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block 5 Anna > block 5 lecture 13 muscle physiology > Flashcards

block 5 lecture 13 muscle physiology Flashcards

1
Q

what does the muscle consist of?

A

muscle fibers, connective tissue, nerves and stem cells

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2
Q

what are the muscle stem cells?

A

satellite cells

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3
Q

when are satellite cells activated?

A

growth and muscle repair

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4
Q

what is the facsia surrounding the skeletal muscle composed of?

A

adipose tissue and connective tissue

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5
Q

what are the three layers of fascia?

A

outer epimysium
muscle fasicles surrounded by perimysium
muscle fibers are surrounded by endomysium

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6
Q

what are myofibrils surrounded by?

A

sarcolemma

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7
Q

what is the sarcolemma continuous with?

A

sarcoplasmic reticulum

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8
Q

what is the epimysium continuous with?

A

tendons

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9
Q

what is each muscle fiber made up of?

A

myofibrils

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10
Q

what are the thick filaments?

A

myosin

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11
Q

what are the thin filaments?

A

actin

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12
Q

what are the contractile proteins?

A

actin and myosin

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13
Q

what is the I band?

A

thin filaments (actin)

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14
Q

what is the A band?

A

overlap of thick and thin

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15
Q

what is the H band?

A

contains the M line - myosin filaments

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16
Q

what is the Z disc?

A

1 sarcomere

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17
Q

what causes the striation of skeletal muscle?

A

the different filaments

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18
Q

what is myosin made up of?

A

2 heavy chains and some light chains
2 heads
hinge redgion

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19
Q

what is myosin associated with?

A

actin filament

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20
Q

what is the structure of the actin filament?

A

2 molecules form together to form a double strand
it is a helical polymer
there are groovs

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21
Q

what is actin associated with?

A

tropomyosin

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22
Q

what are the elements of tropomyosin?

A

troponin C
troponin T
troponin I

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23
Q

what is the molecular mechanism of muscle contraction called?

A

sliding filament model

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24
Q

what happends when actin binds to the myosin head?

A

cross bridge forms

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25
Q

what does calcium release do to tropomyosin?

A

calcium binds to troponin C causing the molecule to undergo a conformational change

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26
Q

what does ATP do during muscle contraction?

A

causes discosiation of myosin head to actin

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27
Q

what does the myosin head act as in regard to the ATP?

A

ATP ase - hydrolyses ATP into adenosphene diphosphate and inorganic phosphate

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28
Q

what happens to the hydrolyses ATP

A

it stays bound

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29
Q

what happens when myosin head is bound to new actin molecule down the chain?

A

inorganic phosphate is released

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30
Q

what causes the power stroke?

A

inorganic phosphate is release

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31
Q

what happens to the ADP after the power stroke?

A

ADP is released and a new molecule of ATP comes along

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32
Q

why do you get rigor mortis after death?

A

there is no ATP

33
Q

what are the receptors at the neuromuscular junction for acetylecholine?

A

nicotinic cholinergic receptors

34
Q

how is the neuromuscular junction specialised?

A

highly folded

35
Q

what happens when the motor neuron is depolarised?

A

voltage gated calcium ion channels are opened

36
Q

what happens after voltage gated calcium ion channels are opened?

A

there is an influx of calcium and the calcium binds to calmodulin

37
Q

what are on the presynaptic membrane for the vsicles containing acetylecholine?

A

docking receptors - snap and snare proteins

38
Q

what happens when the vesicles containing acetylcholine fuse with the presynaptic membrane?

A

exocytosis and the neurotransmitters diffuse across the cleft

39
Q

what happens after the neurotransmitters diffuse across the cleft?

A

acetylcholine binds to nicotinic cholinergic receptors

40
Q

what happens when acetylcholine binds to nicotinic cholinergic receptors?

A

sodium and potassium channels are opened

41
Q

what happens when the sodium channels are opened on the post synaptic membrane?

A

the membrane is depolarised creating an end plate potential

42
Q

what breaks down acetylcholine?

A

acetylecholine esterase

43
Q

what does acetylecholine esterase break acetylecholine into?

A

acetate and choline

44
Q

what happens to the choline produces by the action of acetylcholine?

A

taken back to the nerve terminal for reuse

45
Q

what happens to the acetate produces by the action of acetylcholine?

A

enters the krebs cycle

46
Q

what is succinylcholine? and when is it used?

A

muscle relaxant, used in surgery, block nicotinic cholinergic receptors

47
Q

what does botulinum do?

A

inhibits the snap and snare proteins inhibiting vesicle release

48
Q

what does peridostigmine do?

A

inhibits acetylcholine esterase

49
Q

what do snakes release?

A

alphabungero toxin, binds avidly to nicotinic cholinergic receptors

50
Q

what is the potential of skeletal muscle at rest?

A

-90mv

51
Q

what is the threshold of skeletal muscle?

A

-50mv

52
Q

what is the end plate potential?

A

-15mv

53
Q

what are either side of the of the T tubules?

A

terminal cisternae

54
Q

what do the T tubule and the terminal cisternae form?

A

triad

55
Q

what does the sarcoplasmic reticulum store that is needed for moving troponin?

A

calcium ions

56
Q

what receptors are found in the T tubules?

A

dihydropyrodine receptors

57
Q

what are dihydropyrodine receptors?

A

L type calcium channels, they are voltage sensors

58
Q

what are voltage sensory connected to?

A

ryanodine receptors

59
Q

what does muscle membrane depolarisation cause?

A

opens L type calcium channels

60
Q

what causes the release of calcium in muscle cells?

A

L type calcium channels are coupled with calcium release channels

61
Q

what happens during relaxation?

A

Na/Ca exchanges the ions

calcium ions are bound in the sarcoplasmic reticulum by calrecticulin and calsequestrin

62
Q

what happens in rigor mortis?

A

calcium ions diffuse out of the sarcoplasmic reticulum allowing the myosin heads to bind to actin, there is no ATP synthesis so cross bridges cant detatch

63
Q

what are the three phases of muscle twitch

A
  1. lag phase
  2. contraction phase
  3. relaxation phase
64
Q

what is a motor unit?

A

motor nerve and the fibers it innervates

65
Q

what is the innervation ratio

A

number of muscle fibers innervated by a motor nerve

66
Q

what are the types of contraction?

A

isometric and isotonic

67
Q

what happens in isometric contraction?

A

no change in length - tendons take up stretch

68
Q

what happens in isotonic contraction?

A

muscle shortens

69
Q

what are the three muscle types involved in twitch?

A

type 1 - slow twitch
type 2a - fast glycolytic twitch
type 2b - fast twitch fatigue resistant

70
Q

what are the features of the type 1 slow twitch?

A

always oxidative, resistant to fatigue, maintain posture, good blood supply, most myoglobin, red

71
Q

what are the features of the type 2a fast twitch?

A

white fibers, poor blood supply, sucseptible to fatigue

72
Q

what are the features of the type 2b fast twitch?

A

oxidative, intermediate myoglobin, intermediate fibers, fatigue resistant

73
Q

what are the three sources of ATP

A

creatine phosphate
anaerobic respiration
aerobic respiration

74
Q

what is myopathy?

A

any muscle diseae

75
Q

what is myositis?

A

inflammatory problem

76
Q

what is muscular dystropy?

A

inherited, progressive

77
Q

what is myotonia?

A

failure of relaxation

78
Q

what is myasthenia

A

weakness on excersize

79
Q

what is channelopathies?

A

abnormal Na/K/Cl channels

block 5 Anna (16 decks)

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