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Histo & Neuro Part 2 > HISTO: Muscle, NMJ > Flashcards

HISTO: Muscle, NMJ Flashcards

1
Q

what are the types of muscle

A

skeletal, cardial, smooth

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2
Q

voluntary stiated muscle

A

skeletal

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3
Q

involuntary striated muscle

A

cardiac

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4
Q

involuntary nonstriated muscle

A

smooth

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5
Q

histological characteristic of skeletal muscle

A

striated, 30-50 nm, peripheral multiple nuclei. syncytium

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6
Q

skeletal muscle connective tissues

A

epimysium, perimysium, endomysium

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7
Q

the repeating structural unit of skeletal muscle that gives the striated appearance

A

sarcomere

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8
Q

what does the sarcomere consist of

A

z bands
i bands
a bands
m bands
h bands

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9
Q

myosin containing thick filaments

A

a bands

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10
Q

actin containing thin filaments

A

i bands

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11
Q

a-actinin crosslinking thin filaments

A

z bands

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12
Q

what is myosin composed of

A

rod and two heads

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13
Q

m- bands contain

A

myomisium, m protein and obscurin

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14
Q

main accessory protein of the skeletal and cardiac thick filaments

A

Myosin Binding Protein C (MyBP-C)

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15
Q

myosin characteristic

A

bipolar structure - has bare zone

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16
Q

what part os the thick filament interacts with actin

A

the myosin heads

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17
Q

able to bind at its amino terminal to either the myosin head or the adjacent actin thin filament

A

MyBP-C

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18
Q

thin filament characteristic

A

double helical actin arrangement + Ca2 regulatory proteins - tropomyosin and troponin

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19
Q

Ca2+ regulatory proteins

A

tropomysoin and troponin

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20
Q

troponin subunits

A

TnT - tropomysoin binding
TnC - calcium binding
TnI - inhibitory

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21
Q

extra proteins in sarcomere

A

titin - allows elasticity
tropomodulin - stabilize
nebulin
dystrohpin
desmin

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22
Q

associated with mutations affecting the expression of the dystrophin protein

A

Muscular dystrophies: DMD and BMD

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23
Q

associated with mutations on the short arm of the X chromosome for the 4 different sarcoglycan membrane proteins

A

Limb girdle LGMD

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24
Q

caused by a mutation in the gene encoding the alpha-2 chain of muscular laminin

A

Congenital msucular dystrophy

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25
Q

due to a dominate mutation in desmin

A

desmin-related myopathy

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26
Q

what occurs in desmin myopathys

A

The desmin molecules form aggregates rather than the desmin intermediate filaments. This results in disorganized myofilaments, myofibrils, and disorganized skeletal muscles

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27
Q

tubular invaginations of sarcolemma into cytoplasm at the AI junction of the sarcomere

A

t-tubules

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28
Q

sarcoplasmic reticulum function

A

specialized smooth endoplasmic reticulum able to store, release, and sequester calcium

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29
Q

what are triads

A

specialized regions in which a central t-tubule is flanked by two terminal cisterna sacs of the SR

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30
Q

what does the Terminal cisterna of SR contain

A

calsequestrin

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31
Q

what is SERCA short for

A

Smooth Endoplasmic Reticulum Calcium ATPase (SERCA)

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32
Q

SERCA function

A

pumps calcium from the cytoplasm back into sarcoplasmic reticulum and back to the terminal cisterna

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33
Q

what happens when sufficient calcium is removed from the cytoplasm

A

the contraction of the skeletal muscle will stop until the next cycle of depolarization of the sarcolemma occurs

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34
Q

Regulation of contraction is controlled by the _____ concentration in the cytoplasm

A

calcium

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35
Q

calcium regulation of contraction involves:

A

excitation contraction coupling
steric blocking mechanism of calcium regulation, sliding filament mechanism of contraction

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36
Q

which mechanism couples the nerve stimulation at the muscle cell surface to the release of calcium into the cytoplasm

A

Excitation Contraction Coupling Mechanism

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37
Q

which mechanism initiates contraction upon release of high levels of calcium

A

steric blocking

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38
Q

which mechanism is in which thick and thin filaments slide past each other to produce shortening of the sarcomere

A

sliding filament

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39
Q

excitation contraction couplings involves

A

DHSRs - depolarization sensitive channels activated when plasma mebrane depolarizes

40
Q

conformation changes of DSHRs affect

A

gated Ca2 release channels RyR1- Ca binds to actin - initiating contraction!!

41
Q

In the absence of calcium the______complex blocks the binding site for myosin on actin

A

troponin-tropomyosin

42
Q

result of sliding filaments

A

shortening of sarcomere

43
Q

stage 1 of myosin contractile cycle

A

myosin bound to thin filament, no atp

44
Q

stage 2 of myosin contractile cycle

A

atp binds to myosin causing head to detach from thin filament

45
Q

stage 3 of myosin contractile cycle

A

atp on head is hydrolyzed to adp +pi - provides energy for shape of myosin head

46
Q

stage 4 of myosin contractile cycle

A

reattachment of head to new actin - weak bindingq

47
Q

stage 5,6 of myosin contractile cycle

A

pi is released. strong binding producing power stroke that moves thin filament inwards to bare zone - adp release and cycle repeats

