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Physiology of skeletal muscles Flashcards

(42 cards)

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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?

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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?

Study These Flashcards
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?

Study These Flashcards
A
  • More MU=larger force of contraction

- Less MU=Smaller force of contraction

20
Q

What muscle fibres cause a small force of contraction?

Study These Flashcards
A

Slow twitch oxidative muscle fibres

21
Q

Fast twitch glycolytic muscle fibres cause what force of contraction?

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A

A large force of contraction

22
Q

What does wave summation mean?

Study These Flashcards
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?

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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?

Study These Flashcards
A
  • Bursts of increasing frequency to the nerve
  • Allowing a two minute period between stimuli for muscle recovery
  • Causes a sustained muscle contraction
25
How does spatial summation delay fatigue?
- Some motor units contract whilst some relax
26
How would wave summation help a gymnast to produce a more powerful contraction?
- 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
At what rate do type IIa muscle fibres produce ATP
- Produce ATP at a fast rate due to the use of both aerobic and anaerobic systems
28
What is the process of PNF stretching?
- 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
What type of contraction occurs during PNF?
- Isometric contraction
30
What is the contract-relax method?
- 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
What does CRAC stand for?
- Contract Relax Agonist Contraction
32
What is the process of CRAC?
- Muscle group is passively stretched - Isometrically contracted against resistance for around 10 seconds - Active stretch is applied
33
What is the difference between a passive and active stretch?
- 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
What is the Golgi tendon organ?
- Monitor information about the tension or force experienced by a muscle and tendon.
35
During the contraction phase, significant amount of tension occurs within the muscle and tendons. What happens to the GTO?
- 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
How does the GTO enable a larger range of motion.
- 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
What happens when a high force could lead to injury in either the muscle of tendon?
- When high force could lead to injury in the muscle or tendon, the GTO causes an inhibitory reflex.
38
What is an inhibitory reflex?
- a relaxation of the whole muscle
39
Explain the difference between tetanic summation and wave summation (4 marks)
- 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
Discuss the use of Type 2a Muscle fibre type in a basketball match. (5 Marks)
- 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
Describe a method for creating a larger force of contraction. (2 Marks)
- Tetanic summation - greatest amount of impulses sent to muscles - causing them to contract with the largest force possible - more motor units innovated
42
Describe the process of post-isometric relaxation
- 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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