Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

HSE303 > Module 5 - Metabolic factors in muscle fatigue > Flashcards

Module 5 - Metabolic factors in muscle fatigue Flashcards

1
Q

Define fatigue

A

A reduction in muscle force or power that occurs during exercise, and which is reversible with adequate recovery.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Why do muscles fatigue?

A
  • Fatigue is essential process that ensures muscle cell survival.
  • Fatiguing mechanisms prevent harmful effects of extreme acidosis, complete muscle fibre ATP loss and calcium induced cellular damage.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

The precise cause of exercise-induced fatigue varies depending on…

A
  • Intensity, duration and mode of exercise
  • Environmental conditions
  • Nutritional and training status
  • Individual characteristics (e.g. muscle fibre type composition)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Peripheral (muscle) fatigue

A
  • When skeletal muscle is unable to generate required force or power despite unchanged or increasing neural drive from the CNS.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Processes involved in muscle activation:

Sliding filament theory

A

The mechanism by which muscles contract at a cellular level.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Processes involved in muscle activation: Sliding filament theory

Each muscle is composed of…

A

Bundles of muscle fibres

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Processes involved in muscle activation: Sliding filament theory

Each bundle of muscle fibres contains…

A

numerous individual fibres

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Processes involved in muscle activation: Sliding filament theory

Each muscle fibre contains

A

cylindrical organelles (myofibrils)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Processes involved in muscle activation: Sliding filament theory

What are myofibrils?

A

Bundles of proteins, called actin and myosin.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Processes involved in muscle activation: Sliding filament theory

Surrounding the myofibril is a network of…

A

tubules and channels, called the sarcoplasmic reticulum (SR).

SR is where calcium is stored.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Processes involved in muscle activation: Sliding filament theory

Each myofibril can be broken down into segments, called…

A

sarcomeres.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Processes involved in muscle activation: Sliding filament theory

Sarcomeres consist of

A

actin and myosin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Processes involved in muscle activation: Sliding filament theory

When nerve impulse arrives at muscle, it causes…

A

release of a chemical, called acetylcholine.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Processes involved in muscle activation: Sliding filament theory

Acetylcholine causes depolarisation, allowing

A

calcium to be released from SR.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Processes involved in muscle activation: Sliding filament theory

The released calcium binds to troponin, changing its

A

shape and moving tropomyosin from the active site of the actin.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Processes involved in muscle activation: Sliding filament theory

The myosin filaments can now…

A

attach to actin, forming a cross-bridge.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Processes involved in muscle activation: Sliding filament theory

The breakdown of ATP releases energy, enabling…

A

myosin to pull the actin filaments inwards, thus contracting the muscle.

This occurs along the entire length of every myofibril in the muscle cell.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Processes involved in muscle activation: Sliding filament theory

When ATP molecule binds to myosin head, the myosin…

A

detaches from actin, and the cross-bridge is broken.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Processes involved in muscle activation: Sliding filament theory

When ATP is then broken down, the myosin head can…

A

again attach to actin binding site, further along the actin filament, and repeat the process.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Processes involved in muscle activation: Sliding filament theory

This repeat pulling of the actin over the myosin, known as…

A

ratchet mechanism.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Processes involved in muscle activation: Sliding filament theory

This process of muscle contraction can last as long as there is…

A

adequate ATP and calcium stores.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Processes involved in muscle activation: Sliding filament theory

Once nerve impulse stops…

A

the calcium is pumped back to SR and actin returns to its resting position, causing the muscle to lengthen and relax.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Therefore, is fatigue prevents muscle from generating the required force, it must be either due to a:

A
  1. Reduction in number of cross-bridges formed per cross-sectional area of the muscle, and/or;
  2. Reduced force produced per cross-bridge formed
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Peripheral fatigue is characterised by a slowing of muscle shortening velocity and muscle relaxation time

A

Evident when comparing contractile properties of fatigued muscles with those of non-fatigued muscles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Shortening velocity

A
  • Reflects rate of cross-bridge cycling.
  • Therefore, fatigue must slow cross-bridge cycling.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

A slowing of muscle shortening velocity decreases muscle power, given that:

A

Power = force x distance shortened/time or;

Power = force x velocity of shortening

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Normal rates of muscle relaxation require…

A
  • Calcium release to stop
  • Calcium reuptake to occur
  • Detachment of calcium from troponin
  • Termination of cross-bridge cycling to occur

…One or more of these processes must be inhibited when muscle is fatigued.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Increase in muscle relaxation time

A
  • Interferes with co-ordination of muscle contractions (e.g. a muscle is still active when it shouldn’t be) during dynamic exercise, making movement less efficient and effective.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Potential sites of muscle fatigue

A
  1. Sarcolemma
  2. T-tubule
  3. Ca2+ release
  4. Ca2+ re-uptake
  5. Cross-bridge
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

During intense exercise (e.g. 3-5 max weight lifts, 400-800m running, all-out Wingate testing)

A

Near maximal muscle force or power is required.

