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Histology > Muscle > Flashcards

Flashcards in Muscle Deck (70)
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1
Q

epimysium

A

dense connective tissue surrounding muscle

2
Q

perimysium

A

C.T. surrounding muscle fiber bundles (fascicles)

3
Q

muscle fiber

A

multinucleated muscle cell

4
Q

endomysium

A

basal lamina and reticular fibers that cover muscle cells

5
Q

sarcolemma

A

plasma membrane of muscles

6
Q

satellite cells

A

rare small clefts between sarcolemma & basal lamina

7
Q

sarcomere

A

functional unit of muscle contraction

8
Q

triad

A

T-tubule flanked with sarcoplasmic reticulum

9
Q

T-tubule

A

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

10
Q

motor end plate (myoneural junction)

A

interaction site between nerve axon and muscle

11
Q

teloglia

A

schwann cells on axon near motor end plate

12
Q

junctional folds

A

sub neural clefts of sarcolemma

13
Q

motor unit

A

a nerve and the muscleS it innervates

14
Q

Botulism Toxin

A

blocks Ach at presynaptic membrane

15
Q

Curare

A

binds to Ach receptor postsynaptically

16
Q

Myasthenia gravis

A

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

17
Q

muscle contraction

A

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

18
Q

red fibers

A

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

19
Q

white fibers

A

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

20
Q

red fibers

A

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

21
Q

white fibers

A

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

22
Q

intermediate fibers

A

characteristics between types I & II

23
Q

what controls fiber type differentiation?

A

innervation

24
Q

stretch receptor

A

spindles that sense changes in muscle length

25
Q

intrafusal fibers

A

modified muscle fibers in muscle spindles; two types called nuclear bag & nuclear stain

26
Q

annulospiral ending

A

ending of muscle spindle nerve fiber with spiral configuration

27
Q

flower spray

A

nerve ending of muscle spindle that terminates in clusters

28
Q

gamma efferents (fusimotor)

A

motor end plates formed near spindle pores

29
Q

muscle injury leads to?

A

increased expression of myoD transcription factor with hepatocyte growth factor (HGF) which causes proliferation of satellite cells

30
Q

side-population cells

A

present in bone marrow & skeletal muscle and can differentiate into all major blood cell lineages

31
Q

rigor mortis

A

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
Q

muscle atrophy

A

disuse causes reduction in muscle fiber size not number of cells

33
Q

myofilaments

A

myofibrils consist of myofilaments with four proteins actin, tropomyosin, troponin, myosin

34
Q

A band

A

anisotropic band; thick filaments only (myosin)

35
Q

I band

A

isotropic band; thin myofilaments attach to Z disk & extend into A band

36
Q

Z disk

A

attachment point for thin filaments and contains alpha actinin

37
Q

alpha actinin

A

major actin binding protein that bundles actin filaments into parallel arrays and anchors them to Z disk

38
Q

titin

A

elastic protein that connects myosin to Z disk and acts like springs to keep myosin filaments centered in sarcomere

39
Q

nebulin

A

inelastic protein attached to Z disk that runs parallel to actin

40
Q

myomesin

A

myosin binding protein that holds myosin filaments in register at M line

41
Q

C protein

A

myosin binding protein that functions similar to myomesin

42
Q

desmin

A

intermediate filament that helps bind myofibrils to each other and encircles Z disk; linked with plectin

43
Q

dystrophin

A

actin binding protein that’s absent in duchenne MD; anchors muscle membrane proteins to actin?

44
Q

H band

A

contains myosin & creatine kinase; catalyzes ATP formation from ADP & phosphocreatine

45
Q

M line

A

region of myomesin linking with myosin

46
Q

actin filament (F-actin)

A

made of globular actin monomers called G-actin

47
Q

tropomyosin

A

elongated protein dimer that lies in grooves of actin helix and binds three troponin proteins

48
Q

Tn-T

A

binds the Tn complex to tropomyosin

49
Q

Tn-I

A

with tropomyosin, it inhibits the binding of actin to myosin

50
Q

Tn-C

A

calcium binding subunit which releases the Tn-I tropomyosin inhibition of actin when calcium is bound

51
Q

Intermediate filaments & Z disk

A

desmin encircles Z disk of each sarcomere; plectin links desmin together; alpha beta crystallin protects desmin from stress induced damage

52
Q

Duchenne’s Muscular Dystrophy

A

X chromosome linked mutation in dystrophin gene and leads to muscle fiber necrosis by disrupting calcium entrance into the cell

53
Q

sarcoglycanopathies

A

limb girdle muscular dystrophies; mutations in genes for sarcoglycans which disrupts association of sarcolemma and ECM

54
Q

thick myofilaments

A

myosin—> globular protein and fibrous structural protein

55
Q

head of myosin

A

two heavy meromyosin chains that bind ATP and actin & two light chains of myosin

56
Q

tail of myosin

A

rodlike alpha helical tail of light meromyosin

57
Q

cardiac muscle

A

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
Q

cardiac muscle fiber

A

consists of multiple cardiac cells

59
Q

intercalated disks

A

junctional zone that connects cardiac cells; contains transverse portion with fasciae adherens, macula adherens & a lateral portion with gap junctions

60
Q

myocardial infarction causes?

A

cardiocytes to have an eosinophilic cytoplasm and pyknotic nuclei. 3 days —> inflammatory cells infiltrate tissue

61
Q

smooth muscle

A

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
Q

smooth muscle plasma membrane contains?

A

caveolae on surface and cytoplasmic dense bodies with alpha actinin

63
Q

myoepithelial cells of ectodermal origin

A

found around sweat, salivary, lacrimal (contract in response to Ach), and mammary glands (contract in response to oxytocin)

64
Q

origin of smooth muscle

A

mesodermal origin —> located in respiratory, circulatory, digestive, & reproductive tracts; also ectodermal —> iris and ciliary body of eye

65
Q

what does smooth muscle NOT contain?

A

sarcomeres

66
Q

what is the functional equivalent of a Z disk in smooth muscle?

A

alpha actinin in cytoplasmic and membrane associated dense bodies

67
Q

what cytoplasmic structures exist in smooth muscle?

A

thin: actin & tropomyosin (no troponin)
intermediate: desmin & vimentin
thick: myosin

68
Q

which cytoplasmic structure serves as a link between dense bodies in smooth muscle?

A

intermediate filaments

69
Q

smooth muscle myosin

A

structure same as striated muscle but filaments only form under certain situations; ex: if smooth muscle myosin is dephosphorylated, its completely soluble

70
Q

smooth muscle contraction

A

calcium increases in cytoplasm and complexes with calmodulin; ca-calmodulin complex activates myosin light chain kinase to phos. myosin which allows actin to bind