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Medicine Term One > Muscles > Flashcards

Muscles Flashcards

1
Q

what do muscles do

A

generate force and movement

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2
Q

Name the three types of muscle

A

smooth, skeletal and cardiac

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3
Q

what muscle is striated

A

skeletal and cardiac

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4
Q

smooth muscle is not a striated but arrangement is

A

single unit cells, in a much more random arrangement

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5
Q

What muscle can divide and repair itself

A

smooth

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6
Q

Striated muscle is arranged in

A

Highly organised geometrical fashion of triangular and hexagons

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7
Q

striated muscle is highly packed so

A

squeezes out nucleus

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8
Q

cardiac muscle cells have what

A

intercalating disc

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9
Q

what does an intercalating disc do

A

allows electrical conductivity

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10
Q

Hard to depolarise heart due to

A

Multi connected heart providing alternative pathway due to the intercalating discs

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11
Q

What are striated muscle

A

arranged large protein filaments

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12
Q

what are muscles incased in

A

connective tissue sheaths

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13
Q

what are myoblasts

A

precursors for muscle

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14
Q

true or false myoblasts replace cells if damaged

A

false

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15
Q

what are damaged muscles replaced with

A

scar tissue

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16
Q

what happens if neighbouring cells die around muscle

A

makes it harder to contract

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17
Q

What are muscles attached to

A

Bones by tendons

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18
Q

what differentiates to form new muscle fibres when its damaged

A

satellite cells

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19
Q

Muscle cells never completely recover due to

A

limited stock of satellite cells

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20
Q

what do satellite cells move directly to

A

injury

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21
Q

What supplies muscles with oxygen for contractions

A

very deeply penetrating blood vessels

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22
Q

To much compression on blood vessels restricts muscles

A

oxygen levels, as can cut of supply

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23
Q

repeating units in striations are

A

sacromere

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24
Q

what lies between repeating units of sacromeres

A

Z line border

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25
Q

Do myosin fibres or actin fibres change in length

A

No

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26
Q

What causes contractions

A

Filaments slidding over each other and distance between them decreases

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27
Q

Thin filament and thick filament is

A

actin and myosin

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28
Q

What is the arrangement of actin

A

looks like a double helix

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29
Q

what is attached to actin

A

titin filament

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30
Q

cross head bridge is attached to what

A

Myosin filament

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31
Q

What generates the greatest force in muscle contraction

A

crosshead bridge moving actin

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32
Q

where does myosin cross head bridge head bind and latch on to

A

the binding site space on the double helix actin

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33
Q

what does the cross bridge head require to flip and detach itself from actin

A

ATP

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34
Q

Hydrolysis of ATP does what to cross bridge head

A

energises cross bridge attaching itself to actin

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35
Q

accumulation of ADP can cause what in contraction

A

muscle fatigue

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36
Q

what triggers contractions

A

fired AP causing an increase concentration of calcium ions

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37
Q

what does muscle do when relaxing

A

rid itself of calcium ions

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38
Q

what partially covers myosin binding site

A

Tropomyosin

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39
Q

Tropomyosin held in position by

A

troponin

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40
Q

Tropomyosin and troponin are an example of

A

cooperative bonding

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41
Q

What happens when calcium binds to troponin

A

pulls away Tropomyosin opening biding site for cross bridge head on myosin

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42
Q

Where is calcium ions stored

A

sacroplasm reticulum

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43
Q

what do transverse tubules deeply invaginated in the sarcolemma allow

A

depolarisation, conducting signal to release calcium ions

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44
Q

Depolarisation across cell membrane triggers

A

DHP to open calcium channel on sarcoplasmic reticulum

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45
Q

Why is relaxation powered

A

as ATP needed to remove calcium ions back into sarcoplasmic reticulum

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46
Q

How is paralysis prevented

A

muscle fibres within a motor unit may be scattered throughout muscle therefore hard to loose muscle activation

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47
Q

What is a motor unit

A

motor neurons and muscle fibres

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48
Q

Define Tension

A

force exerted by muscle

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49
Q

Load

A

force exerted on muscle

50
Q

isometric

A

generates contraction without shortening muscle fibres

51
Q

isotonic

A

shortens lengths of muscle fibres but tone of contraction kept consistent

52
Q

lengthening

A

contractions with increasing lengths

53
Q

Latent period

A

the time before excitation contraction starts

54
Q

Contraction time

A

start of tension and time when we have peak tension

55
Q

what is contraction time dependent on

A

calcium ion concentration

56
Q

what has shorter latent period, but longer contraction event

A

Isometric contractions

57
Q

what happens as load increases

A

contraction velocity and distance shortened decreases

58
Q

What is a twitch

A

contraction of muscle fibre due to single AP being fired

59
Q

Tetanus/ tetanic contraction

A

sustained level of contraction lev in any muscle fibre

60
Q

what is an unfused tetanus?

