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Phys 208 > Muscles--Skeletal > Flashcards

Muscles--Skeletal Flashcards

1
Q

what are the functional properties of muscle?

A

contractility, excitability, elasticity, extensibility

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2
Q

skele muscles made up of ___ that are multinucleated and have a ___ appearance

A

myofibrils; striated

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3
Q

cardiac muscle have ___ nucleus(nuclei)

A

single

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4
Q

purpose of smooth muscle?

A

mech. control of: digestive, urinary, repro tract, blood vessels, airways

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5
Q

smooth muscle is ___ shaped

A

spindle

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6
Q

skel muscles attached to bones by ___

A

tendons

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7
Q

___ is closest to trunk/more stationary bone; ___ is more mobile attachment

A

origin; insertion

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8
Q

skel. muscle is ___% body weight, ____% daily energy expenditure (not include BMR)

A

40; 15-60

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9
Q

skel muscle makes up ____% of BMR

A

20

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10
Q

bundle of muscle fibres

A

fascicle

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11
Q

cell membrane of muscle called:

A

sarcolemma

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12
Q

back bone of thin fil, db stranded alpha helical polymer, has binding site

A

actin

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13
Q

two identical alpha helicies coil around each other and sit in actin grooves, regulating myosin binding

A

tropomyosin

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14
Q

what is the troponin complex?

A

trop T, trop C, trop I (every 7 actin cules)

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15
Q

thick fil consist of ___ myosin cules, ___ intertwined heavy chains w/ globular heads

A

250; 2

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16
Q

myosin head contains :

A

region bind ATP and region for actin binding

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17
Q

_____ regulates ATPase activity

A

regulatory light chain

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18
Q

____ stabilizes myosin head

A

alkali light chain (more important in smooth muscle)

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19
Q

largest protein extending from M band to Z disk, involved w/ elastic recoil

A

titin

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20
Q

large potein wraps around thin fil, reg. lenth and stability of thin fil

A

nebulin

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21
Q

endings of sarcomeres, zigzag, attachment place for thin fil

A

Z disk

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22
Q

____ are lightest bands of sarcomere, Z disk is in centre

A

I bands

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23
Q

____ is darkest band, including entire length of thick and some overlap

A

A band

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24
Q

central region of A band only consist of thick fil

A

H zone

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25
Q

equivalent to Z disk but for thick fil

A

M line

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26
Q

path of initiation of skel muscle contract?

A

lower motor neuron–>alpha motor neuron–>ventral horn–>muscle fibres

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27
Q

what is a motor unit?

A

single motor neuron and all fibres it innervates

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28
Q

what is the neuromusc junction?

A

area where motor neuron makes synaptic contact w/ muscle fibre

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29
Q

what are brain regions involved in voluntary mvmt?

A

premotor, basal ganglia, thalamus, midbrain, cerebellum

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30
Q

upper motor neuron (brain–>spinal cord) and lower motor neuron (spinal –> muscle) referred to collectively as:

A

corticospinal tract

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31
Q

neurodegenerative motor neuron disease

A

amyotrophic lateral sclerosis

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32
Q

____% ALS genetically inherited, ___% of these due to mutation in ___

A

10; 25; SOD

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33
Q

3 coponents of neuromusc junction:

A

1) presynaptic motor neuron terminal
2) synaptic cleft
3) postsynaptic membrane of skel muscle

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34
Q

motor neuron vesicles contain ____, muscle mem contain _____

A

Ach; nicotinic ACh receptor (need two ACh to open)

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35
Q

acetylcholine is broken down by ____

A

acetylcholinesterase (in cleft)

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36
Q

what happens to broken down choline?

A

transport back to motor neuron and combined w/ Acetyl CoA by cholin acetyltrasferase–>make ACh again–>ACh-H exchanger move ACh into synaptic vesicles

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37
Q

disorder of neuromusc transmission, common in cranial muscles

A

myasthenia gravis

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38
Q

myasthenia gravis mainly ____ thru production of antibodies, but can be ____

A

autoimmune; congenital (# receptors, v size of folds, ^ synaptic cleft)

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39
Q

how to treat myasthenia gravis?

A

AChesterase inhibitors

40
Q

sarcolemma penetrate into muscle fibre in form of ___ that contain Ca storage organelles called ___

A

T tubules ; sarco reticulum

41
Q

how does Ca enter cyto?

A

voltage gated Ca channels or from sarco reticulum

42
Q

process by which electrical excitation of surface mem trigger ^ in [Ca]

A

excitation-contraction coupling

43
Q

T tubules surround myofibrils at ___ and ___ bands; tubules associated w/ 2 ___to form a “triad”

A

A; I; cisternae

44
Q

___Type channels and ___ are mechanically coupled

A

L; RyR

45
Q

Ca induced Ca release is more important in ____ muscle

A

cardiac

46
Q

release of ____ initiates power stroke

A

inorganic phosphate

47
Q

how does Ca cause contraction?

A

bind trop C–>conformation change–>trop complex and tropomyosin move to reveal myosin binding site

48
Q

what is cross bridge cycling?

A

myo attach to actin–>ATP bind to release it–>hydrolyze to ADP to cock and form cross bridge–>inorganic P release to power stroke

49
Q

during muscle contraction, ___ zone and ___ band shoten, while ____ band remains constant

A

H; I; A

50
Q

how is Ca removed to xtracell space?

