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PE > Neuromuscular system > Flashcards

Neuromuscular system Flashcards

1
Q

What is the sympathetic nervous system?

A

It prepares the body for exercise and is often referred to as the ‘fight or flight response’.

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2
Q

What is the parasympathetic nervous system?

A

It has the opposite effect of the sympathetic system - it relaxes the body and slows down many high energy functions. ‘Rest and relax’.

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3
Q

What are the three main types of muscle fibre?

A

Slow oxidative (type 1)
Fast oxidative glycolytic (type 2a)
Fast glycolytic (type 2x)

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4
Q

What are the functional characteristics of Slow oxidative muscle fibres?

A

Slow [110] contraction speed
Slow motor neurone conduction capacity
Low force produced
Low fatigability
Very high aerobic capacity
Low anaerobic capacity
Low myosin ATPase / glycolytic enzyme activity
Red in colour

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5
Q

What are the structural characteristics of Slow oxidative muscle fibres?

A

Small motor neurone size
High mitochondrial density
High capillary density
High myoglobin content

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6
Q

Which sport / activity are slow oxidative muscle fibres suited to?

A

They are better adapted to low intensity exercise.
E.g. long distance running
They have specific characteristics that allow them to use oxygen more efficiently for aerobic respiration.

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7
Q

What are the functional characteristics of Fast oxidative glycolytic muscle fibres?

A

Fast [50 m/s] contraction speed
Fast motor neurone conduction capacity
High force produced
Medium fatigability
Medium aerobic capacity
High anaerobic capacity
High myosin ATPase / glycolytic enzyme activity
Pink in colour

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8
Q

What are the structural characteristics of Fast oxidative glycolytic muscle fibres?

A

Large motor neurone size
Medium mitochondrial density
Medium capillary density
Medium myoglobin content

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9
Q

Which sport / activity are fast oxidative glycolytic muscle fibres suited to?

A

The muscle fibres are more resistant to fatigue than type 2x so are used for events such as the 1500m or swimming where long bursts of energy are needed.

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10
Q

What are the functional characteristics of Fast glycolytic muscle fibres?

A

Fast [50] contraction speed
Fast motor neurone conduction capacity
High force produced
High fatigability
Low aerobic capacity
Very high anaerobic capacity
Very high myosin ATPase / glycolytic enzyme activity
White in colour

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11
Q

What are the structural characteristics of Fast glycolytic muscle fibres?

A

Large motor neurone size
Low mitochondrial density
Low capillary density
Low myoglobin content

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12
Q

Which sport / activity are fast glycolytic muscle fibres suited to?

A

These muscle fibres fatigue much quicker than type 2a and are used for highly explosive events such as 100m where a quick, short burst of energy is needed.

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13
Q

What is myoglobin?

A

Myoglobin is an iron-containing muscle pigment that stores oxygen in the muscle fibres to then be used quickly when exercise begins.

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14
Q

How many of each muscle fibre are there in the skeletal-muscular system?

A

There is a mixture of all three types of fibre but not in equal proportions.
The mix is genetically determined, though it is possible to train them to change.

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15
Q

What is the all or none law?

A

When a motor neurone stimulates its muscle fibres, either all of them contract or none at all.

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16
Q

What is a motor unit?

A

A motor neurone and its muscle fibres.
Only one type of muscle fibre is found in one particular motor unit.

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17
Q

How can the strength of contraction be controlled?

A

Type of muscle fibre
Motor unit size
Number of motor units
Increasing the rate of stimulation
Spatial summation
Wave summation

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18
Q

How does the type of muscle fibre affect strength of contraction?

A

Type 2 fibres produce more force than type 1.

19
Q

How does the number of motor units affect strength of contraction?

A

A higher number of motor units means a higher strength of contraction.
Experiences the all or none law

20
Q

What is tetanus?

A

The highest force of contraction, it is a smooth, sustained contraction rather than lots of small twitches (wave summation).

21
Q

What is a tetanic contraction caused by?

A

A series of fast repeating stimuli that do not allow the muscle to relax between contractions.

