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Exercise Physiology > Musculoskeltal System > Flashcards

Musculoskeltal System Flashcards

1
Q

The Human Body Contains How many Skeletal Miscles

A

Greater Than 600

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2
Q

What are the 4 Functions of Skeletal Muscle

A
  1. Force production for locomotion and breathing
  2. Force Production for Posture Support
  3. Heat Production during cold stress
  4. Endocrine organ that plays a role in regulating other organ systems
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3
Q

Flecked

A

Decrease joint angle

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4
Q

Extensions

A

Increase joint angle

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5
Q

The connective Tissue Covering Skeletal Muscle

A
  1. epimysium
  2. Perimysium
  3. Endomysium
  4. Basement Membrane
  5. Sarcolemma
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6
Q

Epimysium

A

Surrounds entire muscle

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7
Q

Perimysium

A

Surrounds bundles of muscle fibers

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8
Q

Fascicles

A

Bundles of muscle fibers

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9
Q

Endomysium

A

Surrounds individual muscle fibers

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10
Q

Basement Membrane

A

Just below endomysium providing another protective layer

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11
Q

Sarcolemma

A

Muscle cell membrane that surrounds the muscle fiber

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12
Q

Satellite cells play a role

A

in muscle growth and repair

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13
Q

Strength Training causes growth enhancement by

A

Dividing and increasing the number of nuclei to the existing muscle fiber

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14
Q

More Nuclei Allow for

A

Greater protein synthesis for muscle growth

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15
Q

Myonuclear domain

A

The volume of cytoplasm surrounding each nucleus

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16
Q

Each nucleus can support

A

A limited myopic lead domain

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17
Q

A single nucleus can sustain the necessary gene expression for the production of proteins only for

A

A limited area of cell volume therefore to maintain a constant myonuclear domain new nuclei are added to muscle fibers during growth

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18
Q

Beneath the sarcolemma lies the

A

Sarcoplasm which contains cellular proteins organelles and myofibrils

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19
Q

Myofibrils

A

Contain contractile proteins - actin and myosin

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20
Q

Actin

A

Thin filament - contain the proteins troponin and tropomyosin which play a key role in the contractile process

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21
Q

Myosin

A

Thick filament

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22
Q

Sarcomere (subdivision of a myofibril)

A

Includes:

  1. Z line
  2. M line
  3. H zone
  4. A band
  5. I band
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23
Q

Z line

A

Divided each sarcomere

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24
Q

M line

A

The fine line in the middle of the H zone

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25
Q

H zone

A

Myosin filament with no overlap of actin located in the center of a sarcomere

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26
Q

A band

A

Dark portion of a sarcomere where myosin filaments are located

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27
Q

I band

A

Light region of the sarcomere where actin is primarily located

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28
Q

Sarcoplasmic Reticulum

A
  1. Membranous channels that surround each myofibril
  2. Storage site for calcium
  3. Terminal Cisternae (lateral sacs) enlarged portion of SR
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29
Q

Transverse Tubules

A

Extend from sarcolemma to SR and runs completely through the muscle fiber. Lies between the terminal Cisternae.

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30
Q

Neuromuscular Junction

A

Is the junction between the motor neuron and muscle fiber

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31
Q

Motor Unit

A

Motor neuron and all fibers it innervates

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32
Q

Motor Neurons extends

A

Outward from spinal cord

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33
Q

Motor end plate

A

Pocket formed around motor neuron by sarcolemma

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34
Q

Neuromuscular Cleft

A

Short gap between neuron and muscle fiber

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35
Q

Synaptic Cleft

A

Neuromuscular Cleft

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36
Q

Acetylcholine is released from

A

The motor neuron

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37
Q

Acetylcholine causes

A

An increase in the permeability of the sarcolemma to sodium which results in an end plate potential - depolarization of muscle

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38
Q

End Plate Potential

A

Muscle depolarization

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39
Q

The sliding Filament Model

A

Muscle shortening occurs due to the movement of the actin filament over the myosin filament causing muscle shortening and tension development which causes the formation of cross bridges between actin and myosin and the reduction in the distance between Z lines of the sarcomere

