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Anatomy & Physiology > Muscular System > Flashcards

Muscular System Flashcards

1
Q

Musculoskeletal system

A

an integrated system of bones, muscles, and joints

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2
Q

myology

A

scientific study of muscles

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3
Q

orthopedics

A

the branch of medical science concerned with the prevention or correction of disorders of the musculoskeletal system

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4
Q

overview of muscular tissue

A

40-50% of total body weight is muscular tissue in an average person (depending on body fat, gender, and exercise regimen)

striations

3 types
skeleal
cardiac
smooth

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5
Q

skeletal

A

straited; voluntary

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6
Q

cardiac

A

striated; involuntary

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7
Q

smooth

A

nonstriated; involuntary

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8
Q

4 functions of the musucular system

A

producing body movements
stabilizing body positions
storing and moving substances within the body
producing heat

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9
Q

producing body movements

A

rely on the integrated functioning of skeletal muscles, bones, and
joints

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10
Q

stabilizing body positions

A

skeletal muscles stabilize joints and help maintain body positions;
postural muscles contract continuously when a person is awake

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11
Q

storing and moving substances within the body

A

sphincters in digestive and urinary systems;
cardiac muscle contractions; smooth muscle in walls of blood vessels and digestive system; skeletal muscle to return veinous blood to heart

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12
Q

producing heat

A

heat is produced as muscular tissue contracts; shivering

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13
Q

skeletal muscle tissue

A 
muscle fibers
fascicles
whole muscle
endomysium
perimysium
epimysium
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14
Q

muscle fibers

A

muscle cells; elongated shape

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15
Q

fasicicles

A

bundles of 10-100 or more muscle fibers

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16
Q

whole muscle

A

hundreds to thousands of muscle fibers

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17
Q

endomysium

A

connective tissue that wraps each muscle fiber

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18
Q

perimysium

A

connective tissue that wraps each fasicle

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19
Q

epimysium

A

connective tissue that wraps whole muscle

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20
Q

fascia

A

dense sheet or broad band of dense irregular connective tissue that surrounds muscles; allows free movement, carries nerves, blood vessels, and lymphatic vessels; fills spaces between muscles

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21
Q

subcataneous layer ( hypodermis)

A

separates muscle from skin; composed of areolar connective tissue and adipose tissue; provides pathway for nerves, blood vessels, and lymphatic vessels to enter and exit muscles

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22
Q

tendon

A

a cord of dense regular connective tissue composed of parallel bundles of collagen fibers; an extension of the epimysium, perimysium, and endomysium beyond the muscle

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23
Q

nerve and blood supply

A

Well supplied with both which are directly related to contraction

Prolonged muscle action depends on a rich blood supply to deliver nutrients and oxygen and to
remove wastes

Each skeletal muscle fiber also makes contact with the terminal portion of a neuron

Each fiber is connected to one neuron, each neuron may be connected to 10s, 100s, or 1000s of fibers

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24
Q

proprioceptors are located where

A

throughout the body and inform the brain of the degree of muscle contraction,
the amount of tension on tendons, and the position of joints

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25
Q

muscle spindle cells

A

a specialized muscle fiber type that detects degree of stretch of a muscle;
activation causes contraction of the muscle to prevent damage to the muscle

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26
Q

golgi tendon organs

A

cells located in tendons that detect stretch, or tension on the tendon;
activation causes relaxation of the muscle to prevent damage to the tendon

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27
Q

skeletal muscle tissue histology

A 
sacrolemma
t tubules
multiple nuclei under the sacrolemma
sarcoplasm
contain many mitchondria to produce ATP
consists of thousands of muscle fibers arranged parallel to one another
myoglobin
myofibrils
sarcomeres
sacroplasmic reticulum
z discs
A band
h zone
i band
tropmyosin
alternating darker A bands and lighter I bands give the muscle fiber its striated appearance
tropomyosin
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28
Q

sarcolemma

A

plasma membrane covering each muscle fiber

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29
Q

transverse tubules

A

tunnel in from the surface toward the center of each fiber

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30
Q

sarcoplasm

A

the muscle fiber’s cytoplasm

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31
Q

myoglobin

A

reddish pigment; stores oxygen until it is needed by mitochondria to generate ATP of two types of protein filaments

thin/ thick filaments

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32
Q

thin filaments

A

contain actin, tropomyosin, and troponin; anchored to the Z discs; contains myosin-binding site

