Chapter 9 - Muscles Flashcards

1
Q

What is myology?

A

The scientific study of muscles.

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2
Q

What mass of the body is muscle?

A

45%.

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3
Q

Functions of muscle?

A

Maintain posture and body position, movement, heat production, guard orifices, and support visceral organs.

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4
Q

Muscle tissue is?

A

Excitable, extensible, elastic, and contractile.

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5
Q

What does excitability mean?

A

The ability to receive and respond to electrical or chemical stimuli.

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6
Q

What does contractility mean?

A

The ability to shorten forcibly when stimulated.

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7
Q

What does elasticity mean?

A

The ability to return to original shape after being stretched.

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8
Q

What does extensibility mean?

A

The ability to be stretched without damaging the tissue.

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9
Q

Are muscles organs?

A

Yes.

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10
Q

What do muscles consist of?

A

Connective tissue, arteries/veins nerves, lymphatics, and contractile muscle cells.

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11
Q

Characteristics of skeletal muscle?

A

Attaches to bone, skin or fascia, striated with light & dark bands, voluntary control, long, thin and multi-nucleated fibers, attach to and cover bony skeleton, contracts rapidly, but tires easily, and may exert great force.

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12
Q

1 muscle cell equals?

A

Fiber.

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13
Q

What is the belly of the muscle?

A

Main portion of a muscle.

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14
Q

Where does the belly attach?

A

Tendons.

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15
Q

Tendons attach to what?

A

Bone.

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16
Q

What is deep fascia?

A

Dense irregular CT around muscle, holds it in place and separates it from other muscles.

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17
Q

What is subcutaneous fascia?

A

Loose CT beneath skin, surrounds several muscles.

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18
Q

What is superficial fascia?

A

Areolar and adipose tissue layer and sits deep to cutaneous membrane.

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19
Q

What are many muscle fibers bundled together into groups called?

A

Fascicles.

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20
Q

Characteristics of fascicles?

A

10-100 muscle cells (fibers), several fasicles make up a muscle.

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21
Q

What are the connective tissues of skeletal muscle?

A

Epimysium, perimysium, and endomysium.

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22
Q

What is epimysium?

A

Surrounds the whole muscle.

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23
Q

What is perimysium?

A

Surrounds fascicles.

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24
Q

What is endomysium?

A

Separates individual muscle fibers (cells).

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25
Q

All connective tissue extend beyond the muscle belly forming?

A

Tendon.

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26
Q

What is a tendon that is a thick flattened sheet?

A

Aponeuroses.

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27
Q

What are myoblasts?

A

Embryonic cells that fuse to form muscle fibers.

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28
Q

What are myosatellite cells?

A

Myoblast that do not fuse.

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29
Q

What do myosatellite cells do?

A

Assist in repair of damaged cells.

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30
Q

What are muscle fibers composed of?

A

Sarcoplasm, Sarcolemma, and Transverse (T) tubules.

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31
Q

What is sarcoplasm?

A

Fiber cytoplasm.

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32
Q

What is sarcolemma?

A

Plasma membrane of a fiber.

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33
Q

What are transverse (T) tubules?

A

Extensions of the sarcolemma into the sarcoplasm.

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34
Q

What are myofibrils?

A

Contractile organelles that extend the length of fiber and surrounded by sarcoplasmic reticulum.

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35
Q

What is a functional unit of a myofibril?

A

Sarcomere.

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36
Q

What are sarcomeres made of?

A

Thick and thin filaments.

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37
Q

What are thick filaments composed of?

A

Myosin.

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38
Q

Myosin characteristics?

A

Twisted protein with globular heads, 1.6um long, and 500/thick filament.

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39
Q

What are thin filaments composed of?

A

Actin and Regulatory proteins.

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40
Q

Actin characteristics?

A

Structural protein and coiled “beads”

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41
Q

Regulatory protein characteristics?

A

Allow/prohibit attachment between actin and myosin.

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42
Q

What are the 2 types of regulatory proteins?

A

Tropomyosin and troponin.

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43
Q

These cause the striated appearance?

A

Sarcomere “bands”.

44
Q

What are the types of sarcomere bands?

A

A bands, I bands, H bands, and zone of overlap.

45
Q

A band?

A

Entire thick filament range.

46
Q

I band?

A

Only thin filaments.

47
Q

H band?

A

Only thick filaments.

48
Q

Zone of overlap?

A

Both filaments.

49
Q

These divide and flank the sarcomere?

A

Sarcomere “lines”.

50
Q

Types of sarcomere lines?

A

Z line and M line.

51
Q

Z line?

A

The end of the sarcomere, made of actinin protein, and anchor thin filaments.

52
Q

M line?

A

Middle of the sarcomere and stabilize thick filaments.

53
Q

What are the types of structural proteins?

A

Titin, Nebulin, and Actinin.

54
Q

What does titin do?

A

Anchors a thick filament to a Z line and accounts for elasticity and extensibility.

55
Q

What does nebulin do?

A

Holds F actin together on thin filaments.

56
Q

What does actinin do?

A

Makes up Z line.

57
Q

What is the sliding filament theory?

A

Actin sliding over the myosin.

58
Q

What happens as actin slides over myosin?

A

Zone of overlap enlarges, H band shrinks, I band shrinks, A band remains the same, and the Z line moves closer to the A band.

59
Q

What comprise the neuromuscular junction?

A

motor unit, synaptic terminal, motor end plate, synaptic cleft, and neurotransmitter.

60
Q

What is the neuromuscular junction?

A

The point of contact between the neuron and the muscle.

61
Q

How is the tension produced by a muscle determined?