48
Q

relaxation conditions

A

atp present but no Ca2+

49
Q

contraction conditions

A

both atp and Ca2+ present

50
Q

rigor conditions

A

no atp present - rigor mortis

51
Q

fiber types in skeletal muscle

A

fast white glyocolytic
fast oxidative gycolitic
slow oxidative

52
Q

Type IIb (Fast White Fibers)
- largest in size; stain for fast myosin isozyme and can contract rapidly
- are easily fatigued

A

fast glycolitic fibers

53
Q

Type IIa (Intermediate fibers)
–Intermediate in
diameter; stain for fast myosin isozyme and also allow fast contraction
- less easily fatigued than white fibers

A

fast oxidative glycolitic fibers

54
Q

Type I (Slow Red
Fibers) –Smallest in diameter; stain for slow myosin isozyme and contract more slowly
- least fatiguable of fibers
- have the greatest number of mitochondria

A

slow oxidative fibers - dark stain

55
Q

skeletal muscle fiber types are stained for

A

mitochondria
dark - slow
light - fast

56
Q

is associated with a loss in skeletal muscle mass, muscle strength and force, and power

A

sarcopenia

57
Q

major loss fiber in sarcopenia

A

type II with satellite cells

58
Q

Site of innervation of skeletal muscle fibers by motor neurons

A

NMJ

59
Q

Free nerve endings lie in depressions on skeletal muscle surface known as

A

motor end plates

60
Q

The skeletal muscle cell surface is highly folded to form

A

junctional folds

61
Q

ach in synaptic vesicles bind to ___ at NMJ

A

nicotinic acetylcholine receptor (ach receptor) in sarcolemma

62
Q

ach is broken down by ___ in basal lamina

A

cholinesterase

63
Q

condition where auto-immune antibodies block, alter or destroy the acetylcholine receptors thus blocking stimulation of the skeletal muscle

A

Myasthenia gravis

64
Q

Associated with small cell carcinoma of the lung involves antibodies against many of the presynaptic membrane proteins

A

lambert eaton myasthenic syndrome

65
Q

toxins at nmj

A

botulinum, tetanus, snake

66
Q

Due to a progressive death of neurons in the spinal cord and brain that innervate the voluntary muscles. No cure.

A

Amyotrophic Lateral Sclerosis (ALS)

67
Q

characteristic of Myasthenia gravis

A

ptosis eyes, double vision, weakness, impaired swallowing, chewing, speaking

68
Q

what does botulimun toxin affect

A

Acidification of the endocytosed vesicle results in the translocation of the toxin into the cytoplasm where it cleaves synaptobrevin (VAMP)

69
Q

what does tetanus toxin affect

A

transported to the spinal cord where it translocates to the pre- synaptic terminal of inhibitory neurons

70
Q

act as sensory detectors of stretch in the skeletal muscles

A

intrafusal fibers of muscle spindle

71
Q

what sensory nerve wraps intrafusal fiber

A

type 1a

72
Q

what sensory nerve monitors stetch in tendon

A

type 1b

73
Q

cardiac muscle histological characteristics

A

striated
intermediate diameter fiber
single nuclei conterally
intercalated discs!
large mitochondria
gap junctions

74
Q

intercalated disks are part of which muscle type

A

cardiac muscle

75
Q

intercellular junctions at cardiac muscle: 3

A

fascia adherens, desmosomes, gap junctions

76
Q

in what type of muscle is mitochondria large

A

cardiac muscle - energy requirement

77
Q

where are Diads found

A

ventricular fiber of cardiac muscle

78
Q

diads composition

A

Ca2+ channels in T-tubule and 2 Ca channels in 1 flattened sac of SR terminal cisterna

79
Q

true or false:T-tubules are typically found in atrial muscle

A

false

80
Q

the main sites of calcium release for contraction in the ventricle of cardiac muscle

A

diads

81
Q

cardiac muscle Ca2+ additional release sites

A

-junctional contacts
-corbular sarcoplasmic reticulum

82
Q

SERCA2a isoform function

A

present in cardiac muscle and acts to pump calcium back into the SR between contractions

83
Q

depending on its phosphorylation state can either inhibit or open the SERCA pump channels

A

phospholamban

84
Q

what fibers bring impulse (depolarization) for contraction into ventricle

A

purkinje fibers

85
Q

excitation contraction coupling in atria is by

A

calcium release and ryanodine 2 receptor calcium channels in saccules of corbular SR

86
Q

smooth muscle histologic characteristics

A

nonstriated
spindle shaped
small fibers
single central nuclei
gap junctions electrically
Membrane attachment plaques & cytoplasmic dense bodies

87
Q

Membrane attachment plaques & cytoplasmic dense bodies containing

A

alpha actinin

88
Q

thick and thin filament structure in smooth muscle:

A

side polar structure

89
Q

which tubules are absent in smooth muscle

A

t-tubules because small diameter of cells

90
Q

Regulation of contraction in smooth muscle involves

A

Ca2 binding - calmodulin to mysoin and phosphorylation of myosin

not tropomyosin-troponin complex

91
Q

factors that can cause contraction or relaxation of smooth muscle

A

mechanical stimuli - stretching
electrical depolarization - neu
binding of hormoones

92
Q

Growth of skeletal muscle is primarily by

A

hypertrophy

93
Q

Some regeneration or repair can take place in muscles by:

A

satellite cells

94
Q

which muscle can divide and regenerate

A

smooth muscle hypertrophy in myometrium in pegnancy

95
Q

can cardiac muscle renegerate

A

can not - limited

Histo & Neuro Part 2 (13 decks)

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