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33
Q

thick filaments

A

contain myosin; project myosin heads

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34
Q

sarcomeres

A

basic functional units of striated muscle fibers

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35
Q

sarcoplasmic reticulum

A

a network of fluid-filled membrane-enclosed tubules that stores calcium ions required for muscle contraction

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36
Q

z dics

A

separate sarcomeres from one another; dense protein material

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37
Q

a band

A

darker area within each sarcomere, extends the entire length of the thick filaments

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38
Q

h zone

A

at the center of each A band; narrow; contains only the thick filaments

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39
Q

I band

A

lighter-colored area to either side of the A band; contains the rest of the thin filaments
but no thick filaments

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40
Q

tropomyosin

A

protein; covers the myosin-binding sites on actin

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41
Q

troponin

A

protein; hold tropomyosin in place

When calcium ions bind to troponin, it allows tropomyosin to move off of the myosin binding sites

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42
Q

neuromuscular junction

A

the synapse formed between the axon terminals of a motor neuron and
the motor end plate of a muscle fiber

muscle action potential
motr neuron
motor unit
axon
axon terminals
synaptic end bulbs
motor end plate
synaptic cleft
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43
Q

motor action potential

A

an electrical signal that stimulates a skeletal muscle fiber to contract

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44
Q

motor neuron

A

a neuron that delivers the muscle action potential to a muscle fiber

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45
Q

motor unit

A

a single motor neuron along with all the muscle fibers it stimulates; either all on or
all off; vary greatly in size

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46
Q

axon

A

long process of a motor neuron

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47
Q

axon terminals

A

branches of the axon that approach the sarcolemma of a muscle fiber

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48
Q

synaptic end bulbs

A

the ends of the axon terminals which contain synaptic vesicles filled with a
chemical neurotransmitter

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49
Q

motor end plate

A

the region of the sarcolemma near the axon terminal

50
Q

synaptic cleft

A

the space between the axon terminal and sarcolemma

51
Q

neuromuscular junction- neurotransmitters

A

release of acetylcholine
activation of ACh receptors
generation of muscle action potential
breakdown of ACh

52
Q

release of acetycholine

A

nerve impulse causes neurotransmitter release from synaptic end bulbs that diffuses across synaptic cleft between the motor neuron and motor end plate

53
Q

activation of ACh receptor

A

ACh binds to its receptors in the motor end plate which opens ion channels that allow small cations to flow across the membrane

54
Q

generation of muscle action potential

A

the inflow of cations generates a muscle action potential which travels along the sarcolemma and through the T tubules

55
Q

brakdown of ACh

A

the effect lasts only briefly because ACh is broken down in the synaptic
cleft by an enzyme called acetylcholinesterase

56
Q

sliding filament mechanism

A

the process of muscle contraction by which sarcomeres shorten, causing
the shortening of the muscle fibers

myosin heads of the thick filaments pull on the thin filaments, causing them to overlap and the sarcomere to shorten

length tension relationship

force velocity relationship

57
Q

length tension relationship

A

the precise relationship between myofilament
overlap and tension generation

Tension generation in skeletal muscle is a direct function of the magnitude of overlap
between the actin and myosin filaments

Described at a constant length, not in motion

58
Q

force velocity relationship

A

describes the force generated by a muscle as a function of velocity under conditions of constant load

The velocity of muscle contraction depends on the force resisting the muscle

Describes force generation of moving muscles

59
Q

process of muscle contraction

A

Calcium and ATP are required for muscle contraction

When a fiber is relaxed – low concentration of Ca

When a muscle action potential travels along the sarcolemma into the transverse tubule system,

Ca release channels open, allowing Ca to escape into the sarcoplasm

Ca binds to troponin molecules in the thin filaments, which move the tropomyosin away from the
myosin-binding sites on acting

Cross-bridges are formed with the use of ATP

Power stroke – cross-bridge rotates or swivels
o The cross-bridges remain firmly attached until ATP releases them

60
Q

muscle relaxation

A

relaxation is just the absence of contraction

relaxation occurs when

ACh is rapidly broken down to end the generation of muscle action potentials

Ca ions are rapidly transported from the sarcoplasm into the sarcoplasmic reticulum so the tropomyosin slides back over the myosin-binding sites and the filaments slip back to their relaxed positions

61
Q

muscle tone

A

when a small number of a muscle’s motor units are involuntarily activated to produce a sustained contraction even when the whole muscle is not contracting

keeps skeletal muscles firm, but does not result in movement

flaccid

62
Q

flaccid

A

a state of limpness in which muscle tone is lost (when the motor neurons serving a
skeletal muscle are damaged or cut)

