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Histology Exam 2 TonyFrim > Muscle > Flashcards

Muscle Flashcards

(105 cards)

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1
Q

epimysium

A

dense connective tissue that surrounds muscle

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2
Q

perimysium

A

surround muscle fiber bundles (fascicles)

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3
Q

muscle fiber bundles consist of…

A

individual multinucleate muscle fibers (cells)

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4
Q

surrounds muscle cells and contain capillaries that supply blood to muscle fiber (cell)

A

endomysium

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5
Q

what are the components of the endomysium?

A

basal lamina and reticular fibers

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6
Q

in a cross section where would you find nuclei in skeletal muscle?

A

nuclei lie in a peripheral location just beneath the sarcolemma

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7
Q

satellite cells

A

infrequent small cells found between the sarcolemma and basal lamina. Stem cells that may proliferate after trauma to form new myoblasts

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8
Q

muscle cells are the same as

A

muscle fibers

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9
Q

At the light microscope level, H and E stained muscle fibers have

A

dark A bands and light I bands.

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10
Q

functional unit of muscle contraction

A

sarcomere

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11
Q

skeletal muscle has a well developed _____ system

A

triad

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12
Q

The inner portion of skeletal muscle triad is…

A

an infolding of the plasma membrane (T-tubule)

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13
Q

The 2 side portions of skeletal muscle triad are

A

modified smooth endoplasmic reticulum (sarcoplasmic reticulum)

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14
Q

Where is the skeletal muscle T tubule system located?

A

at the junction of the A and I bands

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15
Q

interaction site between nerve axon and muscle

A

motor end plate (myoneural junction)

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16
Q

As axons get close to muscle cell, what happens to myelin sheath and Schwann cells?

A

axon loses myelin sheath near the muscle cell, but Schwann cells still cover the axon

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17
Q

interactions at the motor end plate

A

At the motor end plate the axon and Schwann cells basal lamina fuse with the muscle fiber

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18
Q

What are Schwann cells called in the region of the motor end plate?

A

teloglia

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19
Q

Axon terminals contain__________ which diffuses across synaptic cleft and binds ______________ located in the __________ ________ of the sarcolemma.

A

Axon terminals contain acetylcholine which diffuses across synaptic cleft and binds to Ach receptors located in the junctional folds of the sarcolemma.

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20
Q

Triad

A

T tubule flanked on both sides by dilations of sarcoplasmic reticule,

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21
Q

how many muscle fibers may a single axon innervate?

A

a single axon may innervate one or more muscle fibers

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22
Q

A nerve and the muscles it innervates is called a

A

motor unit

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23
Q

Myasthenia gravis

A

autoantibodies against acetylcholine receptors. Antibodies block acetylcholine which leads to progressive muscle weakness

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24
Q

Action potentials generated at the motor end plate is propagated along….

A

the sarcolemma and is carried into the myofibrils by the transverse T tubule system continuous with the myofibril sarcolemma

