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A&P I Lecture > Chapter 9 (I) > Flashcards

Chapter 9 (I) Flashcards

1
Q

muscle tissue transforms ___(1)___ to ___(2)___ to exert force.

A

(1) chemical energy (ATP)

(2) mechanical energy

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2
Q

what are the 3 types of muscle tissue?

A

skeletal, cardiac, and smooth

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3
Q

skeletal muscles attach to ___(1)___ and ___(2)___.

A

(1) bones

(2) skin

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4
Q

muscle fibers

A

elongated cells

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5
Q

which muscles are striated, voluntary, contract rapidly, and tire easily?

A

skeletal muscles

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6
Q

which muscles require nervous system stimulation?

A

skeletal muscles

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7
Q

which muscles are only in the heart and are the bulk of heart walls?

A

cardiac muscles

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8
Q

which muscles are striated, involuntary, and can contract without nervous system stimulation?

A

cardiac muscles

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9
Q

which muscles are found in walls of hollow organs such as the stomach, urinary bladder, and airways?

A

smooth muscle

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10
Q

which muscles are not striated, involuntary, and can contract without nervous system stimulation?

A

smooth muscle

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11
Q

cell shape and appearance of ______: single, very long, cylindrical, multinucleate cells with obvious striations.

A

skeletal muscle cells

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12
Q

cell shape and appearance of ______: branching chains of cells; uni- or binucleate; striations.

A

cardiac muscle cells

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13
Q

cell shape and appearance of ______: single, fusiform, uninucleate; no striations.

A

smooth muscle cells

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14
Q

connective tissue components of skeletal muscles?

A

epimysium, perimysium, and endomysium

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15
Q

connective tissue components of cardiac muscle?

A

endomysium attached to fibrous skeleton of heart

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16
Q

what are the connective tissue components of smooth muscle?

A

endomysium

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17
Q

which muscles have the presence of myofibrils composed of sarcomeres? which muscles have the presence of T tubules?

A

skeletal and cardiac

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18
Q

where is the site of invagination of T tubules in the skeletal muscles? cardiac muscles?

A

skeletal:
2 in each A-I junction
cardiac:
1 in each sarcomere of Z disc

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19
Q

which muscle is the most organized? least organized?

A

most organized: skeletal

least organized: smooth

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20
Q

what has the most elaborate sarcoplasmic reticulum?

A

skeletal muscle

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21
Q

which muscles have the presence of gap junctions?

A

cardiac and smooth muscle

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22
Q

how do skeletal muscles regulate contractions?

A

voluntary contractions via axon terminals of the somatic nervous system

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23
Q

how do cardiac muscles regulate contractions?

A

involuntary
intrinsic system regulation and autonomic nervous system controls
hormones

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24
Q

how do smooth muscles regulate contractions?

A

involuntary
autonomic nerves
hormones
local chemicals

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25
Q

source of calcium for calcium pulse for skeletal, cardiac, and smooth muscle?

A

skeletal: sarcoplasmic reticulum (SR)

cardiac and smooth: SR and extracellular fluid

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26
Q

what is the site of calcium regulation for skeletal, cardiac, and smooth muscle?

A

skeletal and cardiac: troponin on actin-containing thin filaments
smooth: calmodulin in cytosol

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27
Q

which muscles have the presence of a pace maker?

A

cardiac and smooth

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28
Q

what are the effects of nervous system stimulation for skeletal, cardiac, and smooth muscle?

A

skeletal: excitation

cardiac and smooth: excitation or inhibition

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29
Q

speed of contraction for skeletal, cardiac, and smooth?

A

skeletal: slow to fast
cardiac: slow
smooth: very slow

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30
Q

which muscles have rhythmic contractions?

A

cardiac and smooth (in unitary muscle)

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31
Q

what kind of respiration does each muscle partake in?

A

skeletal: aerobic and anaerobic
cardiac: aerobic
smooth: mainly aerobic

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32
Q

what are the special characteristics of muscle tissue?

A

excitability
contractility
extensibility
elasticity

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33
Q

excitability

A

receive/respond to stimuli

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34
Q

contractility

A

ability to shorten forcibly when stimulated

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35
Q

extensibility

A

ability to be stretched

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36
Q

elasticity

A

ability to recoil to resting length

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37
Q

4 important functions of muscles

A

move bones/fluids
maintain posture/body position
stabilize joints
heat generation

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38
Q

what are the additional functions of muscle?

A

protect organs
forms valves
controls pupil size
cause goosebumps

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39
Q

which muscle is served by 1 artsy, 1 nerve, and 1/more veins?

A

skeletal muscle

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40
Q

where do arteries, nerves, and veins enter/exit through in skeletal muscle?

A

near central part and branch through connective tissue sheaths

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41
Q

skeletal muscle generates a large amount of what? what does this muscle need?

A

generates waste

needs nutrients/oxygen

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42
Q

what supports cells and reinforces whole muscle; connective tissue sheaths of skeletal muscle?

