Muscular Tissue Flashcards

1
Q

What percentage of body mass is muscle?

A

40-50%

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2
Q

What are the three types of muscular tissue

A

Skeletal
Cardiac
Smooth

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3
Q

Skeletal Muscle

A

Move bones. Striated with protein bands

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4
Q

Cardiac Muscle

A

Striated. For involuntary action

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5
Q

Smooth muscle

A

Walls of hollow internal structures. Non striated. Involuntary action

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6
Q

4 functions of muscle

A

Produce body movement
Stabalizing body position
Storing and moving substances
Producing heat

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7
Q

4 properties of muscle

A

Electrical excitability
Contractility
Extensibility
Elasticity

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8
Q

Electrical excitability

A

Produce action potentials

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9
Q

Contractility

A

Contract forcefully when stimulated by an action potential

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10
Q

Extensibility

A

Stretch without being damaged

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11
Q

Elasticity

A

Return to original shape

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12
Q

Structure of skeletal muscle

A

Muscle belly connected by tendons to skeleton

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13
Q

Tendons

A

Tough, dense regular connective tissue attaching belly to skeleton

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14
Q

Aponeuroses

A

Tendons arranged in flat sheets

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15
Q

Endomysium

A

Thin wrapping of reticular fibers surrounding muscle fibers

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16
Q

Fasicle

A

Bundles of muscle fibers wrapped in a thicker layer of connective tissue

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17
Q

Perimysium

A

Dense irregular connective tissue covering fasicle

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18
Q

Epimysium

A

Thicker, dense irregular connective tissue covers perimysium and binds fascicles together to form muscle belly

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19
Q

Fascia

A

Dense irregular sheets protecting groups of skeletal muscle

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20
Q

Neurovascular Bundle

A

Nerves and blood vessels enter muscle near tendon attachment

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21
Q

Myoblast

A

Skeletal muscle fiber arises from fusion of myoblasts

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22
Q

Sattelite cells

A

Myoblasts remaining in mature skeletal muscle help regenerate damaged tissue

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23
Q

Fibrosis

A

Replacement of muscle tissue by fibrous scar tissue

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24
Q

Sarcolemma

A

Plasma membrane of muscle fiber

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25
Q

Transverse tubule

A

Thousands of tiny holes in sarcolemma tunnel towards center of transmit action potentials

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26
Q

Sarcoplasm

A

Cytoplasm of muscle fibers release glycogen for production of ATP

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27
Q

Myoglobin

A

Only in muscles. Binds oxygen molecules that diffuse into muscle fibers

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28
Q

Myofibrils

A

Little contractile threads in sarcoplasm

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29
Q

Sarcoplasmic Reticulum

A

System of fluid filled sacs surround each myofibril

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30
Q

Terminal Cisterns

A

Dilated end sacs of sarcoplasmic reticulum butt against either end of a transverse tubule

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31
Q

Triad

A

One transverse tubule and two terminal cisterns on either end

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32
Q

What triggers muscle contraction?

A

When triggered terminal cisterns release Ca into sarcoplasm

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33
Q

Filaments

A

Small protein structures within myofibrils are involved in contractile process

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34
Q

Sarcomeres

A

Basic functional unit of myofibril

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35
Q

Z- Discs

A

Dense protein plates seperate sarcomeres

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36
Q

A- Band

A

Dark middle part of sarcomere extends entire length of thick filaments

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37
Q

Zone of overlap

A

End of A- band where thick and thin filaments lay side by side

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38
Q

I- Band

A

Less dense area containing only thin filaments

Z- disc passes through centre

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39
Q

H- Zone

A

Centre of each A- Band contains only thick filaments

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40
Q

M- Line

A

Supporting proteins hold thick filaments together at middle of the sarcomere

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41
Q

3 kinds of proteins composing myofibrils

A

Contractile
Regulatory
Structural

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42
Q

Contractile proteins

A

Generate force

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43
Q

Regulatory proteins

A

Switch contractions on and off

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44
Q

3 functions of Structural proteins

A

Keep filaments in alignment
Give myofibril extensability/ elasticity
Link myofibrils to sarcolemma

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45
Q

2 contractile proteins

A

Myosin

Actin

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46
Q

Myosin

A

Motor protein that composes thick filaments. Looks like 2 twisted gold clubs

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47
Q

Motor proteins

A

Convert ATP’s chemical energy into mechanical energy

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48
Q

Which way to the myosin tails point?

