Musculoskeltal System Flashcards
1
Q
The Human Body Contains How many Skeletal Miscles
A
Greater Than 600
2
Q
What are the 4 Functions of Skeletal Muscle
A
- Force production for locomotion and breathing
- Force Production for Posture Support
- Heat Production during cold stress
- Endocrine organ that plays a role in regulating other organ systems
3
Q
Flecked
A
Decrease joint angle
4
Q
Extensions
A
Increase joint angle
5
Q
The connective Tissue Covering Skeletal Muscle
A
- epimysium
- Perimysium
- Endomysium
- Basement Membrane
- Sarcolemma
6
Q
Epimysium
A
Surrounds entire muscle
7
Q
Perimysium
A
Surrounds bundles of muscle fibers
8
Q
Fascicles
A
Bundles of muscle fibers
9
Q
Endomysium
A
Surrounds individual muscle fibers
10
Q
Basement Membrane
A
Just below endomysium providing another protective layer
11
Q
Sarcolemma
A
Muscle cell membrane that surrounds the muscle fiber
12
Q
Satellite cells play a role
A
in muscle growth and repair
13
Q
Strength Training causes growth enhancement by
A
Dividing and increasing the number of nuclei to the existing muscle fiber
14
Q
More Nuclei Allow for
A
Greater protein synthesis for muscle growth
15
Q
Myonuclear domain
A
The volume of cytoplasm surrounding each nucleus
16
Q
Each nucleus can support
A
A limited myopic lead domain
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
18
Q
Beneath the sarcolemma lies the
A
Sarcoplasm which contains cellular proteins organelles and myofibrils
19
Q
Myofibrils
A
Contain contractile proteins - actin and myosin
20
Q
Actin
A
Thin filament - contain the proteins troponin and tropomyosin which play a key role in the contractile process
21
Q
Myosin
A
Thick filament
22
Q
Sarcomere (subdivision of a myofibril)
A
Includes:
- Z line
- M line
- H zone
- A band
- I band
23
Q
Z line
A
Divided each sarcomere
24
Q
M line
A
The fine line in the middle of the H zone
25
H zone
Myosin filament with no overlap of actin located in the center of a sarcomere
26
A band
Dark portion of a sarcomere where myosin filaments are located
27
I band
Light region of the sarcomere where actin is primarily located
28
Sarcoplasmic Reticulum
1. Membranous channels that surround each myofibril
2. Storage site for calcium
3. Terminal Cisternae (lateral sacs) enlarged portion of SR
29
Transverse Tubules
Extend from sarcolemma to SR and runs completely through the muscle fiber. Lies between the terminal Cisternae.
30
Neuromuscular Junction
Is the junction between the motor neuron and muscle fiber
31
Motor Unit
Motor neuron and all fibers it innervates
32
Motor Neurons extends
Outward from spinal cord
33
Motor end plate
Pocket formed around motor neuron by sarcolemma
34
Neuromuscular Cleft
Short gap between neuron and muscle fiber
35
Synaptic Cleft
Neuromuscular Cleft
36
Acetylcholine is released from
The motor neuron
37
Acetylcholine causes
An increase in the permeability of the sarcolemma to sodium which results in an end plate potential - depolarization of muscle
38
End Plate Potential
Muscle depolarization
39
The sliding Filament Model
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
40
Power Stroke
Formation of cross bridges between actin and myosin filaments
41
Swinging lever arm model
Sliding filament model
42
Calcium binding to troponin causes
Tropomyosin to be removed from the active binding site on actin leading to cross bridge attachment
43
ATP is required for
Muscle contraction
44
Myosin ATPase
Breaks down ATP as fibers contract
45
Myosin ATPase is located
On the head of the myosin cross bridge
46
ATP breakdown leads to
Muscle shortening by energizing myosin cross bridges
47
EC coupling
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
48
Excitation
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
49
Contraction
4. Depolarization of T-Tubules causes release of calcium from the SR
5. Calcium binds to troponin causing a shift in tropomyosin to uncover myosin binding sites on actin
6. Myosin binds to actin to form cross bridges
7. Pi is released from myosin and cross bridge movement occurs
8. New ATP attaches to myosin breaking the cross bridge. Then ATP is broken down which energizes myosin
50
Relaxation
9. Motor Neuron Stimulation ends, Ach is no longer released and muscle fibers repolarizes
10. Calcium is pumped back into SR and tropomyosin returns to original position covering myosin binding sites on actin and muscle relaxation occurs
51
Cross Bridges Require
ATP
52
After the inorganic phosphate leaves the cross bridge the myosin head moves producing the
Power stroke
53
Muscle Fatigue
A decline in muscle power output by a decrease in force generation and a decrease in shortening velocity
54
Muscle fatigue is caused by
Disturbances in the CNS and peripheral factors within skeletal muscles
55
CNS fatigue from long duration exercise
A decrease in excitatory neurotransmitters in the motor cortex reduces motor neuron activation to skeletal muscle.