A

epimysium, perimysium, and endomysium

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43
Q

dense irregular connective tissue surrounding entire muscle; may blend with fascia

A

epimysium

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44
Q

fibrous connective tissue surrounding fascicles

A

perimysium

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45
Q

fine areolar connective tissue surrounding each muscle fiber

A

endomysium

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46
Q

skeletal muscle attaches in what 2 places?

A

insertion

origin

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47
Q

insertion

A

movable bone

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48
Q

origin

A

immovable (less movable bone)

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49
Q

attachments can be ______ or _______.

A

direct or indirect

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50
Q

direct

A

epimysium fused to periosteum of bine or perichondrium of cartilage

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51
Q

indirect

A

connective tissue wrappings extend beyond muscles as tendons/aponeurosis

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52
Q

fascicle

A

discrete bundle of muscle cells, segregated from rest of muscle by connective tissue sheath

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53
Q

what is muscle surrounded by? what is fascicle surrounded by?

A

muscle surrounded by epimysium

fascicle surrounded by perimysium

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54
Q

muscle fiber

A

elongated multinucleate cell; striated

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55
Q

what is muscle fiber surrounded by?

A

endomysium

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56
Q

myofibrils

A

rodlike contractile elements that occupy most of muscle cell volume

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57
Q

what are myofibrils composed of and how are they arranged?

A

sarcomeres arranged end to end

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58
Q

sarcomere

A

contractile unit composed of myofilaments made up of contractile proteins

59
Q

what are the 2 types of myofilaments?

A

thick and thin

60
Q

what do thick filaments contain?

A

bundled myosin molecules

61
Q

what do thin filaments contain?

A

actin molecules

62
Q

what produces muscle shortening?

A

sliding of thin filaments past thick

63
Q

elastic filaments

A

maintain organization of A band and provide elastic recoil when muscle contractions end

64
Q

long, cylindrical cell
multiple peripheral nuclei
what is the muscle fiber?

A

skeletal

65
Q

sarcolemma

A

plasma membrane

66
Q

sarcoplasm

A

cytoplasm

67
Q

glycosomes

A

glycogen storage

68
Q

myoglobin

A

O2 storage

69
Q

densely packed, rodlike
80% cell volume
contain sarcomeres
exhibit striations

A

myofibrils

70
Q

striations

A

perfectly aligned repeating series of dark A bands and light I bands

71
Q

H zone

A

lighter region in midsection of dark A band where filaments don’t overlap

72
Q

M line

A

line of protein myosin bisects H zone

73
Q

Z disc (line)

A

coin-shaped sheet of proteins on midline of light I band

anchors thin filaments and connects myofibrils to one another

74
Q

thick filaments

A

run entire length of A band

75
Q

thin filaments

A

run length of I band and partway into A band

76
Q

sarcomere

A

region between 2 successive Z discs

smallest contractile unit of muscle fiber

77
Q

what is composed of thick and thin myofilaments made of contractile proteins?

A

sarcomere

78
Q

what extend across I band and partway in A band and are anchored to Z discs?

A

actin myofilaments

79
Q

what extend length of A band and connected at M line?

A

myosin myofilaments

80
Q

what are composed of 2 heavy and 4 light polypeptide chains?

A

thick filament

81
Q

myosin tails contain what?

A

2 interwoven heavy polypeptide chains

82
Q

myosin heads contain what?

A

2 smaller, light polypeptide chains

83
Q

2 smaller light polypeptide chains act as ______ during contraction.

A

cross bridges

84
Q

myosin heads are binding sites for what?

A

actin of thin filaments

ATP

85
Q

ultrastructure of thin filament

A

twisted double strand of fibrous protein F actin

86
Q

F actin consists of ______ actin subunits.

A

G (globular)

87
Q

what actin bears active sites for myosin head attachment during contraction?

A

G actin

88
Q

tropomyosin and troponin

A

regulatory proteins bound to actin

89
Q

what is elastic filament composed of?

A

titin

90
Q

what holds thick filaments in place, helps recoil after stretch, and resists excessive stretching?

A

elastic filament

91
Q

dystrophin

A

links thin filaments to proteins of sarcolemma

92
Q

nebulin, myomesin, C proteins bind ___ or ___ together and maintain alignment.

A

filaments or sarcomeres

93
Q

what is a network of smooth endoplasmic reticulum surrounding each myofibril?

A

sarcoplasmic reticulum

94
Q

what is the function of sarcoplasmic reticulum?

A

regulate intracellular Ca2+ levels (stores/releases)

95
Q

what are continuations of sarcolemma called?

A

T tubules

96
Q

what is continuous with extracellular space?

A

lumen

97
Q

T tubules increase muscle fiber’s ______

A

surface area

98
Q

T tubules penetrate cell’s interior at each ______

A

A-I band junction

99
Q

T tubules associate with paired terminal cisterns to form ___(1)___ that encircle each ___(2)___

A

(1) triads

(2) sarcomere

100
Q

what conducts electric impulses deep into muscle fiber; into every sarcomere?