63
Q

energy for contraction

A

the ATP present inside muscle fibers is enough to power contraction for only a
few seconds

64
Q

3 sources for ATP production

A

creatine phosphate
anaerobic cellular respiration
aerobic cellular respiration

65
Q

creatine phosphate

A

about 15 seconds

66
Q

anaerobic cellular espiration

A

2 minutes

after creatine phosphate is depleted, glucose is broken down into
pyruvic acid (which produces 2 ATPs per glucose molecule), then is converted into lactate; occurs without the presence of oxygen
67
Q

aerobic cellular respiration

A

more than 10 minutes

provides energy for activities that last longer than 30 seconds; process that
requires oxygen for ATP to be produced by the mitochondria (produces about 36 ATPs per glucose molecule); occurs with the presence of oxygen

68
Q

while at rest, muscle produce what?

A

ATP than they need; some of the excess is used to make creatine
phosphate (stores P’s to add to ADP to form ATP)

69
Q

muscle fatigue

A

the inability of a muscle to contract forcefully after prolonged activity

lowered release of calcium ions from sacroplasmic reticulum

depletion of creatine phosphate

insufficient oxygen

depletion of glycogen and other nutrients

buildup of lactate and ADP

failure of nerve impulses in the motor neuron to release enough acetylcholine

70
Q

Muscle twitch

A

the contraction that results from a single muscle action potential

71
Q

control of muscle tension

A

Total tension that a single muscle fiber can produce depends on the rate at which nerve impulses arrive

The contraction of a whole muscle depends on the number of muscle fibers that are contracting in unison

72
Q

muscle tension depends on

A

frequency of stimulation

motor unit recruitment

muscle fiber type

73
Q

twitch contraction

A

a brief contraction of all of the muscle fibers in a motor unit in response to a single action potential in its motor neuron

74
Q

myogram

A

recording of a muscle contraction

75
Q

latent period

A

brief delay between application of the stimulus and the beginning of contraction

76
Q

contraction period

A

repetitive power strokes are occurring, generating tension or force of contraction

77
Q

relaxation period

A

power strokes cease because the level of Ca in the sarcoplasm is decreasing to the resting level

78
Q

frequency of stimulation

A

the number of impulses per second

79
Q

wave summation

A

stimuli arriving one after the other before a muscle fiber has completely relaxed causing larger contractions

80
Q

unfused ( incomplete) tetanus

A

a sustained but wavering contraction; the muscle can partially relax between stimuli

81
Q

fused ( complete) tetanus

A

a sustained contraction in which individual twitches cannot be detected; the muscle does not relax at all between stimuli

82
Q

motor unit recruitment

A

the process in which the number of contracting motor units is increased

Asynchronous

Small units give more gradual rise in force for precision

Large units give faster rise in force for strength

Recruited from smallest to largest to avoid fatigue and provide gradual increase in force

83
Q

muscle fiber types

A

slow oxidative/ type I

fast oxidative/ glycolytic / type IIa

fast glycolytic /type IIb

84
Q

slow oxidative/ Type I

A

red; small; contain a large amount of myoglobin; slow twitch; resistant to fatigue, capable of prolonged, sustained contractions

85
Q

fast oxidative / glycolytic / type IIa

A

intermediate size; contain large amount of myoglobin; moderately high resistance to fatigue; contract and relax more quickly than slow oxidative

86
Q

fast glycolytic/ type IIb

A

white fibers; largest in diameter; most powerful and rapid contractions; fatigue quickly; intense movements of short duration

87
Q

how skeletal muscles produce movement

A

cross at least one joint

When the muscle contracts it draws one bone toward the other

The attachment on the stationary bone is the origin

The attachment on the movable bone is the insertion

The fleshy part of the muscle between the tendons is the belly

88
Q

skeletal muscle

A

an organ composed of several types of tissues

skeletal muscle tissue
vascular tissue ( blood vessels and blood)
nervous tissue ( motor neurons)
several types of connective tissues
tendons
89
Q

tendons

A

connect muscle to boen

90
Q

type of muscle actions

A

concentric
eccentric
isometric

91
Q

concentric

A

actively shortening muscle

92
Q

eccentric

A

actively lengthening muscle

93
Q

isometric

A

actively staying the same length

94
Q

agonist ( prime mover)