56
Current Research Suggests that fatigue is due to both
Central and peripheral factors
57
Peripheral Factors related to muscle fatigue
Peripheral factors disrupt cross bridge formation at high intensity ( ~60 seconds) and long duration (2-4 hours)
58
High intensity exercise leads to muscle fatigue when
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
Long Duration Exercise leads to muscle fatigue when
There is an accumulation of free radicals, an electrolyte imbalance or glycogen depletion
60
Source of ATP
Oxidative Phosphorylation
PC-ATP system
Glycolysis
61
Fatigue is characterized by
A reduction in muscle force production and a decreased contraction time
62
Muscle Cramps Are
Spasmodic involuntary muscle contractions
63
Two theories of muscle cramps
Electrolyte and dehydration theory
| And the altered neuromuscular control theory
64
Electrolyte depletion and dehydration theory
Water and sodium loss via sweating causes spontaneous muscle contraction which causes motor nerve terminals to spontaneously discharge
65
Altered neuromuscular control theory
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
Muscle cramps can be relieved by
Passive stretching
67
Passive stretching relieves cramps by
Stretching activates Golgi tendon organs which inhibit motor neurons in the spinal cord resulting in muscle relaxation
68
Inverse stretch reflex
Stretching activates Golgi tendon organs which inhibit motor neurons in the spinal cord resulting in muscle relaxation
69
Inverse stretch reflex provides support
That impaired neuromuscular control is present in exercise induced muscle cramping
70
Percentage o fiber types in skeletal muscle is related to
Genetics, blood levels of hormones and the exercise habits of the individual
71
Biochemical properties of skeletal muscle
Oxidative Capacity
Type of Myosin ATPase
Abundance of contractile proteins within the fiber
72
Oxidative Capacity
Number of capillaries, mitochondria and amount of myoglobin
Fatigue resistance
73
Type of Myosin ATPase
Speed of ATP degradation
| Results in high speed of muscle shortening
74
High ATPase activity
High ATP breakdown capability
75
Abundance of contractile proteins within the fiber
Large amounts of actin and myosin relate to being able to produce more force
76
Contractile Properties of skeletal Muscle
1. Maximal Force Production
2. Speed of Contraction
3. Maximal Power Output
4. Muscle Fiber Efficiency
77
Maximal Force Production
Force per unit of cross sectional area
78
Speed of contraction
Myosin ATPase activity
79
Vmax is determined by
The rate of cross bridge cycling
80
Maximal Power Output
Determined by force generation and shortening velocity
81
Muscle Fiber Efficiency
Measure of muscle fiber economy
- the less ATP used to produce a greater force the more efficient it is
82
Muscle Fiber Efficiency Formula
ATP uses/Forced Produced
83
Muscle Biopsy
Small piece of muscle is removed
84
Staining for types of myosin ATPase
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
Immunogistological staining
Selective antibody binds to a unique myosin proteins fiber types are differentiated by color difference
86
Gel electrophoresis allows you to identify
Myosin isoforms specific to different fibers types
87
Dystrophin
Protein in sarcolemma
88
Type 1 fibers
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
Type IIa
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
Type IIx
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
Type 1 fibers have less
Contractile proteins than type 2 for a specific area
92
Fast fibers exert more force
Than type 1 fibers because they contain more myosin cross bridges per cross sectional area
93
Type 1 fibers have low Vmax capabilities
Due to low myosin ATPase activity
94
Non-athletes have