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40
Q

Power Stroke

A

Formation of cross bridges between actin and myosin filaments

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41
Q

Swinging lever arm model

A

Sliding filament model

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42
Q

Calcium binding to troponin causes

A

Tropomyosin to be removed from the active binding site on actin leading to cross bridge attachment

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43
Q

ATP is required for

A

Muscle contraction

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44
Q

Myosin ATPase

A

Breaks down ATP as fibers contract

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45
Q

Myosin ATPase is located

A

On the head of the myosin cross bridge

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46
Q

ATP breakdown leads to

A

Muscle shortening by energizing myosin cross bridges

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47
Q

EC coupling

A

Depolarization of motor end plate in coupled to muscular contraction by

  • action potential travels down the transverse tubules and causes release of calcium from the SR
  • Calcium binds to troponin causing a position change in tropomyosin and exposing the active sites on actin
  • Strong binding state formed btw actin and myosin
  • contraction occurs
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48
Q

Excitation

A
  1. Nerve signal arrives at synaptic knob
  2. Ach is released into synaptic cleft and bonds to receptors on motor end plate, which open ion channels allowing sodium to enter the muscle fiber
  3. Sodium influx causes depolarization that is conducted down transverse tubules
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49
Q

Contraction

A
  1. Depolarization of T-Tubules causes release of calcium from the SR
  2. Calcium binds to troponin causing a shift in tropomyosin to uncover myosin binding sites on actin
  3. Myosin binds to actin to form cross bridges
  4. Pi is released from myosin and cross bridge movement occurs
  5. New ATP attaches to myosin breaking the cross bridge. Then ATP is broken down which energizes myosin
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50
Q

Relaxation

A
  1. Motor Neuron Stimulation ends, Ach is no longer released and muscle fibers repolarizes
  2. Calcium is pumped back into SR and tropomyosin returns to original position covering myosin binding sites on actin and muscle relaxation occurs
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51
Q

Cross Bridges Require

A

ATP

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52
Q

After the inorganic phosphate leaves the cross bridge the myosin head moves producing the

A

Power stroke

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53
Q

Muscle Fatigue

A

A decline in muscle power output by a decrease in force generation and a decrease in shortening velocity

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54
Q

Muscle fatigue is caused by

A

Disturbances in the CNS and peripheral factors within skeletal muscles

55
Q

CNS fatigue from long duration exercise

A

A decrease in excitatory neurotransmitters in the motor cortex reduces motor neuron activation to skeletal muscle.

56
Q

Current Research Suggests that fatigue is due to both

A

Central and peripheral factors

57
Q

Peripheral Factors related to muscle fatigue

A

Peripheral factors disrupt cross bridge formation at high intensity ( ~60 seconds) and long duration (2-4 hours)

58
Q

High intensity exercise leads to muscle fatigue when

A

There is an accumulation of lactate, hydrogen ions, ADP, inorganic phosphate, and free radicals which diminishes cross bridges bound to actin which decreases force production.

59
Q

Long Duration Exercise leads to muscle fatigue when

A

There is an accumulation of free radicals, an electrolyte imbalance or glycogen depletion

60
Q

Source of ATP

A

Oxidative Phosphorylation

PC-ATP system

Glycolysis

61
Q

Fatigue is characterized by

A

A reduction in muscle force production and a decreased contraction time

62
Q

Muscle Cramps Are

A

Spasmodic involuntary muscle contractions

63
Q

Two theories of muscle cramps

A

Electrolyte and dehydration theory

And the altered neuromuscular control theory

64
Q

Electrolyte depletion and dehydration theory

A

Water and sodium loss via sweating causes spontaneous muscle contraction which causes motor nerve terminals to spontaneously discharge

65
Q

Altered neuromuscular control theory

A

Muscle fatigue causes abnormal activity in muscle spindle (increased activity) and golgi tendon organ (decreased activity) which leads to increased involuntary firing of motor neurons located in the spinal cord which causes muscle contractions or cramps

66
Q

Muscle cramps can be relieved by

A

Passive stretching

67
Q

Passive stretching relieves cramps by

A

Stretching activates Golgi tendon organs which inhibit motor neurons in the spinal cord resulting in muscle relaxation

