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PE > Physiology of skeletal muscles > Flashcards

Physiology of skeletal muscles Flashcards

1
Q

Name 4 functional characteristics of slow twitch muscle fibres

A
  • slow speed of contraction
  • low force of contraction
  • high resistance to fatigue
  • Very high aerobic capacity
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2
Q

Name 5 structural characteristics of type IIx muscle fibres

A
  • Low mitochondrial density
  • Low capillary density
  • Low myoglobin content
  • Very high glycogen store
  • Large motor neuron size
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3
Q

What are 5 structural characteristics of Fast Oxidative glycolytic muscle fibres ?

A
  • Medium mitochondrial density
  • Medium Capillary density
  • Medium myoglobin content
  • High glycogen store
  • Medium motor neuron size
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4
Q

What are 4 functional characteristics of fast twitch glycolytic muscle fibres?

A
  • High speed of contraction
  • High force of contraction
  • Low resistance to fatigue
  • High anaerobic capacity
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5
Q

What are 5 structural characteristics of slow twitch oxidative muscle fibres?

A
  • High mitochondrial density
  • high capillary density
  • High myoglobin content
  • Low glycogen store
  • Small motor neurone size
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6
Q

Name 4 functional characteristics of fast twitch glycolytic muscle fibres

A
  • Very high speed of contraction
  • High force of contraction
  • Low resistance to fatigue
  • Very high anaerobic capacity
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7
Q

What are the roles of the sympathetic and parasympathetic nervous systems?

A
  • The sympathetic nervous system prepares the body for exercise (increases HR)
  • The parasympathetic nervous system helps the body to return to normal after exercise by relaxing high energy functions. (slows HR)
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8
Q

True or False?

We have a set number of muscle fibres in our body

A
  • False

- We have a mix of all 3 but not in equal proportions, it is genetically determined

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9
Q

What types of athlete would have slow twitch muscle fibres?

A
  • Long endurance athletes
  • Marathon runners
  • Long distance cycling-tour de France
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10
Q

Type IIa Muscle fibres are more common in what athletes?

A
  • Games athletes
  • Football
  • Basketball
  • Rugby
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11
Q

100 + 200m Sprinters, maximal + near maximal lifts would have mainly what muscle fibre types?

A
  • Type IIx/fast twitch glycolytic
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12
Q

What is a motor unit?

A
  • A motor neurone and the muscle fibres it is attached to
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13
Q

True or false?

Only one type of muscle fibre can be found in one particular motor unit

A
  • True!
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14
Q

How does a motor neurone stimulate the muscle fibre?

A
  • action potential travels through the motor neuron
  • a nerve impulse is sent
  • this stimulates the muscle fibre
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15
Q

What is the all or none law?

A
  • One motor neurone stimulates the muscle fibres, either all of them or none of them contract
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16
Q

Name 2 other parts of the all or none law

A
  • A minimum threshold is needed for the muscle fibres to contract
  • If the sequence of impulses is = to or more than the threshold then all muscle fibres in the motor unit will contract.
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17
Q

How can we vary the strength of contractions?

A
  • Recruit different sizes of motor units
  • Recruit more/less motor units
  • Recruit different muscle fibres (Type I/IIa/IIx)
18
Q

What is the effect of having a large/small motor unit?

A
  • Big MU=large force of contraction

- Small MU=small force of contraction

19
Q

What is the effect of recruiting more/less motor units?

A
  • More MU=larger force of contraction

- Less MU=Smaller force of contraction

20
Q

What muscle fibres cause a small force of contraction?

A

Slow twitch oxidative muscle fibres

21
Q

Fast twitch glycolytic muscle fibres cause what force of contraction?

A

A large force of contraction

22
Q

What does wave summation mean?

A
  • repeated nerve impulse
  • No time to relax
  • smooth sustained contraction occurs instead of muscle twitches
23
Q

What is the definition of spatial summation?

A
  • This is where the strength of the contraction will change depending on number and size of the motor unit
  • Delays fatigue as some motor units contract whilst some relax
  • determines whether or not there will be an action potential.
24
Q

What are tetanic contractions?

A
  • Bursts of increasing frequency to the nerve
  • Allowing a two minute period between stimuli for muscle recovery
  • Causes a sustained muscle contraction
25
Q

How does spatial summation delay fatigue?

A
  • Some motor units contract whilst some relax
26
Q

How would wave summation help a gymnast to produce a more powerful contraction?

A
  • Muscle is stimulated before it relaxes

- enables gymnast to apply greater force to adjust the height to match what is needed for her technique

27
Q

At what rate do type IIa muscle fibres produce ATP

A
  • Produce ATP at a fast rate due to the use of both aerobic and anaerobic systems
28
Q

What is the process of PNF stretching?

A
  • A muscle group is passively stretched
  • They then contract isometrically against resistance while in the stretched position
  • It is passively stretched again through the resulting increased range of motion.
29
Q

What type of contraction occurs during PNF?

A
  • Isometric contraction
30
Q

What is the contract-relax method?

A
  • The muscle group is passively stretched
  • It is then isometrically contracted for around 10 seconds
  • Muscle relaxed for appr. 2 secs
  • Stretched again for 10 secs
31
Q

What does CRAC stand for?

A
  • Contract Relax Agonist Contraction
32
Q

What is the process of CRAC?

A
  • Muscle group is passively stretched
  • Isometrically contracted against resistance for around 10 seconds
  • Active stretch is applied
33
Q

What is the difference between a passive and active stretch?

A
  • An active stretch doesn’t require a partner, you are stretching the muscle yourself
  • A passive stretch is where an external force is being applied
34
Q

What is the Golgi tendon organ?

A
  • Monitor information about the tension or force experienced by a muscle and tendon.
35
Q

During the contraction phase, significant amount of tension occurs within the muscle and tendons. What happens to the GTO?

A
  • The GTO is stimulated
  • Counteracting the stretch reflex caused by muscle spindle activation
  • This causes an inhibitory reflex
  • Relaxation of the muscles being worked on.
36
Q

How does the GTO enable a larger range of motion.

A
  • Relaxation of the stretched muscle and contraction of its antagonistically paired muscle
  • enables the joint to be taken to a greater range of motion
  • This leads to improved adaptations in muscle length.
37
Q

What happens when a high force could lead to injury in either the muscle of tendon?

A
  • When high force could lead to injury in the muscle or tendon, the GTO causes an inhibitory reflex.
38
Q

What is an inhibitory reflex?

A
  • a relaxation of the whole muscle
39
Q

Explain the difference between tetanic summation and wave summation (4 marks)

A
  • Tetanic summation allows maximal force to be produced by motor units
  • This is because maximal impulses are sent down a nerve.
  • In wave summation many impulses are sent down a nerve
  • they gradually add together to produce a larger force but it is sub-maximal
40
Q

Discuss the use of Type 2a Muscle fibre type in a basketball match. (5 Marks)

A
  • Fast speed of contraction,
  • Lots of fast movements in match,
  • High force of contraction allowing higher jumps and more power
  • Medium aerobic capacity.
  • Allows muscles to work for the duration of the game is not too long.
41
Q

Describe a method for creating a larger force of contraction. (2 Marks)

A
  • Tetanic summation
  • greatest amount of impulses sent to muscles
  • causing them to contract with the largest force possible
  • more motor units innovated
42
Q

Describe the process of post-isometric relaxation

A
  • controlled by Golgi tendon organ
  • When muscles are contracted isometrically for a long period muscle inhibition will occur
  • This results in the muscle relaxing

PE (14 decks)

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