A

Na-Ca-xchanger or Ca ATPase

51
Q

Ca reuptake into SR mediated by:

A

SERCA type pump

52
Q

___ in SR inhibits SERCA pumps; ___ exists to delay this inhibition

A

^ Ca; calsequestrin (triad region, 50 Ca binding sites/cule)

53
Q

how does calsequestrin work?

A

form complex with RyR, buffer Ca and unload Ca near RYR to facilitate EC coupling

54
Q

why does rigor mortis occur?

A

Ca leak into sarco, bind troponin–>stuck in latch state cuz ATP production stops (can’t release), and Ca can’t be removed

55
Q

delay between muscle fibre AP and contraction

A

latent period (Ca being released and binding troponin)

56
Q

most readily available back up to ATP is ____

A

phosphocreatine (10 seconds)

57
Q

muscle has a lot of this enzyme

A

creatine kinase

58
Q

why ATP needed in muscles?

A

sodium postassium pump, remove Ca, activate x bridge cycle

59
Q

primary mech for long term regen of ATP

A

aerobic metabolism

60
Q

___ fatigue precedes ___ fatigue

A

central (feeling); physiological

61
Q

why muscle fatigue?

A

low pH from acid production during ATP hydrolysis

62
Q

why periipheral fatigue?

A

1) ACh synth can’t keep up with neuron firing rate–>fail reach threshold,
2) probs w/ excitation contraction coupling (NaK pump can’t keep up)
3) buil up of inorganic P and ADP

63
Q

how does inorganic P/ADP cause fatigue?

A

slow down cycling, reduce Ca reuptake, prevent RyR release Ca , v sensitivity to trop C

64
Q

type one is ___fibres; two is __

A

slow; fast

65
Q

type 2a is:

A

fast-ox-glycolytic

66
Q

type 2x is:

A

fast-glyco

67
Q

tension directly proportional to ______

A

number of crossbridges formed (overlap)

68
Q

max contraction known as ____, which is subdivided into ___ and ___

A

tetanus; unfused, fused

69
Q

group of all motor neurons innervating single muscle called:

A

motor neuron pool

70
Q

during submaximal contraction, CNS mod. firing rates of motor neurons to allow diff units maintain contraction to prevent fatigue. THis is called:

A

asynchronous recruitment

71
Q

force tending to pull attachment points of muscle towards one another

A

tension

72
Q

creating force w/out moving load called ___, creating force to gen. mvmt called ___

A

isometric; isotonic

73
Q

this type of contraction is best for muscle building

A

eccentric

74
Q

how do sarco shorten during isometric w/out muscle change length?

A

elastic elements (tissues, tendons in series)–>ALWAYS start with isometric contract

75
Q

4 examples of muscle adaptation?

A

1) ^ ATP-synth capacty (increase mito, glycolytic enzymes, cap. density)
2) muscle cross section (hypertrophy)
3) muscle fibre type transition (some endurance convert fast glyco to fast ox. glyco)
4) ^ strength w/out hypertrophy (motor learning)

76
Q

where does hyperplasia occur?

A

in cats; when myosatellite cells involved in muscle repair form new myofibrils in development , split when become too large

77
Q

how does resistance training cause hypertrophy

A

satellite cells donate nuclei to injury sites (chemotaxis) –> more myosin and actin , express myogenic reg. factors that aid repair, regen and growth; overload stim cause ^ # sarcomeres in muscle length and glycogen

78
Q

why does atrophy occur?

A

immobilization, bed rest, unloading (space), food deprive cause ^ myostatin, age, cachexia, musc. dystrophy, denervation

79
Q

___ send info about stretch to CNS, found among extrafusal fibres, arranged parallel to muscle fibres

A

muscle spindles

80
Q

found in capsules and ligaments around joints, stim by mech distortion accompany changes in pos. of bones

A

joint receptors

81
Q

muscle spindles aare ___ active, lack ___ in central region, responsible for____, made up of ___ neuron wrapped around ___ fibres

A

tonically; myofibrils; normal resting muscle tone; sensory; intrafusal

82
Q

____ maintains spindle function when muscle conracts

A

alpha-gamma coactivation

83
Q

sensory neuron interwoven among collagen in tendon, only active when high amounts fo tension, originally proposed to control ___

A

golgi tendon organ; inhibitory reflexes prevent damage

84
Q

____ inhibition controls mvmt around joint

A

reciprocal

85
Q

____ reflex pull limbs away from painful stim

A

flexion

86
Q

complicated flexion reflex

A

crossed-extensor reflex

87
Q

mvmts loosely classified into these 3 categories:

A

reflex, voluntary, rhythmic

88
Q

___ is important for relaying/modifyig signals as pass from spinal cord/basal ganglia/cerebellum–>cerebral cort

A

thalamus

89
Q

what are 3 levels nervous sys control mvmt?

A

1) spinal cord (integrate spinal reflex, central pattern generators for rhythmic)
2) brainstem/cerebellum (postural reflex, hand/eye)
3) cortex+basal ganglia (voluntary)

90
Q

phases of vol. mvmt?

A

plan–>initiate–>execute

91
Q

corticospinal tract cross to opp. side at ____ located in ____

A

pyramids; medulla

92
Q

this disease reflects basal ganglia dysfunction; loss of ___ containing neurons in _____

A

Parkinson’s; dopamine; substantia nigra

93
Q

parkinson’s is characterized by:

A

bradykinesia, akinesia, rigidity, tremors, cog. dysfunction

94
Q

___ cause parkinson’s as a byproduct of synthetic heroine

A

MPTP

95
Q

how to treat parkinson’s?

A

MAO inhibitors, dopamine precursors

Phys 208 (10 decks)

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