fibre.

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3
Q

In skeletal muscles, every axon releases…

A

…acetylcholine at the neuromuscular junction.

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4
Q

Does acetylcholine always excite the muscle to contract?

A

Yes!

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5
Q

What does a deficite of acetylcholine mean?

A

that will impair movement.

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6
Q

Every makes ONE movement…

A

A contraction.

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7
Q

The muscle relaxes when it receives…

A

NO message.

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8
Q

Moving an arm or leg back and forth requires opposing sets of muscles called…

A

antagonistic muscles.

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9
Q

Humans (vs. fish) have certain types of muscle fibres bound together. What are they?

A

Fast-twitch fibres and slow-twitch fibres.

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10
Q

We rely on …… for the least strenuous activities.

A

slow and intermediate fibres.

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11
Q

Slow twitch fibres do not fatigue rapidly because they are…

A

Aerobic - they use oxygen during their movements.

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12
Q

Fast-twitch fatigue rapidly because…

A

they’re Anaerobic - using reactions that do not require oxygen at the time but need oxygen for recovery. Using them builds up an oxygen debt!

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13
Q

What do flexor and extensor muscles do?

A

Flexor muscles are there to bring a muscle/limb in, extensors are there to pull it back.

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14
Q

What do proprioceptors do?

A

They are receptors that detect the position or movement of a part of the body.

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15
Q

What do muscle proprioceptors do?

A

detect the STRETCH and TENSION of a muscle and send messages that enable the spinal cord to adjust its signals. When a muscle is stretched, the spinal cord sends a signal to contract it reflexively.

This STRETCH REFLEX is CAUSED by a stretch, it does not PRODUCE one.

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16
Q

What is a muscle spindle?

A

a proprioceptor - a receptor parallel to the muscle that responds to a stretch. Whenever the muscle is stretched more than the antagonistic muscle, the muscle spindle sends a message to a motor neuron in the spinal cord, which in turns sends a message back to the muscle, causing a contraction.

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17
Q

When you step on a bump in the road, your knee bends a little, stretching the extensor muscles of that leg. The sensory nerves of the spindles SEND action potentials to the motor neuron in the spinal cord. THEN WHAT?

A

…then the motor neuron sends action potentials to the extensor muscle. Contracting the extensor muscle straightens the leg, adjusting for the bump on the road.

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18
Q

A tap on the knee is testing what?

A

stretch reflexes. The tap stretches the extensor muscles and their spindles, resulting in a message that jerks the lower leg upward. A leg that jerks excessively or not at all may indicate a neurological problem.

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19
Q

What are Golgi tendon organs?

A

they are also proprioceptors, and respond to increases in muscle tension. They are in tendons, acting as a brake against an excessively vigorous contraction.

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20
Q

Vigorous muscle action inhibits further contraction by…

A

activating the Golgi tendon organs.

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21
Q

What else, other than controling important reflexes, do proprioceptors do?

A

They send information to the brain.

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22
Q

Why do we perceive smaller objects that weigh the same as larger objects to weigh more?

A

Proprioceptors, baby. People think that larger means heavier, so the actual weight displaces their proprioceptors less than expected and therefore yields the perception of a lighter object.

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23
Q

What is a reflex?

A

A consistent, automatic response to stimuli. They are insensitive to reinforceres, punishments and motivations.

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24
Q

Some examples of relfexes.

A

Stretching, the constriction of the pupil in response to bright light, infant grasping with toes.

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25
Q

What are central pattern generators?

A

Neural mechanisms IN THE SPINAL CORD of excitation and inhibition that generate rhythmic patterns of motor output.

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26
Q

List some examples of central pattern generators.

A

Flapping wings, the “wet dog shake”.

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27
Q

What is a motor program?

A

A fixed sequence of movements.

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28
Q

Can a motor program be gained or lost through evolution?

A

Yes!

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29
Q

What is an example of a motor program in humans?

A

Yawning. Smiles, frowns and the raised eyebrow greeting. Hugging is NOT a built in motor program, but it is interesting to note that the average nonromantic hug lasts three seconds for people throughout the world.

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30
Q

Does the primary motor cortex send signals directly to the muscles?

A

No. Its axons extend to the brainstem and spinal cord, which generate the impulses that control the muscles.