68
Q

Inverse stretch reflex

A

Stretching activates Golgi tendon organs which inhibit motor neurons in the spinal cord resulting in muscle relaxation

69
Q

Inverse stretch reflex provides support

A

That impaired neuromuscular control is present in exercise induced muscle cramping

70
Q

Percentage o fiber types in skeletal muscle is related to

A

Genetics, blood levels of hormones and the exercise habits of the individual

71
Q

Biochemical properties of skeletal muscle

A

Oxidative Capacity

Type of Myosin ATPase

Abundance of contractile proteins within the fiber

72
Q

Oxidative Capacity

A

Number of capillaries, mitochondria and amount of myoglobin

Fatigue resistance

73
Q

Type of Myosin ATPase

A

Speed of ATP degradation

Results in high speed of muscle shortening

74
Q

High ATPase activity

A

High ATP breakdown capability

75
Q

Abundance of contractile proteins within the fiber

A

Large amounts of actin and myosin relate to being able to produce more force

76
Q

Contractile Properties of skeletal Muscle

A
  1. Maximal Force Production
  2. Speed of Contraction
  3. Maximal Power Output
  4. Muscle Fiber Efficiency
77
Q

Maximal Force Production

A

Force per unit of cross sectional area

78
Q

Speed of contraction

A

Myosin ATPase activity

79
Q

Vmax is determined by

A

The rate of cross bridge cycling

80
Q

Maximal Power Output

A

Determined by force generation and shortening velocity

81
Q

Muscle Fiber Efficiency

A

Measure of muscle fiber economy

  • the less ATP used to produce a greater force the more efficient it is
82
Q

Muscle Fiber Efficiency Formula

A

ATP uses/Forced Produced

83
Q

Muscle Biopsy

A

Small piece of muscle is removed

84
Q

Staining for types of myosin ATPase

A

Type I fibers are the lightest and appear blue

Type IIa appear intermediate and are green

Type IIx appear the darkest and are black

Dystrophin appears red

85
Q

Immunogistological staining

A

Selective antibody binds to a unique myosin proteins fiber types are differentiated by color difference

86
Q

Gel electrophoresis allows you to identify

A

Myosin isoforms specific to different fibers types

87
Q

Dystrophin

A

Protein in sarcolemma

88
Q

Type 1 fibers

A

Slow twitch/Slow Oxidative

High # of mitochondria
High Resistance to Fatigue
Aerobic Respiration dominates
Low ATPase activity 
Low Vmax 
Highly efficient 
Moderate specific Tension
89
Q

Type IIa

A

Intermediate Fibers/Fast Oxidative -Glycolytic Fibers

High/moderate # of mitochondria
High/moderate Resistance to Fatigue
Aerobic and Anaerobic Respiration
High ATPase activity 
High Vmax 
Moderately Efficient
High specific tension
90
Q

Type IIx

A

Fast twitch/Fast Glycolytic

Low # of mitochondria
Low Resistance to Fatigue
Anaerobic  Respiration dominates
High ATPase activity 
High Vmax 
Not efficient 
High specific Tension
91
Q

Type 1 fibers have less

A

Contractile proteins than type 2 for a specific area

92
Q

Fast fibers exert more force

A

Than type 1 fibers because they contain more myosin cross bridges per cross sectional area

93
Q

Type 1 fibers have low Vmax capabilities

A

Due to low myosin ATPase activity

94
Q

Non-athletes have

A

Half slow and half fast fibers

95
Q

Power athletes

A

Have a high percentage of fast fibers

96
Q

Endurance athletes have

A

A higher percentage of slow fibers

97
Q

Muscle Action Describes

A

The process of force development

98
Q

Isometric action

A

Static exercise

The muscle exerts force with out changing length

99
Q

Examples of isometric action

A

Pulling against an immovable object

Postural muscles during sitting or standing

100
Q

Dynamic action

A

Isotonic exercise

Can be concentric or eccentric

101
Q

Concentric action

A

Muscle shortens during force production

102
Q

Eccentric Action

A

Muscle produces force but length increases

103
Q

Eccentric action is associated with

A

Muscle fiber injury and delayed onset muscle soreness

104
Q

Muscle Twitch

A

Contraction as the result of a single stimulus like electrical shock

Consisting of a
Latent Period immediately after stimulus and lasting approximately 5 ms