Most, if not all, muscle fibres in the contracting muscle are active.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

During intense exercise, we see decreases in…

A
  • ATP
  • PCr
  • pH
  • Glycogen
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

During intense exercise, we see increases in…

A
  • Mg2+
  • Free ADP
  • Inorganic phosphate (Pi)
  • IMP
  • Cr
  • Lactate
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

During intense exercise, the contracting muscle is clearly unable to supply ATP at a sufficient rate to match the rate at which ATP is being used (this is why ATP levels fall):

A
  • The onset of fatigue is correlated with ability to supply ATP from anaerobic sources.
  • Correlation does NOT prove cause and effect.
  • In this example, muscle force may be decreasing because anaerobic metabolism is unable to supply enough energy to fuel contraction or conversely anerobic energy supply is decreasing because the muscle energy demand is decreasing.
  • It is possible that the drop in muscle force is due to something other than a reduction in anaerobic metabolism (i.e. other experiments are needed).
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

What is likely causing fatigue in high intensity exercise and what mechanism does it affect the muscle?

A
  • Fast twitch glycolytic fibres (i.e. type 2B) produce most force or power, thus critical to performance of power athletes. However, these fibres fatigue more rapidly.
  • During intense exercise, fatigue occurs predominantly in fast twitch fibres (Type 2B)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

How susceptible fast twitch fibres are to fatigue compared with slow twitch fibres.

In fast twitch…

A

Fatigue begins within first 10 tetanic contractions, quite marked by 88 tetani.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

How susceptible fast twitch fibres are to fatigue compared with slow twitch fibres.

In slow twitch…

A

Small amount of fatigue was only visible after 500 tetani, only marginally more fatigue was observed after 1000 tetani.

This clearly shows that slow twitch fibres are quite fatigue resistant

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

There are several metabolic factors known to be involved in causing fatigue in fast twitch fibres during intense exercise:

A
  • Large loss of muscle ATP and K+
  • Elevations in muscle free ADP, Mg2+, Pi and H+ levels
  • These disturbances affect specific processes within fast twitch muscle, resulting in decreased contractile performance.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

Decline in muscle ATP and production of force:

Decline on average by ___% in mixed-muscle.

A

30-50%

39
Q

Decline in muscle ATP and production of force:

It is argued that this drop in ATP is not sufficient to affect activity of critical ATPases in the muscle, such as myosin ATPase, Ca2+ ATPase, etc.

A

Therefore the fall in ATP is not involved in the decline in muscle force.

40
Q

Decline in muscle ATP and production of force:

Others argue that using the average ATP drop in mixed-muscle is unwise,

A

and that it is the actual localised ATP levels within individual fibres that is important.

41
Q

Decline in muscle ATP and production of force:

There is good evidence that localised ATP levels in single fibres can fall a lot lower than the average, especially in fast twitch muscle fibres (type 2B).

A

Such evidence suggests that in these fast twitch fibres, the fall in ATP may be sufficient to cause a reduction in force produced by these fibres.

42
Q

What is the effect of low ATP levels on muscle force production in fast twitch fibres?

Experiments conducted on mechanically skinned, rat fast twitch fibres investigated the effect of decreasing ATP concentrations from 25% (2mM) to 1.25% (0.1 mM) of resting values.

A
  • Muscle twitch force was decreased by ~30% when ATP values were 25% of resting values and decreased when ATP was lowered further.
  • The decrease in fast twitch muscle force was not as pronounced, and only occurred at a much lower ATP concentration when titanically stimulated.
  • Overall, low ATP concentration caused decrease in muscle force in this experimental model.
43
Q

What causes the drop in muscle force when ATP levels fall to critical levels?

The obvious answer would be, Insufficient ATP to fuel cross-bridge = fewer cross-bridges attach to actin and produce force. However this is NOT correct!

A

Experimental data below shows that cross-bridges can generate similar or higher forces than normal, even at extremely low ATP levels.

44
Q

So how do low ATP levels cause a reduction in fast twitch muscle force if cross-bridges function is normal?