22
Q

What is the effect of training on muscle fibre type?

A

The size of muscle fibres can be increased through training - hypertrophy - which results in a greater strength in the muscle.

23
Q

What are motor neurones?

A

Nerve cells which transmit the brain’s instructions as electrical impulses to the muscles.

24
Q

What is a neuromuscular junction?

A

Where the motor neurone and muscle fibre meet.

25
Q

How do motor units vary in size?

A

A small muscle that is used for fine motor control will have motor units that only have a few muscle fibres per motor neurone.
A large muscle used for gross motor control will have motor units with hundreds of muscle fibres per motor neurone.

26
Q

What is the threshold?

A

The minimum amount of stimulation required to start a contraction.
If the sequence of impulses is equal to or more than the threshold, all the muscle fibres in the motor unit contract.
If the sequence of impulses is less, then no muscle action occurs.

27
Q

How does motor unit size affect the strength of contraction?

A

Motor units with more muscle fibres per motor neurone means a higher strength of contraction.

28
Q

What is wave summation?

A

Where there is a repeated nerve impulse with no time to relax so a smooth, sustained contraction occurs, rather than twitches.

29
Q

How does wave summation work?

A

Each time the nerve impulse reaches the muscle cell, calcium is released. Calcium needs to be present for a muscle to contract.
When there are repeated nerve impulses with no time to relax calcium will build up in the muscle cell.
This produces a forceful contraction (tetanus).

30
Q

What is spatial summation?

A

When the strength of contraction changes by altering the number and size of the muscle’s motor units.

31
Q

How does spatial summation occur?

A

When the impulses are received at the same time at different places on the neurone which add up to fire the neurone.
It is the recruitment of additional and bigger motor units within a muscle to develop more force.

32
Q

What is PNF?

A

Proprioceptive Neuromuscular Facilitation is an advanced stretching technique. It is the most effective form of flexibility training to increase range of motion.

33
Q

What is the CRAC technique?

A

Contract - Relax - Antagonist - Contract.
The most practical PNF technique.

34
Q

What are proprioceptors?

A

Sensory organs in the muscles, tendons and joints that inform the body of the extent of movement.

35
Q

What are muscle spindles?

A

Proprioceptors that lie between skeletal muscle fibres.
They detect how far and how fast a muscle is being stretched and produce the stretch reflex. (Often called stretch receptors).

36
Q

How do muscle spindles work?

A

Send the information (excitory signals) about the muscle to the Central Nervous System (CNS).
The CNS then sends an impulse back to the muscle telling it to contract, which triggers the stretch reflex.

37
Q

What are golgi tendon organs?

A

They are found between the muscle fibre and tendon. They are activated when there is tension in the muscle.

38
Q

How do golgi tendon organs work?

A

They detect levels of tension in the muscle.
When the muscle is contracted isometrically in PNF, they sense the increase in muscle tension and send inhibitory signals to the brain.
The signals override the excitory signals from the muscle spindles which delays the stretch reflex.

39
Q

What is autogenic inhibition?

A

When there is a sudden relaxation (and lengthening) of the muscle in response to high tension.
This occurs when the inhibitory signals are sent to the brain by the Golgi tendon organs.

40
Q

What is the first step in PNF?

A

The individual performs a passive stretch with the help of a partner and extends the leg until tension is felt.
This stretch is detected by the muscle spindles.
If the muscle is being stretched too far, a stretch reflex should occur.

41
Q

What is the stretch reflex?

A

It is triggered by the muscle spindles and it causes the muscle to contract to prevent over-stretching and reduce the risk of injury.

42
Q

What is the second step in PNF?

A

The individual then isometrically contracts the muscle for 10 seconds by pushing their leg against their partner who provides just enough resistance to hold the leg stationary.
The stretch reflex is delayed by the Golgi tendon organs.

43
Q

What is the third step in PNF?

A

As the leg is lifted again, the Golgi tendon organs are responsible for the antagonist muscle relaxing which means the leg stretches further.
This process can be repeated until no more gains are possible.

PE (30 decks)

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