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A&P Lecture Unit 3 > Skeletal Muscles > Flashcards

Skeletal Muscles Flashcards

1
Q

Each muscle fiber is served by one __, one __, and one or more veins.

A

artery, nerve

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2
Q

Where do all innervations enter/exit in the muscle?

A

The central part, and branch through connective tissue sheaths

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3
Q

Every skeletal muscle fiber is supplied by a __ ___ that controls its activity.

A

Nerve ending

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4
Q

Skeletal muscles have a huge nutrient and oxygen need; generates large amount of __ __

A

Metabolic waste

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5
Q

What are the connective tissue sheaths of skeletal muscle, external to internal?

A

Epimysium
Perimysium
Endomysium

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6
Q

What do the connective tissue sheaths of skeletal muscles do?

A

Support cells; reinforce whole muscle

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7
Q

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

A

Epimysium

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8
Q

Fibrous connective tissue surrounding fascicles (groups of muscle fibers)

A

Perimysium

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9
Q

Fine areolar connective tissue surrounding each muscle fiber

A

Endomysium

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10
Q

Skeletal muscle attach in at least 2 places. What is the insertion?

A

Moveable bone, farthest point

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11
Q

What is the origin?

A

Immoveable bone, closest point of attachment

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12
Q

Epimysium fused to periosteum of bone or perichondrium of cartilage

A

Direct attachment

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13
Q

Connective tissue wrappings extend beyond muscle as ropelike tendon or sheetlike aponeurosis

A

Indirect attachment

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14
Q

A muscle consists of hundreds of thousands of muscle cells, plus connective tissue wrappings, blood vessels, and nerve fibers. It is covered externally by the ___.

A

Epimysium

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15
Q

A fascicle is a discrete bundle of muscle cells, segregated from the rest of the muscle by a connective tissue sheath. The fascicle is surrounded by

A

Perimysium

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16
Q

A muscle fiber is an elongated multinucleated cell; it has a banded (striated) appearance. The muscle fiber is surrounded by

A

Endomysium

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17
Q

Myofibrils are rodlike contractile elements that occupy most of the muscle cell volume. Composed of sarcomeres arranged end to end, they appear banded, and bands of adjacent myfibrils are aligned. What are myofibrils composed of?

A

Composed of bundles of myofilaments = sarcomeres

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18
Q

A sarcomere is the __ __, composed of myofilaments made up of contractile proteins.

A

Contractile unit

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19
Q

Contractile myofilaments are of two types: __ and __.

A

Thick and thin

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20
Q

Thick filaments contain bundled ___ molecules.

A

myosin

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21
Q

The sliding of the thin filaments past the thick filaments produces muscle ___.

A

Shortening

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22
Q

Plasma membrane is called

A

Sarcolemma

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23
Q

Cytoplasm of the skeletal muscle fiber

A

Sarcoplasm

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24
Q

What is the sarcoplasm made of?

A

Glycosomes for glycogen storage

Myoglobin for O2 storage

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25
Q

What are the modified structures of skeletal muscle fibers?

A

Myofibrils, sarcoplasmic reticulum, and T tubules

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26
Q

What are myofibrils?

A
  • Densely packed, rodlike elements
  • ~80% of cell volume
  • Contain sarcomeres (contracile units)
  • Exhibit striations
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27
Q

Sarcomeres are the __ __ of myofibrils and contain ___

A

Contractile units

Myofilaments

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28
Q

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

A

Striations

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29
Q

Color of A bands?

A

Dark

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30
Q

Color of I bands?

A

Light

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31
Q

What is the connective tissue of epimysium?

A

Dense irregular connective tissue

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32
Q

What is the connective tissue of perimysium?

A

Fibrous connective tissue

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33
Q

What is the connective tissue of endomysium?

A

Fine areolar connective tissue

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34
Q

Myofibrils contain…?

A

Sarcomeres

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35
Q

Sarcomeres contain…?

A

Myofilaments

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36
Q

Lighter region in midsection of dark A band where filaments do not overlap

A

H zone

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37
Q

What does the H in H zone stand for?