A
  1. Failure to propagate action potential along sarcolemmal / t-tubule membrane due to excessive K+ loss from muscle
  2. Reduced Ca2+ release from sarcoplasmic reticulum
45
Q

So how do low ATP levels cause a reduction in fast twitch muscle force if cross-bridges function is normal?

  1. Failure to propagate action potential along sarcolemmal / t-tubule membrane due to excessive K+ loss from muscle
A
  • Low ATP levels cause increased K+ loss from contracting muscle = reducing K+ concentration gradient across the sarcolemma.
  • Given that resting membrane potential is predominantly determined by K+ concentration gradient, the fall in gradient causes depolarisation of muscle resting membrane potential.
  • This then inactivates voltage-gated Na+ channels needed to generate muscle action potential, so no further action potentials can occur in affect parts of the membrane.
  • Leads to failure of muscle membrane to propagate action potentials along the sarcolemma and into the t-tubules.
  • No action potential signal reaches the SR and no Ca+ is released to trigger the action of the fibre.
46
Q

So how do low ATP levels cause a reduction in fast twitch muscle force if cross-bridges function is normal?

  1. Reduced Ca2+ release from the sarcoplasmic reticulum
A
  • Low levels of cytoplasmic ATP may act to reduce muscle force is to prevent the opening of Ca2+ release channels (aka. Ryanodine receptors; RYR) in SR = decreasing release of Ca2+ from the SR.
  • Results in less Ca2+ available to bind to troponin = causing fewer myosin heads to bind to actin to form cross-bridges and produce force.
47
Q

How does a fall in muscle ATP levels cause increase in muscle K+ loss?

A
  • Drop in ATP compromises activity of Na+, K+ ATPase (i.e. the pump responsible for maintaining Na+ and K+ concentrations across the sarcolemma.
  • However, local drop in ATP levels need to be large to effect pump activity.
  • More likely, a drop in muscle cell ATP levels triggers opening of ATP dependent K+ channels, allowing greater efflux of this ion from contracting muscle.
48
Q

The falling muscle fibre ATP levels in conjunction with rising Mg2+ levels, results in marked decrease in SR Ca2+ release in rat fast twitch fibres

A
  • Free Mg2+ concentrations always rise in muscle cell in direct response to fall in ATP levels.
  • This is because ATP binds Mg2+ and when ATP is hydrolysed to form ADP, most of Mg2+ is released = increasing free Mg2+ levels in the cell.
49
Q

How does a fall in ATP and rise in Mg2+ cause a reduction in SR Ca2+ release?

Normally, action potential travels along the sarcolemma and into the t-tubular system…

A

…where it activates voltage-sensory molecules which open the ryanodine receptor, RyR (channels embedded in the SR membrane and allow calcium to come out of the RyR, into the SR, and down onto the filament, to allow cross-bridge cycling to take place).

50
Q

How does a fall in ATP and rise in Mg2+ cause a reduction in SR Ca2+ release?

When RyR is triggered to open, calcium…

A

leaves the SR and moves via that RyR channel, out into the cytoplasm, to bind to troponin.

51
Q

How does a fall in ATP and rise in Mg2+ cause a reduction in SR Ca2+ release?

For this channel to open, ATP must be …

A

bound to RyR

52
Q

How does a fall in ATP and rise in Mg2+ cause a reduction in SR Ca2+ release?

If magnesium is bound to RyR…

A

the channel will not open

53
Q

How does a fall in ATP and rise in Mg2+ cause a reduction in SR Ca2+ release?

For RyR to open, the voltage-sensor (which is a protein with enriched positive charge) moves…

A

towards RyR and the magnesium, which repels the magnesium and pushes it off the RyR.

54
Q

How does a fall in ATP and rise in Mg2+ cause a reduction in SR Ca2+ release?

When the magnesium is off the RyR channel, and ATP is bound to the RyR =

A

the channel will then open, allowing calcium to be released from SR.

55
Q

How does a fall in ATP and rise in Mg2+ cause a reduction in SR Ca2+ release?

Some of the diffused calcium can bind to a calcium-binding component, which…

A

keeps the channel open for longer, so more calcium can be released from SR.

56
Q

What causes the large fall in muscle ATP stores in fast twitch fibres?

A

1) Depletion of PCr stores

2) Inhibited action of glycolytic enzymes caused by acidosis

57
Q

What causes the large fall in muscle ATP stores in fast twitch fibres?

1) Depletion of PCr stores

Fast twitch muscle fibre PCr content…

A

falls to very low levels during intense exercise.

58
Q

What causes the large fall in muscle ATP stores in fast twitch fibres?

