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Histology > Muscle > Flashcards

Muscle Flashcards

(70 cards)

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1
Q

epimysium

A

dense connective tissue surrounding muscle

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2
Q

perimysium

A

C.T. surrounding muscle fiber bundles (fascicles)

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3
Q

muscle fiber

A

multinucleated muscle cell

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4
Q

endomysium

A

basal lamina and reticular fibers that cover muscle cells

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5
Q

sarcolemma

A

plasma membrane of muscles

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6
Q

satellite cells

A

rare small clefts between sarcolemma & basal lamina

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7
Q

sarcomere

A

functional unit of muscle contraction

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8
Q

triad

A

T-tubule flanked with sarcoplasmic reticulum

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9
Q

T-tubule

A

infolding of plasma membrane & is located at the A/I junction

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10
Q

motor end plate (myoneural junction)

A

interaction site between nerve axon and muscle

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11
Q

teloglia

A

schwann cells on axon near motor end plate

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12
Q

junctional folds

A

sub neural clefts of sarcolemma

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13
Q

motor unit

A

a nerve and the muscleS it innervates

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14
Q

Botulism Toxin

A

blocks Ach at presynaptic membrane

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15
Q

Curare

A

binds to Ach receptor postsynaptically

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16
Q

Myasthenia gravis

A

autoimmune disorder with autoantibodies that block Ach & leads to progressive muscle weakness

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17
Q

muscle contraction

A

action potential at motor end plate along sarcolemma and carried into myofibrils by t-tubules

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18
Q

red fibers

A

type I, slow twitch; high myoglobin content & numerous mitochondria (fatigue resistant)

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19
Q

white fibers

A

type II, fast twitch; lower myoglobin & mitochondria content, but more glycogen and higher myosin-ATPase activity

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20
Q

red fibers

A

type I, slow twitch; high myoglobin content & numerous mitochondria (fatigue resistant)

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21
Q

white fibers

A

type II, fast twitch; lower myoglobin & mitochondria content, but more glycogen and higher myosin-ATPase activity

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22
Q

intermediate fibers

A

characteristics between types I & II

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23
Q

what controls fiber type differentiation?

A

innervation

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24
Q

stretch receptor

A

spindles that sense changes in muscle length

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25
intrafusal fibers
modified muscle fibers in muscle spindles; two types called nuclear bag & nuclear stain
26
annulospiral ending
ending of muscle spindle nerve fiber with spiral configuration
27
flower spray
nerve ending of muscle spindle that terminates in clusters
28
gamma efferents (fusimotor)
motor end plates formed near spindle pores
29
muscle injury leads to?
increased expression of myoD transcription factor with hepatocyte growth factor (HGF) which causes proliferation of satellite cells
30
side-population cells
present in bone marrow & skeletal muscle and can differentiate into all major blood cell lineages
31
rigor mortis
upon death, muscle cell membranes become more permeable to calcium which promotes cross bridge attachments between myosin and actin ---> muscle fibers contract & stay linked once ATP is used up
32
muscle atrophy
disuse causes reduction in muscle fiber size not number of cells
33
myofilaments
myofibrils consist of myofilaments with four proteins actin, tropomyosin, troponin, myosin
34
A band
anisotropic band; thick filaments only (myosin)
35
I band
isotropic band; thin myofilaments attach to Z disk & extend into A band
36
Z disk
attachment point for thin filaments and contains alpha actinin
37
alpha actinin
major actin binding protein that bundles actin filaments into parallel arrays and anchors them to Z disk
38
titin
elastic protein that connects myosin to Z disk and acts like springs to keep myosin filaments centered in sarcomere
39
nebulin
inelastic protein attached to Z disk that runs parallel to actin
40
myomesin
myosin binding protein that holds myosin filaments in register at M line
41
C protein
myosin binding protein that functions similar to myomesin
42
desmin
intermediate filament that helps bind myofibrils to each other and encircles Z disk; linked with plectin
43
dystrophin
actin binding protein that's absent in duchenne MD; anchors muscle membrane proteins to actin?
44
H band
contains myosin & creatine kinase; catalyzes ATP formation from ADP & phosphocreatine
45
M line
region of myomesin linking with myosin
46
actin filament (F-actin)
made of globular actin monomers called G-actin
47
tropomyosin
elongated protein dimer that lies in grooves of actin helix and binds three troponin proteins
48
Tn-T
binds the Tn complex to tropomyosin
49
Tn-I
with tropomyosin, it inhibits the binding of actin to myosin
50
Tn-C
calcium binding subunit which releases the Tn-I tropomyosin inhibition of actin when calcium is bound
51
Intermediate filaments & Z disk
desmin encircles Z disk of each sarcomere; plectin links desmin together; alpha beta crystallin protects desmin from stress induced damage
52
Duchenne's Muscular Dystrophy
X chromosome linked mutation in dystrophin gene and leads to muscle fiber necrosis by disrupting calcium entrance into the cell
53
sarcoglycanopathies
limb girdle muscular dystrophies; mutations in genes for sarcoglycans which disrupts association of sarcolemma and ECM
54
thick myofilaments
myosin---> globular protein and fibrous structural protein
55
head of myosin
two heavy meromyosin chains that bind ATP and actin & two light chains of myosin
56
tail of myosin
rodlike alpha helical tail of light meromyosin
57
cardiac muscle
banding pattern similar to skeletal muscle but only ONE nucleus per cell; more mitochondria and extrafibullar sarcoplasm than skeletal; t-tubules larger and located at Z disk
58
cardiac muscle fiber
consists of multiple cardiac cells
59
intercalated disks
junctional zone that connects cardiac cells; contains transverse portion with fasciae adherens, macula adherens & a lateral portion with gap junctions
60
myocardial infarction causes?
cardiocytes to have an eosinophilic cytoplasm and pyknotic nuclei. 3 days ---> inflammatory cells infiltrate tissue
61
smooth muscle
involuntarily controls sympathetic or parasympathetic nervous system; spindle shaped cells with single oval shaped nucleus (1 or more nucleoli); cells surrounded with basal lamina; gap junctions for electrical current
62
smooth muscle plasma membrane contains?
caveolae on surface and cytoplasmic dense bodies with alpha actinin
63
myoepithelial cells of ectodermal origin
found around sweat, salivary, lacrimal (contract in response to Ach), and mammary glands (contract in response to oxytocin)
64
origin of smooth muscle
mesodermal origin ---> located in respiratory, circulatory, digestive, & reproductive tracts; also ectodermal ---> iris and ciliary body of eye
65
what does smooth muscle NOT contain?
sarcomeres
66
what is the functional equivalent of a Z disk in smooth muscle?
alpha actinin in cytoplasmic and membrane associated dense bodies
67
what cytoplasmic structures exist in smooth muscle?
thin: actin & tropomyosin (no troponin) intermediate: desmin & vimentin thick: myosin
68
which cytoplasmic structure serves as a link between dense bodies in smooth muscle?
intermediate filaments
69
smooth muscle myosin
structure same as striated muscle but filaments only form under certain situations; ex: if smooth muscle myosin is dephosphorylated, its completely soluble
70
smooth muscle contraction
calcium increases in cytoplasm and complexes with calmodulin; ca-calmodulin complex activates myosin light chain kinase to phos. myosin which allows actin to bind

Histology (8 decks)

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