A

a muscle that causes a desired action

95
Q

antagonist

A

a muscle that has an effect opposite to that of the prime mover

96
Q

synergist

A

a muscle that helps the prime mover function more efficiently by reducing
unnecessary movement

97
Q

stabilizer ( fixator)

A

stabilize the origin of the prime mover so that the prime mover can act more
efficiently

98
Q

skeletal muscle architecture

A

the arrangement of muscle fibers relative to the axis of force generation

parallel/ longitudinal
pennate

99
Q

parallel/longitudinal

A

relatively long with fibers usually going the length of the muscle

flat
sphincter
fusiform
strap
triangular
100
Q

flat

A

parallel fibers, wide fat tendons; i.e. rhomboids, abdominal muscles

101
Q

spinchinter

A

circular muscle to close an opening; i.e. orbicularis oculi

102
Q

fusiform

A

wide in the middle, narrow at the ends; i.e. biceps brachii

103
Q

strap

A

long and thin, may have an intermediate tendon; i.e. rectus abdominis

104
Q

triangular

A

convergent, fan-shaped design often with a spiral; i.e. pectoralis major,
latissimus dorsi, trapezius

105
Q

pennate

A

tendon extends most of the length of the muscle with fibers branching off like a bird’s
feather

unipennate
bipennate
multipennate

106
Q

unipennate

A

diagonal fibers on one side of the long tendon; i.e. vastus lateralis

107
Q

bipennate

A

diagonal fibers branching from both sides of a long tendon; i.e. gastrocnemius

108
Q

multipennate

A

multiple bipennate bellies that form one larger muscle; i.e. deltoid

109
Q

single vs multi joint muscles

A

The design of a muscle is customized for the functional demands placed on it

Crossing multiple joints creates mechanically complex motion possibilities

A muscle can only act on the joints it crosses

110
Q

skeletal muscle and satellite cells

A

In response to muscle inflammation, satellite cells become activated, reproduce, mature, and fuse with damaged muscle fibers to facilitate the remodeling of the damaged muscle fibers

111
Q

satellite cells

A

skeletal muscle stem cells that are critical to muscle regeneration following injury

112
Q

cardiac muscle tissue

A

makes up most of the heart; striated; involuntary

Fibers are branched, shorter in length, larger in diameter, and have a single centrally located nucleus

Intercalated discs

Has endomysium and perimysium, but no epimysium

Autorhythmicity

Several hormones and neurotransmitters can increase or decrease heart rate by speeding or slowing the heart’s pacemaker

Requires a constant supply of oxygen and nutrients

Mitochondria in cardiac muscle fibers are larger and more numerous than in skeletal muscle and produce most of the needed ATP via aerobic cellular respiration

Can use lactate from skeletal muscle fibers to make more ATP during exercise

113
Q

Intercalated discs

A

irregular transverse thickenings of the sarcolemma that interconnect cardiac
muscle fibers

Hold the fibers together and contain gap junctions, which allow muscle action potentials to spread quickly from one cardiac muscle fiber to another

114
Q

Autorhythmicity

A

the built-in intrinsic rhythm of heart contractions initiated by specific cardiac
muscle fibers that act as a pacemaker

115
Q

smooth muscle tissue

A

Found in many internal organs and blood vessels; involuntary; nonstriated (smooth)

Considerably smaller in length and diameter than skeletal; tapered at both ends

Single, oval, centrally located nucleus

Contain thick, thin, and intermediate filaments with no regular pattern of overlap

Contraction is similar to skeletal muscle fibers, but starts more slowly and lasts much longer

Ca ions enter slowly and move out slowly when excitation declines

Smooth muscle tone

Can both shorten and stretch to a greater extent than other muscle types

116
Q

dense bodies

A

functionally similar to Z discs where the thin filaments attach; dispersed
throughout the sarcoplasm and attached to the sarcolemma; attached to bundles of intermediate
filaments

117
Q

2 kinds of smooth muscle tissue

A

visveral

multiunit

118
Q

visceral

A

more common type; found in sheets that wrap around to form part of the walls
of small arteries and veins and hollow viscera

Fibers are tightly bound together in a continuous network

autorhymthmic

119
Q

multiunit

A

consists of individual fibers; in the walls of large arteries, large airways to the lungs, erector pili muscles and internal eye muscles

fibers contract individually
each fiber has its own motor nerve ending

120
Q

smooth muscle tone

A

a state of continuous partial contraction because of the prolonged presence
of Ca ions in the cytosol

Anatomy & Physiology (15 decks)

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