Contraction Period where tension is developed lasting approximately 40 ms

Relaxation period where the muscle returns to the original length lasting approximately 50 ms

105
Q

Speed of shortening is greater in

A

Fast fibers because

SR releases Calcium at a faster rate and higher ATPase activity

106
Q

Force exerted during muscle contraction is dependent on 3 factors

A

Type and number of motor units recruited

Initial muscle length

Nature of the neural stimulation of motor units

107
Q

Types and number of motor units recruited

A

More motor units = greater force

More Fast Motor Units = greater force

108
Q

Initial muscle length

A

Increased cross bridge formation at ideal length

109
Q

Neural stimulation

A

Simple twitch

Summation

Tetanus

110
Q

Summation

A

Addition of successive twitches causes increased force

111
Q

Tetanus

A

Increasing stimuli so rapidly so that the individual contractions blend into a single sustained contraction

112
Q

As the frequency of neural stimulation increases

A

The force developed increases

113
Q

Force velocity relationship

A

At any absolute force the speed of movement is greater in muscles with higher percentages of fast twitch fibers

114
Q

The maximum velocity of shortening is greatest

A

at the lowest force

115
Q

The peak power increases with velocity up to movement spee doc

A

200-300 degrees/second

Power decreases beyond this velocity because force decreases with increasing movement speed - that is because rapid shortening restricts the number of cross bridges between actin and myosin limiting force production

116
Q

Mykonos

A

Small signaling molecules released by skeletal muscle. They act as hormones or hormone messengers that affect a variety of other tissues

117
Q

Skeletal muscle produces my planes when it

A

Contracts stimulating glucose uptake and fatty acid oxidation

Promoting blood vessel growth in muscle

Promoting liver glucose production and TGA breakdown

118
Q

IL-6

A

Principle myofibril produced during exercise

Pro and anti inflammatory

Inhibits TNF a and other antionflammatories

119
Q

Regular exercise

A

Promotes antionflammatory environment

120
Q

Proprioceptors

A

Provide CNS with information about body position

They are located in joints and muscles

121
Q

Kinesthesia

A

Related to conscious recognition of the body parts with respect to one another and to limbs movement rates

122
Q

Joint Propioceptors

A
  1. Free nerve endings sensitive to touch and pressure - initially strongly stimulated at the beginning of movement and then become less sensitive
  2. Golgi type receptors - found in ligaments and around joints
  3. Pacinian Receptors

In tissues and around joints

Detect the rate of joint rotation

123
Q

Muscle Proprioceptors

A

Provide sensory feedback to the nervous system concerning relative muscle length and tension development by muscle

  1. Muscle spindle
  2. Golgi tendon organ
124
Q

Muscle Spindle

A

Respond to changes in muscle length that require the finest degree of control

125
Q

Muscle spindles consist of

A

Intrafusal Fibers
Gamma Motor Neurons
Sensory Nerve Endings

126
Q

Intrafusal Fibers

A

Run parallel to normal muscle fibers and insert into connective tissue with in muscles

127
Q

Intrafusal fibers are composed of

A

Several thin muscle cells

128
Q

Extrafusal Fibers

A

Normal muscle fibers

129
Q

Gamma Motor Neurond

A

Stimulate intrafusal fibers to contract simultaneously with extra feudal fibers stimulated by alpha motor neurons

130
Q

Sensory nerve endings

A

Provide the CNS with continuous information about static muscle length

131
Q

Stretch Reflex

A

Rapid stretch on muscle causes reflex contraction

132
Q

Muscle Spindle Action

A
  1. Muscle spindle detects stretch of the muscle
  2. Sensory neurons conduct action potential to the spinal cord
  3. Sensory neurons synapse with alpha motor neurons
  4. Muscle contracts and resists being stretched
133
Q

GTO

A

Results in reflex relaxation of muscle

Exercise Physiology (3 decks)

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