A

Toward the M- Line

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49
Q

Actin

A

Composes thin filaments. Twisted into a helix

50
Q

Where do thin filaments extend from?

A

Z- disc

51
Q

Myosin binding site

A

Area on actin where myosin head attaches

52
Q

2 regulatory proteins

A

Tropomyosin

Troponin

53
Q

4 primary structural proteins

A

Titin
Myomesin
Nebulin
Dystrophin

54
Q

Titin

A

Spans half of sarcomere from Z- disc to M- Line and anchors thick filaments

55
Q

Myomesin

A

Form the M- Line and hold thick filaments in alignment

56
Q

Nebulin

A

Anchor thin filaments to Z- Disc

57
Q

Dystrophin

A

Links thin filaments to sarcolemma to reinforce it

58
Q

Sliding Filament Mechanism

A

Skeletal muscle shortens during contraction as thick and thin filaments slide past one another

59
Q

How does the sarcomere shorten?

A

Myosin heads walk up thin filaments pulling them towards the M- line

60
Q

Neuromuscular Junction

A

Synapse between a motor neuron and a skeletal muscle fiber where muscle action potentials arise

61
Q

What happens before the Contraction cycle can begin?

A

Ca ions released which binds to Troponin

Troponin moves Tropomyosin away from myosin binding sites on actin

62
Q

What structure releases Ca ions?

A

Sarcoplasmic reticulum

63
Q

4 stages of Contraction cycle?

A

ATP hydrolysis
Cross bridge
Power stroke
Detachment of myosin from actin

64
Q

ATP hydrolysis

A

Myosin head has an ATP binding site and ATPase which breaks it down ADP to reenergize the myosin head

65
Q

Cross Bridge

A

Myosin head attaches to actin and releases phosphate group

66
Q

Power Stroke

A

Site on cross bridge where ADP is bound opens. Bridge rotates and releases ADP so sarcomere contracts

67
Q

Synapse

A

Region of communication between two neurons

68
Q

Synaptic Cleft

A

Gap between cells that action potential must jump

69
Q

Axon terminal

A

End of motor neuron

70
Q

What is the neural component of NMJ?

A

Synaptic end bulbs

71
Q

Synaptic vesicles

A

Membrane enclosed sacs within each synaptic end bulb

72
Q

What is the neurotransmitter released at NMJ?

A

Actylcholine (ACh)

73
Q

What is the muscular component of NMJ?

A

Motor end plate

74
Q

Acetylcholine receptors

A

Transmembrane proteins bind to ACh

75
Q

4 steps in producing muscle action potential

A

Release ACh
Activation of ACh receptors
Produce muscle action potential
Breakdown of ACh

76
Q

Muscle tone

A

Weak, involuntary contractions of motor units

77
Q

What causes muscle tone?

A

Neurons in brain and spinal cord excite somatic motor neurons

78
Q

Isotonic Contractions

A

Tension remains constant while muscle length changes. Body movements and moving objects

79
Q

Concentric Isotonic Contraction

A

Tension is great enough to overcome load. Muscle shortens and pulls at tendon to reduce angle at joint

80
Q

Eccentric Isotonic Contraction

A

Length of muscle increases during contraction

81
Q

What type of isotonic contraction produces more muscle damage?

A

Eccentric

82
Q

Isometric Contraction

A

Tension generated is not great enough to exceed object being moved . Muscle does not change in length.

83
Q

Which type of contraction is important for posture?