A

T tubules

101
Q

integral proteins protrude into inter membrane space from T tubule and SR cistern membranes to act as _____

A

voltage sensors

102
Q

SR foot proteins

A

gated channels that regulate Ca2+ release from SR cisterns

103
Q

what occurs when tension generated by cross bridges on thin filaments exceeds forces opposing shortening?

A

shortening

104
Q

in relaxed state, thin and thick filaments overlap only at ends of ______.

A

A band

105
Q

cross bridges

A

myosin heads bind to actin

106
Q

ratcheting pulls ______ toward _______

A

pulls Z disc toward M line

107
Q

first step for skeletal muscle to contract

A

activation at neuromuscular junction

must generate action potential in sarcolemma

108
Q

2nd step for skeletal muscle to contract

A

excitation-contraction coupling

action potential propagated along sarcolemma and intracellular Ca2+ levels rise

109
Q

what stimulates skeletal muscles?

A

somatic motor neurons

110
Q

axon of motor neurons travel from central nervous system via ______ to skeletal muscle.

A

nerves

111
Q

each axon ending forms ______ with a single muscle fiber.

A

neuromuscular junction

112
Q

ACh binding opens ion channels in the receptors that allow simultaneous passage of ___(1)___ into muscle fiber and ___(2)___ out of muscle fiber.

A

(1) Na+

(2) K+

113
Q

what produces a local change in the membrane potential called end plate potential?

A

when more Na+ ions enter than K+ ions exit

114
Q

how does ACh breakdown?

A

by acetylcholinesterase

115
Q

where is the neuromuscular junction situated?

A

midway along length of muscle fiber

116
Q

synaptic cleft

A

gel filled space that separates axon terminal and muscle fiber

117
Q

acetylcholine

A

neurotransmitter in synaptic vesicles of axon terminal

118
Q

what does the NMJ include?

A

axon terminals, synaptic cleft, junctional folds

119
Q

events at the neuromuscular junction

A
  1. nerve impulse arrives at axon terminal > ACh released into synaptic cleft
  2. ACh diffuse across cleft and binds with receptors on sarcolemma
  3. electrical events generate action potential
120
Q

what does breaking down ACh do?

A

prevents continued muscle fiber contraction in absence of additional stimulation

121
Q

3 steps of generating action potential

A

end plate potential
depolarization
repolarization

122
Q

local depolarization
ACh binding opens chemically (ligand) gated ion channels
simultaneous diffusion of Na+ in and K+ out

A

end plate potential

123
Q

end plate potential spreads to adjacent membrane areas
voltage gated Na+ channels open
influx of Na+ decreases membrane voltage toward threshold
AP initiated and muscle fiber contraction starts

A

depolarization

124
Q

restore electrical conditions of RMP
Na+ channels close and K+ channels open
K+ efflux restores resting polarity
resting state restored

A

depolarization

125
Q

refractory period

A

fibers cannot be stimulated until depolarization complete

126
Q

events that transmit AP along sarcolemma lead to what?

A

sliding of myofilaments

127
Q

latent period

A

time when E-C coupling events occur

time between AP initiation and beginning of contraction

128
Q

steps initiating muscle contraction (1st step)

A

nerve impulse reach axon terminal > voltage-gated calcium channels open > ACh released to synaptic cleft

129
Q

steps initiating muscle contraction (2nd step)

A

ACh bind to receptors on sarcolemma > open ligand-gated Na+ and K+ channels > end plate potential

130
Q

steps initiating muscle contraction (3rd step)

A

open voltage gated Na+ channels > AP propagation

131
Q

steps initiating muscle contraction (4th step)

A

voltage sensitive proteins in T tubules change shape > SR release Ca2+ to cytosol

132
Q

when do tropomyosin block active sites on actin, myosin heads cannot attach to actin, and muscle fibers relax?

A

when theres low intracellular Ca2+ concentration

133
Q

when do Ca2+ bind to troponin and has troponin change shape, move tropomyosin away from myosin binding sites, and has myosin heads bind to actin causing sarcomere shortening and muscle contraction?

A

when theres a higher intracellular Ca2+ concentrations

134
Q

what happens to Ca2+ when nervous stimulation ceases?

A

Ca2+ pumped back into SR and contraction ends

135
Q

cross bridge cycle continues as long as ______ and ______ are present

A

Ca2+ signal and adequate ATP present

136
Q

cross bridge formation

A

high energy myosin heads attach to thin filaments

137
Q

working (power) stroke

A

myosin head pivots and pulls thin filament toward M line

138
Q

cross bridge detachment

A

ATP attaches to myosin head and cross bridge detaches

139
Q

cocking of myosin head

A

energy from hydrolysis of ATP cocks myosin head into high energy state

140
Q

cross bridge cycle steps (1-4)

A
  1. cross bridge formation
  2. power (working) stroke
  3. cross bridge detachment
  4. cocking myosin head
141
Q

3-4 hours after death muscles begin to stiffen with weak rigidity at 12 hours post mortem

A

rigor mortis

142
Q

how do cross bridges form in rigor mortis?

A

dying cells take in calcium

143
Q

is ATP generated to break cross bridges in rigor mortis?

A

no

A&P I Lecture (8 decks)

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