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31
Q

Do some axons go directly from the cerebral cortex to motor neurons?

A

Yes, presumably giving us greater dexterity.

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32
Q

What is the role of the posterior parietal cortex?

A

Attention to space around us and planning a movement. The posterior parietal cortex monitors the position of the body relative to the world. It is relatively larger in humans reflecting enhanced role in selecting appropriate actions. It outputs to the PREMOTOR CORTEX.

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33
Q

What is the role of the primary somatosensory cortex?

A

Main receiving area for touch and other body information.

  • responds to shape of object and grasping, lifting or lowering.
  • contains a detailed map of the body.
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34
Q

What is the role of the prefrontal cortex?

A

Active when planning and calculating possible outcomes for a movement.

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35
Q

What is the role of the premotor cortex?

A

To prepare the body’s muscles for the exact movements it’s about to make. It helps you control your movements.

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36
Q

What is the role of the supplementary motor cortex?

A

active during preparations for a rapid series of movements; typing, dancing, speaking, playing musical instrument.

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37
Q

What is the role of the cerebral cortex?

A

Complex actions such as writing - less voluntary movements eg. coughing, laughing, crying are controlled by subcortical areas.

Motor map spans knee, hip, trunk, arm, elbow, wrist, hand, face, lips, jaw tongue etc. Parts with fine control cover more space on the cerebral cortex.

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38
Q

What is the role of the primary motor cortex?

A

Directly innervates lower motor neurones. It generates neural impulses that control the execution of movement.

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39
Q

What results in the stimulation of the posterior parietal cortex?

A

attention to the SPACE around us. Also, INTENTION to move. After more intense stimulation, people believe they did make the movement.

40
Q

What is the role of the motor cortex in movement generation?

A

Active during preparations for a movement. Receives information about target and body location.

41
Q

What happens when you have damage to prefrontal cortex?

A

Movements are badly planned. Showering with clothes on, salt in tea etc. Missing steps. Perform individual movements normally, lack ability to correct errors as you are doing movements.

42
Q

Is prefrontal cortex active or inactive during dreaming?

A

Inactive.

43
Q

What does the lateral premotor cortex do?

A

Interaction with external objects.

44
Q

What does the lateral premotor cortex do?

A

Interaction with external objects.

45
Q

What is the role of the basal ganglia?

A

Act as an on/off switch to release movements stored in the supplementary motor area.

46
Q

Supplementary motor area stores motor programs. What does the substancia nigra do?

A

Acts as a stop/go switch/signaller for these motor programs.

47
Q

What is the basal ganglia?

A

A group of large subcortical structures in the forebrain.

48
Q

What does the basal ganglia do?

A

Stores sensory information to guide movements, learn rules and organise sequences of movements into a smooth, automatic whole.

  • organise action sequence into chunks or units like learning to drive a car (habit learning).
  • increase “vigor” of movements
49
Q

What is parkinson’s disease caused by?

A

gradual progressive death of neurons in the substantia nigra.

50
Q

What does substantia nigra mean?

A

“black substance”

51
Q

Why is the substantia nigra dark in colour?

A

because it is the main source of dopamine and dopamine is quite dark.

52
Q

When do symptoms of Parkinson’s disease start showing?

A

After 20-30% of neuron death in the substantia nigra.

53
Q

Symptoms of Parkinson’s.

A

Slow on cognitive task, also unable to solve problems they could beforehand.
Difficulty releasing movements/starting physical activities.

54
Q

Possible causes of Parkinson’s.

A

Could be genetic. 5 genes common but no one specific gene. Also potential exposure to toxins.

55
Q

How is Parkinson’s treated?

A

With L-Dopa.

56
Q

What is L-Dopa?

A

Chemical precursor to dopamine. Crosses BBB. Helps in early and intermediate stages but doesn’t stop everyone. Also doesn’t stop disease from progressing.

57
Q

What are side effects of L-Dopa?

A

nausea, restlessness, hallucinatins and delusions, low blood pressure.

58
Q

Other treatment for Parkinson’s.

A

Electrical stimulation of globus pallidus.

Cell transplants of fetal brain cells.

59
Q

What is Huntington’s Disease?