A

Isometric

84
Q

Red muscle fibers

A

High in myoglobin

85
Q

White muscle fibers

A

Low in myoglobin

86
Q

What type of skeletal fiber is white?

A

Fast glycolytic fibers

87
Q

3 types of skeletal muscle fibers

A

Slow oxidative
Fast oxidative- glycolytic
Fast glycolytic

88
Q

Slow oxidative fibers

A

Red muscle fibers produce ATP aerobically. Slow contraction but very resistant to fatigue

89
Q

What contributes to how fast muscle fibers contract?

A

How fast the ATPase in the myosin head hydrolyzes ATP

90
Q

Fast oxidative- glycolytic fibers

A

Red muscle fibers produce ATP both aerobically and anaerobically. Faster contraction and resistance to fatigue

91
Q

Fast glycolytic fibers

A

White muscle fibers produce ATP anaerobically. Contract very strongly and quickly but fatigue quickly

92
Q

What fibers does aerobic exercise change?

A

FG to FOG

93
Q

What percentage of muscle mass is lost between age 30-50?

A

10%

94
Q

What percentage of muscle mass is lost by age 80?

A

50%

95
Q

What is muscle tissue replaced with as you age?

A

Fibrous connective tissue and adipose tissue

96
Q

What fibers increase as you age?

A

Slow oxidative fibers

97
Q

Authorhythmicity

A

Natural pacemaker initiates each cardiac and smooth muscle contraction

98
Q

Which muscle type is subject the most amount of stretching

A

Smooth

99
Q

What are tendons made of

A

Parallel arrangements of collagen fibers

100
Q

Function of endomysium

A

Carries small blood vessels that supply muscle fibers with nutrients

101
Q

How do neuromuscular bundles spread through the muscle

A

Connective tissue channels formed by the perimysium and endomysium as they wrap the muscle cells

102
Q

Motor fibers

A

Part of neuromuscular bundle that initiates contractile function of muscle cells

103
Q

Sensory fibers

A

Part of neuromuscular bundle that provides feedback to the nervous system to regulate motor function

104
Q

Somatic Motor Neurons

A

Neurons that stimulate skeletal muscle fibers to contract

105
Q

Axon

A

Threadlike extension of a motor neuron travels from muscle cell body to spinal cord

106
Q

When does the muscle fiber lose its ability to undergo cell division

A

After fusion of the myoblasts

107
Q

What are transverse tubules filled with

A

Interstitial fluid

108
Q

Where are the Ca ions when the muscle fiber is relaxed

A

Sarcoplasmic reticulum

109
Q

Where are the Ca ions when the muscle fiber is triggered

A

Sarcoplasm

110
Q

Ratio of thick and thin filaments

A

2 thin for every thick filament in regions of overlap

111
Q

Striations

A

Patterns of overlap consisting of a variety of zones and bands

112
Q

When is mysosin blocked from binding site by tropomyosin

A

When muscle is relaxed

113
Q

Synaptic end bulbs

A

Axon terminal divides into a cluster of synaptic end bulbs

114
Q

Where is ACh stored

A

Inside synaptic vesicles

115
Q

Motor end plate

A

Region of sarcolemma opposite the synaptic end bulbs

116
Q

Where are the ACh receptors

A

In the motor end plates

117
Q

Junction Folds

A

Deep grooves in the motor end plate that provide a large surface area for ACh

118
Q

Motor unit

A

Somatic motor unit plus all the skeletal muscle fibers it stimulates

119
Q

What is stimulated by the arrival of a nerve impulse at the synaptic end bulb

A

Channels open and Ca ions enter synaptic end bulbs

120
Q

Strength Trianing

A

Exercising with progressively higher resistance to strengthen the musculoskeletal system

121
Q

Intercalated discs

A

Ends of cardiac muscle fibers connect to neighboring fibers by a thickening in sarcolemma

122
Q

What two cell junctions do intercalated discs have

A

Gap junctions

Desmosomes