Half slow and half fast fibers
95
Power athletes
Have a high percentage of fast fibers
96
Endurance athletes have
A higher percentage of slow fibers
97
Muscle Action Describes
The process of force development
98
Isometric action
Static exercise
The muscle exerts force with out changing length
99
Examples of isometric action
Pulling against an immovable object
Postural muscles during sitting or standing
100
Dynamic action
Isotonic exercise
Can be concentric or eccentric
101
Concentric action
Muscle shortens during force production
102
Eccentric Action
Muscle produces force but length increases
103
Eccentric action is associated with
Muscle fiber injury and delayed onset muscle soreness
104
Muscle Twitch
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
Speed of shortening is greater in
Fast fibers because
SR releases Calcium at a faster rate and higher ATPase activity
106
Force exerted during muscle contraction is dependent on 3 factors
Type and number of motor units recruited
Initial muscle length
Nature of the neural stimulation of motor units
107
Types and number of motor units recruited
More motor units = greater force
More Fast Motor Units = greater force
108
Initial muscle length
Increased cross bridge formation at ideal length
109
Neural stimulation
Simple twitch
Summation
Tetanus
110
Summation
Addition of successive twitches causes increased force
111
Tetanus
Increasing stimuli so rapidly so that the individual contractions blend into a single sustained contraction
112
As the frequency of neural stimulation increases
The force developed increases
113
Force velocity relationship
At any absolute force the speed of movement is greater in muscles with higher percentages of fast twitch fibers
114
The maximum velocity of shortening is greatest
at the lowest force
115
The peak power increases with velocity up to movement spee doc
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
Mykonos
Small signaling molecules released by skeletal muscle. They act as hormones or hormone messengers that affect a variety of other tissues
117
Skeletal muscle produces my planes when it
Contracts stimulating glucose uptake and fatty acid oxidation
Promoting blood vessel growth in muscle
Promoting liver glucose production and TGA breakdown
118
IL-6
Principle myofibril produced during exercise
Pro and anti inflammatory
Inhibits TNF a and other antionflammatories
119
Regular exercise
Promotes antionflammatory environment
120
Proprioceptors
Provide CNS with information about body position
They are located in joints and muscles
121
Kinesthesia
Related to conscious recognition of the body parts with respect to one another and to limbs movement rates
122
Joint Propioceptors
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
Muscle Proprioceptors
Provide sensory feedback to the nervous system concerning relative muscle length and tension development by muscle
1. Muscle spindle
2. Golgi tendon organ
124
Muscle Spindle
Respond to changes in muscle length that require the finest degree of control
125
Muscle spindles consist of
Intrafusal Fibers
Gamma Motor Neurons
Sensory Nerve Endings
126
Intrafusal Fibers
Run parallel to normal muscle fibers and insert into connective tissue with in muscles
127
Intrafusal fibers are composed of
Several thin muscle cells
128
Extrafusal Fibers
Normal muscle fibers
129
Gamma Motor Neurond
Stimulate intrafusal fibers to contract simultaneously with extra feudal fibers stimulated by alpha motor neurons
130
Sensory nerve endings
Provide the CNS with continuous information about static muscle length
131
Stretch Reflex
Rapid stretch on muscle causes reflex contraction
132
Muscle Spindle Action
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
GTO
Results in reflex relaxation of muscle