A

“helle” ; bright

lighter region in midsection of A band where filaments do not overlap

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38
Q

Line of protein myomesin bisects H zone

A

M line

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39
Q

What does the M in M line stand for?

A

M for middle

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40
Q

Coin-shaped sheet of proteins on midline of light I band that anchors thin filaments and connects myofibrils to one another

A

Z disc

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41
Q

What does the Z in Z disc stand for?

A

Represents the zig zag appearance of the Z disc

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42
Q

Thick filaments …

A

Run entire length of an A band

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43
Q

Thin filaments …

A

Run length of I band and partway into A band

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44
Q

Region between two successive Z discs.

A

Sarcomere

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45
Q

What does the word sarcomere literally translate into?

A

Muscle segment

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46
Q

What is the smallest contractile unit (functional unit) of muscle fiber?

A

Sarcomere

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47
Q

Sarcomeres align along ___ like boxcars of train, extending from one Z disc to another and to another.

A

myofibril

48
Q

Sarcomeres contains A band with 1/2 ____ at each end.

A

I band

49
Q

Sarcomeres are composed of thick and thin myofilaments made of __ __.

A

Contractile proteins

50
Q

Each bright H zone is bisected vertically by a dark line called the M line formed by molecules of the protein …?

A

Myomesin

51
Q

Each light I band (where only thin filaments are) has a midline darker interruption called the

A

Z disc

52
Q

Region of a sarcomere with thick filaments only

A

H zone

53
Q

Region of a sarcomere with thin filaments only

A

I band

54
Q

Region of a sarcomere with thick filaments linked by accessory proteins

A

M line

55
Q

Thick and thin filaments overlap

A

A band

56
Q

Which filament containing myosin (red) extends the entire length of the A band?

A

Thick

57
Q

Thick filaments are connected in the middle of the sarcomere at the ___.

A

M line

58
Q

Which filament containing actin (blue), located more laterally, extends across the I band and partway into the A band?

A

Thin

59
Q

What anchors the thin filaments?

A

Z disc, the coin shaped sheet

60
Q

What filament extends from the Z disc and connects each myofibril to the next throughout the width of the muscle cell?

A

Intermediate filaments

61
Q

Myosin myofilaments are thick or thin?

A

Thick

62
Q

Actin myofilaments are thick or thin?

A

Thin

63
Q

Actin/thin myofilaments are anchored to ?

A

Z discs

64
Q

Myosin/thick myofilaments are connected at ?

A

M line

65
Q

Thick filament is composed of the protein…?

A

Myosin

66
Q

Each myosin molecule consists of __ heavy and __ light polypeptide chains

A

2, 4

67
Q

Myosin __contain 2 interwoven, heavy polypeptide chains

A

Tails

68
Q

Myosin __contain 2 smaller, light polypeptide chains that act as __ __ during contraction.

A

Heads, Cross bridges

69
Q

The globular myosin heads are the business end of myosin. Three actions of myosin heads are:

A
  • Binding sites for actin of thin filaments
  • Binding sites for ATP
  • ATPase enzymes
70
Q

Actin/thin myofilaments are composed of the protein…?

A

Actin

71
Q

Twisted double strand of fibrous protein is called

A

F actin

72
Q

F actin consists of …?

A

G actin subunits

73
Q

G actin bears __ __for myosin head attachment during contraction

A

active sites

74
Q

What are the regulatory proteins bound to actin?

A

Tropomyosin and troponin

75
Q

In the center of the sarcomere, the thick filaments lack myosin heads. Myosin heads are present only in areas of __ __ __.

A

Myosin-actin overlap

76
Q

What thin filament (which is shaped like a kidney) bears active sites for myosin head attachment during contraction?

A

G actin of thin filaments

Named for its GLOBULAR shape - “G”

77
Q

A __ filament consists of 2 strands of actin subunits twisted into a helix plus two types of regulatory proteins.

A

thin

78
Q

__ filaments bear the active sites for myosin head attachment.

A

Thin

79
Q

Each __ filament consists of many myosin molecules whose heads protrude at opposite ends of the filament.