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25
depolarization of the T tubule system causes
the release of Ca++ from the terminal cisternae of the sarcoplasmic reticulum
26
the release of Ca++ from the terminal cisternae of the sarcoplasmic reticulum causes...
conformational changes in molecules (troponin-C) that mediate the interaction of actin and myosin and results in muscle contraction
27
Red fibers
Type I, slow twitch. High myoglobin, numeRous mitochondRia, and fatigue Resistant
28
White fibers
Type II, fast twitch. Lower myoglobin and mitochondria than Red fibers. More stored glycogen. Higher myosin-ATPase activity than Type I
29
Intermediate fibers
characteristics between Type I and II
30
What controls fiber type differentiation?
innervation. a red fiber may be changed to a white fiber by denervating and replacing with nerve from white fiber
31
Stain strongly for mitochondrial enzymes i.e succinate dehydrogenase
Red fibers (Type I)
32
Where can you find muscle spindles?
muscle spindles run parallel with the main muscle fibers
33
Spindles sense...
Spindles sense changes in muscle length (stretch receptor)
34
contents within muscle spindle
contain modified muscle fibers (intrafusal fibers) and neuron terminals in a fluid filled connective tissue capsule
35
As the sensory ending is stretched the nerve terminal discharge rate increases or decreases?
increases
36
Nerve terminal has an _____________ ending
annulospiral (wraps around fiber in spiral configuration)
37
2 types of intrafusal fibers?
nuclear bag (cluster of nuclei) and nuclear chain
38
Muscle spindles may receive afferent sensory nerve fibers with what 3 types of endings?
1)annulospiral 2)flower spray 3)γ-efferents(fusimotor)
39
annulospiral nerve ending
wind around intrafusal fibers
40
flower spray nerve ending
terminate in clusters
41
γ-efferents (fusimotor)
motor end plates formed near spindle poles
42
After muscle injury, myoD and HGF induces
proliferation of satellite cells (quiescent myoblasts)
43
Rigor mortis
Upon death, muscle cell membranes become more permeable to Ca++. The Ca ions promote the cross-bridge attachment between actin and myosin. The muscle fibers contract while acetylcholine and ATP are present or until fully contracted. Muscles use ATP to pump calcium out of the cells and once the ATP is used up, the actin and myosin proteins will stay linked until decomposition
44
muscle atrophy
atrophy due to disuse is caused by a reduction in muscle fiber size
45
Does the number of muscle fibers change with muscle atrophy?
NO.NO.NO.
46
4 main proteins found in myofilaments and associated size
actin(thin), tropomyosin(thin), troponin (thin), and myosin (thick)
47
Myofibrils are composed of
myofilaments
48
Z-disk
attachment point for thin filaments. Alpha actinin
49
Z disk bisects
I band
50
I band (isotopic band)
Thin myofilaments attach to Z disk and extend into A band
51
Elastin protein that connects myosin to Z disc
Titin
52
Inelastic protein attached to Z disc (runs parallel to actin)
Nebulin
53
Desmin
intermediate filament that helps bind myofibrils to each other. Also encircles Z-disk
54
What protein links Desmin to each other?
Plectin
55
a filament of actin (F-actin) is made of
globular actin monomers (G-actin)
56
Actin filaments are made up of __ strings of monomers wound around each other in a right handed helix
2
57
Elongated protein dimer which lies in grooves of the actin helix
tropomyosin
58
tropomyosin molecule binds these three troponin peptides
Tn-T, Tn-I, Tn-C
59
Binds the Tn complex to tropomyosin
Tn-T
60
this peptide in conjunction with tropomyosin inhibits the binding of actin to myosin
Tn-I
61
Tn-C
calcium binding subunit- binding of Ca to this subunit releases the Tn-I tropomyosin inhibition of actin activation of myosin ATPase
62
Desmin encircles the ______ of each sarcomere
Z-Disk
63
______ links desmin together
Plectin
64
Duchenne's muscular dystrophy
X linked mutation in dystrophin gene
65
Function of dystrophin
Dystrophin reinforces and stabilizes sarcolemma during contraction by linking the cytoskeleton with the ECM
66
how does a lack of dystrophin impact muscle
defective or no dystrophin disrupts sarcolemma and Ca entrance into the cell = muscle fiber necrosis
67
Sarcoglycanopathies
mutations in genes for sarcoglycans. disrupts interaction with other proteins and association of sarcolemma with ECM
68
both a globular enzyme and a fibrous structural protein
myosin
69
Basic components of a myosin molecule
2 identical heavy chains and 2 pairs of light chains
70
Each myosin head binds how many molecules of light chains
Each myosin head binds 2 molecules of light chains
71
Mechanism for muscle contraction
membrane depolarized and Ca released from the sarcoplasmic reticulum. Calcium ions then bind to the Tn-C subunit of troponin
72
Ca ions binding to the Tn-C subunit of troponin results in
spatial configuration shift of troponin and moves the tropomyosin molecule deeper into the actin helix groove and exposes the myosin binding site on actin
73
myosin binds to
actin
74
when myosin head binds to actin- energy yielding breakdown of ATP to ADP + Pi ....
flexes the myosin head and the actin thin filaments are pulled into the A band
75
Banding of cardiac muscle is similar to
skeletal muscle
76
nucleus of cardiac muscle cells
single nucleus per cell, centrally located
77
cardiac muscle fibers are composed of several cardiac muscle cells joined end to end by junctional zones called
intercalated disks
78
transverse portion of intercalated disks contain
fasciae adherens (actin filaments anchor site) and macula adherens (desmosomes) to bind adjacent cells together
79
lateral portion of intercalated disks have
gap junctions which ionically couple adjacent cells
80
cardiac muscle in relation to skeletal muscle
cardiac muscle has more mitochondria and extra fibrillar sarcoplasm than skeletal muscle. Larger T tubules in cardiac. triads are less common in cardiac muscle
81
how does cardiac muscle respond to injury
cardiac muscle responds to injury by forming a fibrous connective tissue scar.
82
how does cardiac muscle make new cells
under normal circumstances cardiac muscle does not regenerate
83
Phospholamban
controls active transport of Ca++ into sarcoplasmic reticulum lumen.
84
amount and activity of phospholamban is controlled by what hormone
thyroid hormone
85
how is smooth muscle controlled?
smooth muscle is under involuntary control of sympathetic or parasympathetic nervous system
86
appearance of smooth muscle cells
spindle shaped, but may branch. single central oval nucleus with one or more nucleoli. surround by a basal lamina
87
smooth muscle cells may secrete
collagen and elastin
88
2 smooth muscle cells may form
gap junctions and interdigitations that facilitate electrical conduction
89
Plasma membrane on smooth muscle cells has numerous _______ on the surface and cytoplasmic _______ ______ that contain alpha actinin
caveolae dense bodies
90
arranged of cells in smooth muscles can be described as
"staggered"
91
single smooth muscle cells can be found
around sweat, salivary, lacrimal, and mammary glands
92
mammary glands contract in response to
oxytocin
93
lacrimal glands contract in response to
acetylcholine
94
smooth muscle of mesodermal origin can be found in what body systems/areas
respiratory, circulatory, digestive and reproductive tracts
95
smooth muscle of ectodermal origin can be found...
in the iris and ciliary body of the eye
96
smooth muscle does not contain
sarcomeres
97
If smooth muscle is dephosphorylated
completely soluble
98
Components of smooth muscle myosin (chains)
smooth muscle has 2 heavy chains and 4 light chains like striated muscle
99
when smooth muscle is stimulated, Ca++ increases in cytoplasm and complexes with
calmodulin (Ca++ binding protein)
100
the Ca++-calmodulin complex activates
myosin light chain kinase
101
myosin light chain kinase phosphorylates myosin which causes
myosin to unfold and form filaments and this allows myosin to interact with actin
102
other than Ca-calmoduin complex what else may activate myosin light chain kinase
cAMP
103
H band contains
myosin (no heads) and creatine kinase
104
creatine kinase, which is located in the H band, catalyzes
ATP formation from ADP and phosphocreatine
105
A band
(anisotropic band)- thick myofilaments found only A band + thin myofilaments

Histology Exam 2 TonyFrim (6 decks)

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