1) Depletion of PCr stores

Extremely rapid source of ATP production…

A

can no longer occur.

59
Q

What causes the large fall in muscle ATP stores in fast twitch fibres?

1) Depletion of PCr stores

Extreme depletion of PCr is associated with…

A

rapid decline in muscle ATP stores.

60
Q

What causes the large fall in muscle ATP stores in fast twitch fibres?

1) Depletion of PCr stores

Increasing PCr stores in muscle via dietary creatine supplementation can…

A

better maintain ATP stores in intensely contracting muscle and improve exercise performance.

61
Q

What causes the large fall in muscle ATP stores in fast twitch fibres?

1) Depletion of PCr stores

These findings show that PCr stores are important to…

A

maintain ATP levels in intensely contracting muscle and that elevating PCr stores can help delay muscle fatigue.

62
Q

Inhibition of glycolytic enzymes caused by acidosis:

ATP supply cannot keep up with ATP demand during intense contractions because…

A

there is an inhibition of glycolysis caused by an accumulation of H+.

63
Q

Inhibition of glycolytic enzymes caused by acidosis:

Acidosis inhibits activity of glycogen phosphorylase and…

A

slows muscle glycogen breakdown and glycolytic ATP production.

64
Q

Other metabolic factors causing a reduction in muscle force?

A

Inorganic Phosphate (Pi)

65
Q

How is Pi produced?

Intramuscular Pi can increase __-fold during intense exercise, with greatest rises in fast twitch fibres.

A

10

66
Q

How is Pi produced?

Increase in Pi is derived from…

A

ATP hydrolysis, which markedly increases with contractile activity, and is also greater in fast twitch fibres.

67
Q

How is Pi produced?

During intense contractions the rise in muscle Pi correlates with…

A

fall in ATP and CrP levels

68
Q

How does Pi cause a drop in muscle force?

Elevation in Pi is likely cause of __% decline in force observed in early fatigue.

A

10%

69
Q

How does Pi cause a drop in muscle force?

1) Increase in intramuscular Pi inhibit calcium release from the SR in two ways:

A

1) Pi can act directly on calcium release channels in the SR inhibiting their opening, thereby preventing calcium release from the SR; or

2) Cytosolic Pi can enter SR and bind to free calcium in SR to form calcium phosphate (Ca2+ phosphate). Ca2+ phosphate is not soluble and forms precipitate thereby trapping Ca2+ in the SR, as only free Ca2+ can traverse through an open calcium release channel.

70
Q

How does Pi cause a drop in muscle force?

2) A rise in Pi inhibits

A

attached cross bridges moving from a weak to strong binding state as an increase in Pi makes it more difficult for Pi to be released from the myosin head.

71
Q

How does Pi cause a drop in muscle force?

3) A rise in Pi decreases free energy released from ATP hydrolysis, causing…

A

insufficient energy to be available to drive Ca2+ ATPase and Na+, K+ ATPase activity.

72
Q

How does Pi cause a drop in muscle force?

4) Pi decreases ability of calcium to bind to troponin (decreases myofribilar Ca2+ sensitivity). Therefore…

A

more Ca2+ has to be released from SR to produce same muscle force.

NOTE: during late fatigue, Ca2+ release from SR is reduced not increased.

Consequently, decrease in myofibrillar Ca2+ sensitivity results in reduced number of cross-bridges attached to actin and therefore decreased muscle force.

73
Q

Summary of metabolic factors causing a decrease in muscle fatigue in fatiguing fast twitch fibres during exercise:

A large decrease in muscle ATP can contribute to…

A

excessive loss of K+ from contracting muscle which may result in failure to propagate muscle action potential.

74
Q

Summary of metabolic factors causing a decrease in muscle fatigue in fatiguing fast twitch fibres during exercise:

A large decrease in muscle ATP levels and concomitant increase in Mg2+ levels can…

A

reduce SR calcium release resulting in fewer cross-bridges attaching to actin.

75
Q

Summary of metabolic factors causing a decrease in muscle fatigue in fatiguing fast twitch fibres during exercise:

Increased muscle Pi causes:

A
  1. decreased SR calcium release
  2. decreased myofibrillar calcium sensitivity
  3. decrease number of cross-bridges in the strong (force) producing state; and
  4. decreased free energy release from ATP hydrolysis.

All these processes contribute to a decrease in muscle force.

NOTE: Increases in H+, lactate and ADP do not cause a reduction in muscle force!

76
Q

Metabolic factors that slow muscle shortening velocity in fatiguing fast twitch fibres during intense exercise:

Fast-twitch muscle shortening velocity is reduced by __% in fatigued fibres and will affect production of muscular power (Power = force x distance/time (velocity).