A

Genetic.
Damage to caudate nucleus, putamen, globus pallidus and cerebral cortex.
Excess of movement - switches left on - movements easily activated.
Symptoms begin 30-50.

60
Q

Other symptoms of Huntington’s Disease

A

cannot learn new movements. Depression, memory impairment, anxiety, hallucination. May be misdiagnosed as schizophrenia.

61
Q

What happens when the cerebellum is damaged?

A

Trouble with aiming and timing. Difficulty programming the ange and distance of eye movements.

62
Q

What does cerebellum damage NOT impair?

A

Continuous motor activity (such as drawing continuous circles).

63
Q

The symptoms of cerebellar damage resemble those of…

A

alcohol consumption. - clumsiness, slurred speech, inaccurate eye movements.

64
Q

The cerebellum responds to violations of…

A

sensory expectations.

65
Q

What makes up the basal ganglia?

A

The caudate nucleus, putamen, globus pallidus.

66
Q

What are the caudate nucleus and putamen together known as?

A

The Striatum or dorsal striatum.

67
Q

What are the basal ganglia particularly important for?

A

spontaneous, self-initiated behaviours, not for stimulus-elicited actions.

68
Q

Is the basal ganglia responsible for selecting movements or for regulating the vigor of the movement?

A

Regulating the vigor!

69
Q

How do we know the basal ganglia isn’t responsible for selecting movements?

A

The cells in the primary motor cortex become active before those in the basal ganglia.

70
Q

Activity in the indirect pathway makes responses…

A

slower and less vigorous.

71
Q

The striatum receives input from the…

A

cerebral cortex ans ubstantia nigra.

72
Q

The striatum sends its output to the…

A

globus pallidus.

73
Q

The globus pallidus sends its output to the…

A

thalamus and frontal cotext.

74
Q

What are the two pathways and what are they for?

A

Direct and indirect. Direct pathway enhances the selected movement, indirect pathway inhibits inappropriate competing movements.

75
Q

Which pathway is essential for learned performance?

A

The indirect pathway.

76
Q

What does damage to the striatum do?

A

Animals still learn to choose response that produces larger reward, but response vigor is no large than reduced reward. Similar in parkinson’s; spontaneous movement are slow and weak, as if they feel little motivation to move.

77
Q

What happens when dopamine pathway to striatum becomes less active?

A

Depressed mood and lack of motivation.

78
Q

Which are the most important brain areas for learning new skills?

A

All of them.

79
Q

What’s being used when a glass we’re holding slowly fills up, which allows us not to drop the glass as it gets heavier?

A

Muscle spindles (mostly).

80
Q

What is a muscle spindle?

A

A proprioceptor.

81
Q

What do golgi tendon organs respond to?

A

Muscle tension.

82
Q

What do muscle spindles respond to?

A

Muscle stretching.

83
Q

What are golgi tendons desined to do?

A

Found in the tendons at opposite ends of a muscle, they act as a brake against an excessively vigorous contraction.

84
Q

Does the golgi tendon release acetylcholine directly onto the alpha motor neuron?

A

No. It releases onto an inhibitory interneuron in the spinal chord connected to the alpha motor neuron, causing the motor neuron to stop firing, relaxing the muscle.

85
Q

Where are central pattern generators?

A

In the spinal chord.

86
Q

Do central pattern generators need continual stimulation to continue?

A

No. Once stimulated, they will continue.

87
Q

What is a dog kicking it’s leg when you give it belly rubs an example of?

A

A central pattern generator.

88
Q

Are motor programs more complex or more simple movements?

A

These are more complex movements (a sequence, non-repetitive).

89
Q

Where are innate motor programs found? In the spine?

A

No, elsewhere. Perhaps the brainstem.

90
Q

Can motor programs be interrupted when they are consciously thought about?

A

yes!

91
Q

Some examples of innate motor programs?

A

Innate - Yawning, self-washing, checking eggs (animals).

92
Q

Where are learned motor programs stored?

A

The supplementary motor area.

93
Q

Some examples of learned motor programs?

A

Learning to drive, playing an instrument

94
Q

How few neurons could be between the brain and the muscle (for finer movements)?

A

As few as 2.

95
Q

What is the delay between thinking about movement and the movement itself?

A

300ms. Why the delay? Action potentials etc.