A

The frequency of stimulation and number of motor units stimulated.

62
Q

What is the All-or-None law?

A

All fiber in a motor unit fully contract if stimulated.

63
Q

What is recruitment?

A

Steady increase in tension by increasing the number of contracting motor units.

64
Q

What is tetanus?

A

Muscle never begins to relax, continuous fused contraction.

65
Q

What is muscle tone?

A

Motor units contract randomly and tension, but no movement.

66
Q

What can muscle tone do?

A

Stabilize joints, hold objects in place, and maintain posture.

67
Q

What is hypertrophy?

A

Constant, exhaustive stimulation increases the number of organelles/ proteins in a fiber and overall enlargemtn of the muscle.

68
Q

What does hypertrophy increase?

A

Mitochondria, glycolytic enzyme reserves, myofibrils, filaments within myofibrils.

69
Q

Do muscle fibers reproduce?

A

No.

70
Q

What is atrophy?

A

Lack of constant motor neuron stimulation reduces organelles and proteins.

71
Q

What causes atrophy?

A

Age, hormones, lack of use, and nerve damage.

72
Q

Is muscle atrophy reversible?

A

Yes, if the fiber is not dead.

73
Q

What is the origin of a muscle?

A

Attachment site that does not move.

74
Q

What is the insertion of a muscle?

A

Attachment site that moves.

75
Q

Parallel muscle characteristics and example?

A

Fasicles parallel to long axis and unidirectional force. Biceps brachii.

76
Q

Convergent muscle characteristics and example?

A

Fan shaped, multidirectional force, versatility, and generates least amount of force. Pectoralis major.

77
Q

Pennate muscle characteristics and example?

A

Feather-shaped, fascicles oblique to long axis, tendon passes through muscle, and greatest force. Deltoid.

78
Q

Circular muscle characteristics and example.

A

Concentric fascicles around openings, and contraction decreases lumen diameter. Orbicularis oculi.

79
Q

What is uniaxial and movements?

A

Rotation around one axis. Rotation (atlanto-axial and pivot joints) Angular (Knee and interphalangeal joints).

80
Q

What is biaxial and movements?

A

Movement occurs along 2 axes. Angular motion: flexion/extension and abduction/adduction.

81
Q

What is multiaxial and movements?

A

Movement on all axes. Angular motion : flexion/extension and abduction/adduction, rotation and circumduction.

82
Q

Events of muscle contraction?

A

Ach stored in synaptic vesicles, Ach released, Ach crosses gap & binds to receptors, impulse travels through motor end plate down T tubule to SR Ca2+ diffuse into sarcoplasm, Ca2+ exposes active site, myosin binds, ATP is used and contraction occurs, and contraction keeps occuring as long as Ca2+ concentration is high.

83
Q

Events of muscle relaxation?

A

Ach decomposed by AChE, Ca2+ transported back to SR, actin & myosin links broken, cross-bridges move back, and active site is blocked once again.

84
Q

Types of muscle action?

A

Agonist, antagonist, synergist and fixator.

85
Q

What does agonist mean?

A

Main muscle causing directional force.

86
Q

What does antagonist mean?

A

Muscle that contracts to oppose agonist.

87
Q

What does synergist mean?

A

Muscle that assists/ modifies movement.

88
Q

What does fixator mean?

A

Muscle that stabilizes elements associated with agonist.

89
Q

Levers can change what?

A

Magnitude of force, speed, direction, distance of limb movement.

90
Q

What are the components of lever system?

A

Lever (L) = skeletal element
Effort (E) = applied force (AF)
Fulcrum (F) = joint
Resistance (R) = body part or object moved.

91
Q

Types of levers?

A

First class, second class, and third class.

92
Q

What is a first class lever?

A

See-saw, R opposite of E with F central.

93
Q

What is a second class lever?

A

Wheel-barrow, E opposite of F to move R.

94
Q

What is a third class lever?

A

Shovel, E in between F and R.

95
Q

What are the types of skeletal muscle fibers?

A

Fast fibers, slow fibers, and intermediate fibers.

96
Q

Fast fiber characteristics?

A

Fast acting, high energy requirement, anaerobic, large diameter, densely packed myofibrils, large glycogen reserves, few mitochondria, and rapid, powerful brief contractions (light color).

97
Q

Slow fiber characteristics

A

More myoglobin. slower sustained contraction, aerobic, small diameter, longer to contract, and contract for longer time (dark color).

98
Q

Intermediate fiber characteristics?

A

Attributes of both, similar to fast fibers, greater resistance to fatigue, and exercise or lack of can change one muscle type to another.

99
Q

Smooth muscle characteristics?

A

Attached to hair follicles in skin, in walls of hollow organs & BVs, nonstriated, involuntary control, contractions are slow and sustained, spindle shaped, very elastic, and resistant to fatigue.

100
Q

Smooth muscles are stimulated by?

A

Nervous system, hormones, ions, stretching.

101
Q

Types of smooth muscle?

A

Single-unit and multi-unit.

102
Q

Single-unit characteristics and examples?

A

Many gap junctions, sheets of spindle-shaped cells, contracrt together BVs, digestive, respiratory, and urinary tracts.

103
Q

What is the term for contracts together?

A

Syncytial contraction.

104
Q

Multi-unit characteristics and examples?

A

No or few gap junctions, separate fibers, contract independently, and only contract when stimulated by motor nerve. Walls of large BVs, uterus, and iris of eye.

105
Q

Cardiac muscle characteristics?

A

Striated in appearance, involuntary control, autorhythmic, network of fibers with intercalated disks at ends, and found only in heart.