A

30

77
Q

Metabolic factors that slow muscle shortening velocity in fatiguing fast twitch fibres during intense exercise:

Major factor slowing muscle shortening velocity during intense exercise is…

A

accumulation of free ADP in the fibre.

78
Q

Metabolic factors that slow muscle shortening velocity in fatiguing fast twitch fibres during intense exercise:

Increase in free ADP levels inhibits release of…

A

ADP from myosin head, slowing the power stroke and the rate of cross-bridge cycling. This in turn reduces the muscle shortening velocity.

79
Q

Metabolic factors that slow the muscle relaxation rate during intense exercise:

A
  • Muscle fibre relaxation rate is slowed with fatigue during intense exercise.
  • Fibres still produce force when normally they should be switched off.
  • This likely limits dynamic exercise performance as it interferes with co-ordinated muscle activity, making movement less efficient and effective.
80
Q

Metabolic factors that slow the muscle relaxation rate during intense exercise:

Alternatively, a slowing of fibre relaxation rate could be beneficial during prolonged intense isometric contractions as a…

A

a lower rate of nerve impulses are required to keep the fibre maximally active.

81
Q

Metabolic factors that slow the muscle relaxation rate during intense exercise:

Muscle fibre relaxation involves:

A
  • Ceasing SR Ca2+ release
  • Reuptake of Ca2+ into the SR (Ca2+ ATPase activity)
  • Dissociation of Ca2+ from troponin; and
  • Cessation of cross-bridge cycling
82
Q

Metabolic factors that slow the muscle relaxation rate during intense exercise:

The metabolites known to slow muscle fibre relaxation rate are…

A

depletion of ATP; and

elevations of H+, ADP, Pi and reactive oxygen species (ROS)

83
Q

Fatigue in endurance exercise correlates with muscle glycogen depletion

A

It has been known that since the late 60s, endurance exercise capacity at intensity around 60-85% VO2max is severely compromised when muscle glycogen is depleted to very low levels.

84
Q

How does glycogen loading help?

A

If endurance exercise is started with higher glycogen levels (high CHO stores), time to fatigue will increase.

85
Q

How does glycogen depletion cause fatigue in endurance athletes?

A
  • Research shows that muscle glycogen depletion reduces SR Ca2+ release, thus force production.
  • However the reason for this is currently unknown.
86
Q

There are 3 stores of glycogen within skeletal muscle fibres:

A

1) Subsarcolemmal (i.e. just below the muscle membrane)

2) Intermyobrillar (i.e. between myofibres)

3) Intramyofibril (i.e. within the myofibre)

87
Q

Low intensity exercise (i.e. slower contractions) preferentially deplete…

A

Intramyofibrillar and intermyofibrillar glycogen stores, but not the subsarcolemmal stores

88
Q

There is a significant correlation between amount of intramyofibril glycogen present and the amount of SR Ca2+ released by the fibre

A
  • Shows link between depletion of glycogen pool and failure to release Ca2+from SR.
  • Researchers need to find mechanism causing this link.
  • One possibility could include lack of local fuel resulting in localised drop in ATP and reduction in binding of ATP to Ca2+ release channel (i.e. RyR), which would prevent opening of the channel and release of Ca2+ from the SR.
89
Q

Other factors that could be involved in causing fatigue during endurance exercise

A

Reactive Oxygen Species (ROS) (incl. superoxide anion, hydrogen peroxide, hydroxyl radical)

Reactive Nitrogen Species (RNS) (incl. nitric oxide, which can react with superoxide to form peroxynitrate)

90
Q

Impact of ROS/RNS…

A
  • Both are molecules with unpaired electrons, which makes them highly reactive.
  • They can damage lipids, proteins and DNA.
  • Interfere with cellular function
91
Q

ROS/RNS production in muscle increases with

A
  • Exercise
  • Temp
  • Elevated intracellular (Ca2+)
92
Q

Decreasing ROS/RNS using antioxidants has been shown…

A
  • To delay fatigue during endurance exercise but not during high-intensity exercise.
  • Suggests that ROS/RNS may be involved in causing fatigue in endurance exercise.
93
Q

The precise mechanism of how they contribute to fatigue is unknown. Evidence seems to indicate that these molecules…

A
  • Reduce myofibrillar Ca2+ sensitivity.
  • The free radicals interfere with binding of Ca2+ to troponin molecules.
  • Therefore, more Ca2+ needs to be released from SR to get similar muscle force response.

HSE303 (6 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions