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Histology exam 2 > Muscle and Contractile filaments > Flashcards

Muscle and Contractile filaments Flashcards

1
Q

skeletal muscle surrounded by dense connective tissue

A

epimysium

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2
Q

skeletal muscle consists of muscle fiber bundles (fascicles) surrounded by

A

perimysium

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3
Q

skeletal muscle fiber bundles consist of individidual

A

multinucleated muscle fibers (cells)

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4
Q

skeletal muscle cells surrounded by a basal lamina and reticular fibers

A

endomysium

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5
Q

skeletal endomysium contains

A

capillaries that supply blood to the muscle fiber

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6
Q

infrequent small cells found between the sarcolemma and basal lamina of skeletal muscle

A

satellite cells

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7
Q

satellite cells

A

stem cells that may proliferate after trauma to form new myoblasts

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8
Q

myofibrils are made up of

A

myofilaments

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9
Q

another name for a muscle fiber

A

muscle cell

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10
Q

muscle fibers have dark _ bands and light _ bands

A

A

I

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11
Q

may see a dark _ line bisecting the I band

A

Z

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12
Q

functional unit of contraction

A

sarcomere

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13
Q

T-tubule flanked on both sides by dilations of sarcoplasmic reticulum

A

triad

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14
Q

triad is located at

A

the junction of the A and I bands

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15
Q

skeletal muscle interaction site between nerve axon and muscle

A

motor end plate

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16
Q

axon loses _ near the muscle cell

A

myelin sheath

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17
Q

a nerve and the muscle it innervates

A

motor unit

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18
Q

skeletal muscle axon terminals contain _ that diffuses across _ and binds to receptors located in the _ of the sarcolemma

A

Ach
synaptic cleft
junctional folds

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19
Q

binds to presynaptic membrane and blocks Ach release

A

botulism toxin

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20
Q

autoantibodies against Ach receptors

A

myasthenia gravis

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21
Q

antibodies block Ach leading to

A

progressive muscle weakness

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22
Q

action potential from motor end-plate goes along the sarcolemma and is carried into the myofibrils by the

A

transverse T tubule system (continuous with the myofibril sacrolemma)

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23
Q

depolarization of the T tubule system causes release of calcium from

A

terminal cisternae of the sarcoplasmic reticulum

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24
Q

calcium release leads to interaction of actin and myosin leading to

A

muscle contraction

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25
Q

3 muscle fiber types

A

red, white, and intermediate

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26
Q

type I, slow twitch: high myoglobin content, numerous mitochondria with succinic dehydrogenase; fatigue resistant

A

red fibers

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27
Q

type II, fast twitch, lower myoglobin and mitochondria content than type I; have more stored glycogen; higher ATPase activity than Type I

A

white fibers

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28
Q

characteristics between type I and II

A

intermediate fibers

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29
Q

_ controls fiber type differentation

A

innervation

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30
Q

provide information of degree of muscle tension

A

stretch receptor

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31
Q

contain modified muscle fibers

A

intrafusal fibers

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32
Q

muscle spindles have

A

sensory receptors, intrafusal fibers, and neuron terminals in a fluid filled connective tissue capsule

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33
Q

intrafusal fibers may be

A

nuclear bag fibers (cluster of nuclei) or thin nuclear chain fibers

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34
Q

spindly may receive afferent sensory nerve fibers with 3 types of endings

A

annulospiral, flower spray, and y-efferents (fusimoter)

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35
Q

wind around intrafusal fibers

A

annulospiral

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36
Q

terminate in clusters

A

flower spray

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37
Q

y-efferents (fusimotor)

A

motor end plates formed near spindle poles

38
Q

after muscle injury _ transcription factor in combination with HGF induces proliferation of

A

myoD

satellite cells

39
Q

rigor mortis

A

calcium ions enter muscle cells upon death; once the ATP present is used up, the actin and myosin proteins will stay linked until decomposition

40
Q

muscle atrophy is

A

decrease in muscle fiber size; the number of muscle fibers does not change

41
Q

myofilaments have 4 main proteins

A

actin, tropomyosin, troponin, and myosin (all thin except myosin)

42
Q

attachment point for thin filaments

A

Z-disk

43
Q

thick myofilaments are only found in this band

A

A

44
Q

thin myofilaments in this band attach to Z disk and extend into A band

A

I band

45
Q

anchors actin filaments to the Z disk

A

alpha-actinin

46
Q

helps bind myofibrils to each other; linked to each other by plectin

A

desmin

47
Q

absent in Duchenne muscular dystrophy patients

A

dystrophin

48
Q

contains myosin (no heads) and creatine kinase

A

H band

49
Q

region of myomesin linking with myosin

A

M line

50
Q

A filament of _ is made of of globular actin monomers (G-actin)

A

actin (F-actin)

51
Q

actin filaments in EM

A

F-actin

52
Q

elongated protein dimer that lies in the grooves of the actin helix

A

tropomyosin

53
Q

tropomyosin binds 3 tropoinin peptides named

A

T, I, and C

54
Q

binds the Tn complex to tropomyosin

A

Tn-T

55
Q

together with tropomyosin inhibits the binding of actin to myosin

A

Tn-I

56
Q

calcium binding subunit: binding of Ca to this subunit releases the TnI-tropomyosin inhibition of actin activation of myosin ATPase

A

Tn-C

57
Q

intermediate filament that encircles Z disk of each sarcomere

A

desmin

58
Q

dystrophin

A

reinforces and stabilizes sarcolemma during contraction by linking cytoskeleton with ECM

59
Q

mutations in genes for sarcoglycans; disrupts association of sacrolemma with ECM

A

sarcoglycanopathies (limb-girdle muscular dystrophies)

60
Q

thick myofilaments of 300-400 _ molecules

A

myosin

61
Q

both a globular enzyme and a fibrous structural protein

A

myosin

62
Q

when proteolytically digested, each myosin heavy chain produces a globular head called _ and a rodlike alpha-helical tail termed _

A

heavy meromyosin

light meromyosin

63
Q

each myosin head binds

A

2 molecules of light chains

64
Q

when the membrane is depolarized and calcium released from the SR, calcium binds to the Tn-C leading to

A

exposes the myosin binding site on actin

65
Q

when myosin binds to actin and ATP hydrolysis on myosin head occurs,

A

the myosin head flexes and the actin thin filaments are pulled into the A band

66
Q

causes the release of the bond between actin and myosin

A

a new ATP molecule binding to the myosin head

67
Q

type of muscle with a single nucleus per cell more centrally located

A

cardiac muscle

68
Q

cardiac muscle fibers are composed of several cardiac muscle cells joined end to end by junctional zones called

A

intercalated disks (ID)

69
Q

ID have a transverse portion containing _ and _ and a lateral portion with _

A 
fasciae adherens and macula adherens (these bind adjacent cells together)
gap junction (this ionically couples adjacent cells)
70
Q

cardiac tissue does not regenerate, but instead it

A

forms a fibrous connective tissue scar

71
Q

cardiac muscle is usually a _ instead of a triad

A

diad

72
Q

while all calcium comes from SR for skeletal muscle, cardiac muscle gets calcium from the SR and

A

extracellular calcium

73
Q

controls active transport of calcium into SR

A

phospholamban

74
Q

amount and activity of phospholamban controlled by

A

thyroid hormone

75
Q

shape of smooth muscle

A

spindle shaped

76
Q

smooth muscle is under involuntary control of

A

sympathetic and parasympathetic nervous systems

77
Q

smooth muscle nucleus:

A

single central oval nucleus

78
Q

smooth muscle cells are surrounded by a _

A

basal lamina

79
Q

2 smooth muscle cells in contact may form

A

gap junctions

80
Q

smooth muscle plasma membrane has numerous _ on the surface and cytoplasmic _ that contain alpha actinin

A

caveolae

dense bodies

81
Q

single smooth muscle cells found around sweat, salivary, lacrimal, and mammary glands

A

myoepithelial cells of ectodermal origin

82
Q

smooth muscle located in respiratory, circulatory, digestive, and reproductive tracts

A

mesodermal origin

83
Q

smooth muscle located in the iris and ciliary body of the eye

A

ectodermal origin

84
Q

smooth muscle does not contain

A

sarcomeres

85
Q

smooth muscle is membrane associated and _ contain _, which is the functional equivalent of Z-disk

A

cytoplasmic dense bodies

alpha-actinin

86
Q

smooth muscle cytoplasm has actin and tropomyosin but no

A

troponin

87
Q

lots of _ filaments in smooth muscle that function as _

A

intermediate

links in cytoskeletal network between dense bodies

88
Q

smooth muscle has _ heavy chains and _ light chains

A

2

4

89
Q

if smooth muscle myosin is dephosphorylated it is

A

completely soluble

90
Q

for smooth muscle contraction, when stimulated, calcium increases in cytoplasm and complexes with

A

calmodulin (calcium binding protein)

91
Q

calcium-calmodulin complex activates

A

myosin light chain kinase, which phosphorylates myosin and allows it to interact with actin

92
Q

myosin light chain kinase may be activated by cAMP

A

estrogen increases cAMP while progesterone decrease cAMP

Histology exam 2 (6 decks)

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