A

thick

80
Q

Red filament:

A

Thick

81
Q

Blue filament:

A

Thin

82
Q

Where is the ATP binding site on the myosin head?

A

At the base of the myosin head

83
Q

Where are the actin-binding sites on the myosin head?

A

At the top surface of the head.

84
Q

Actin is associated with

A

Thin filaments

85
Q

Myosin is associated with

A

Thick filaments

86
Q

In the thin filaments, G actin subunits are polymerized into long actin filaments called filamentous or ___.

A

F actin

87
Q

Actin-binding site of the myosin head binds to …?

A

Active sites for myosin attachment in the G actin subunit

88
Q

Troponin and tropomyosin help control the myosin-actin interactions involved in .

A

contraction

89
Q

Which 2 regulatory proteins help form the structure of the myofibril?

A

Elastic filament

Dystrophin

90
Q

Elastic filaments maintain the organization of the A band and provide __ __when muscle contraction ends.

A

elastic recoil

91
Q

Elastic filament is composed of the protein

A

Titin

92
Q

Dystrophin links thin filaments to proteins of the

A

Sarcolemma

93
Q

Nebulin, myomesin, C proteins bind filaments or sarcomeres together; also to __ __.

A

Maintain alignment

94
Q

Skeletal muscles contain two sets of intracellular tubules that help regulate muscle contraction. What are they?

A
  • The sarcoplasmic reticulum

- T tubles

95
Q

Which of the two sets of intracellular tubules are a network of smooth endoplasmic reticulum surrounding each myofibril?

A

Sarcoplasmic reticulum

96
Q

The __ __ has interconnecting tubules that surround each myofibril the way the sleeve of a loosely crocheted sweater surrounds your arm.

A

sarcoplasmic reticulum

97
Q

Most sarcoplamic reticulum run _____. along the myofibril, communicating with each other at the __ __.

A

Longitudinally (east to west)

H zone

98
Q

Pairs of terminal cisterae form ___ __ __.

A

perpendicular cross channels

99
Q

Other sarcoplasmic reticula form larger, perpendicular cross channels at the A band-I band junctions, and always occur in pairs. These are called?

A

Terminal cisterns

100
Q

Terminal cisterns literally mean

A

End sacs

101
Q

Where do terminal cisterns form?

A

At the A band - I band junctions

102
Q

Terminal cisterns always run ____ and always form in ___.

A

Perpendicularly, pairs

103
Q

What does the SR do?

A
  • Regulates intracellular levels of calcium

- Stores and releases calcium upon muscle’s stimulation to contract

104
Q

At each A band- I band junction, the sarcolemma of the muscle cell protrudes deep into the cell interior, forming an elongated tube called the __ __.

A

T tubule

105
Q

The T tubule is a continuation of the

A

Sarcolemma

106
Q

T tubule lumen are continuous with the

A

extracellular space

107
Q

T tubules act to

A

Increase muscle fiber’s surface area

108
Q

Where do T tubules penetrate?

A

Penetrate cell’s interior at each A band–I band junction

109
Q

T tubules associate with paired terminal cisterns to form ___, which encircles each sarcomere

A

triads

110
Q

A triad, in order, looks like

A

Terminal cistern,
T tubule,
Terminal cistern

111
Q

T tubules conduct ___ deep into muscle fiber; every sarcomere.

A

impulses

112
Q

The roles of the T tubules and SR in providing signals for ___ are tightly linked.

A

contraction

113
Q

At the triads, ___ ___ (some from the T tubule and some from the SR) protrude into the intermembrane spaces.

A

integral proteins

114
Q

The protruding integral proteins of the T tubule act as ___ ___.

A

voltage sensors

115
Q

The voltage sensors of the __ form gated channels through which the teminal cisterns release Ca2+.

A

SR

116
Q

The voltage sensors of the Sr form __ ___ through which the terminal cisterns release Ca2+.

A

gated channels

117
Q

The voltage sensors of the SR form gated channels through which the __ __ release Ca2+.

A

terminal cisterns

A&P Lecture Unit 3 (5 decks)

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