A

stimulus not frequent enough, so cell can repolarise and depolarise again

61
Q

If action potential is fired rapidly in the muscle what is it called

A

fused tension

62
Q

why is a tetanic contraction better than a twitch tension

A

Calcium ions never get low for troponin to roebuck myosin biding sites

63
Q

Less overlap over filaments means what about tension

A

there is less

64
Q

Why cant we sustain titanic contraction for long

A

high calcium contraction for to long can cause cellular degradation

65
Q

What happens if you overstretch muscle

A

Filaments interfere with each other to much and muscle does not contract

66
Q

Optimal length for isometric tension is when?

A

The maximum interaction of myosin heads to maximum number of actin binding

67
Q

Movement of limbs requires what?

A

two antagonistic groups

68
Q

define antagonistic muscle

A

muscle that opposes the action of another

69
Q

What are muscle arranged in

A

Lever system

70
Q

What does lever arrangement allow

A

Less muscular effort to be given to move a heavier load

71
Q

What allows increased maneuverability

A

Lever system

72
Q

What does ATP power for contraction

A

Ca2+ to be pumped back into sacroplasm reticulum

Binding to myosin hydrolysing Xbridge

73
Q

What is fatigue due to

A

repeated muscle contraction

74
Q

What is fatigue dependant on

A

fibre type,
length of contraction,
fitness of individual

75
Q

When does rigor occur in muscles

A

when muscle uses up vast amount of ATP

76
Q

what causes muscle fatigue during high intensity, short duration exercise

A

Increased lactic acid from glycolysis
increased ADP inhibiting xbridge
Conduction failure K doesn’t depolarise

77
Q

what causes muscle fatigue during long-term, low intensity exercise

A

decreased muscle glycogen
decreased blood glucose
dehydration

78
Q

What happens in central command fatigue

A

cerebral cortex cannot excite motor neurons, rest period

79
Q

What are the two ATP forming pathways of skeletal muscle fibres

A

oxidative or glycotic

80
Q

Skeletal muscle fibres are fast if myosin has

A

high ATPase activity, so xbridge can be energised quickly

81
Q

what do oxidative fibres contain that glycolytic don’t have

A

myoglobin

red

82
Q

Why are glycolytic fibres white

A

dont contain myoglobin pigment

83
Q

What increases oxygen delivery in oxidative fibres

A

Increased mitochondria
increased vascularisation
low diameters
contain myoglobin

84
Q

what fibres is coloured red

A

oxidative

85
Q

What diameters do glycolytic fibres have

A

large

86
Q

What do glycolytic fibres have an increase of compared to oxidative

A

glycogen

87
Q

What size of neutrons are easiest to exit first and example

A

small therefore slow oxidative fibres activated first

88
Q

What do slow oxidative resist more of compared to fast glycolytic

A

fatigue

89
Q

Fast glycolytic fibres are the largest and produce the most force due to

A

containing the most myofibrils

90
Q

What fibres are last to be activated

A

Fast glycolytic fibres

91
Q

increasing load results in increasing

A

number of active motor units

92
Q

when the number of active motor units is increasing its called

A

recruitment

93
Q

Neural control of muscle tension depends on

A

Frequency of AP’s

Recruitment of motor units

94
Q

What do muscles need to be able to survive

A

base line level of stimulation

95
Q

what is denervation atrophy and what can be the cause

A

Muscle wastage due to destroyed nerve or NMJ

96
Q

when muscle is not used what happens

A

Disuse atrophy

97
Q

What is an increase in muscle mass called

A

Hypertrophy

98
Q

How does exercise cause hypertrophy?

A

Proteins are taking up to repair muscle damage

99
Q

What is smooth muscle innervated by

A

autonomic NS

100
Q

Where does smooth muscle exist

A

in hollow organs

eg. GI tract, uterus, airways, ducts

101
Q

Structure of smooth muscle

A

spindled shape

mononucleate

102
Q

What muscle can divide through life

A

smooth muscle

103
Q

How are filaments arranged in smooth muscle

A

diagonally across the cells anchored by dense bodies to cell membrane and cell structures

104
Q

In smooth muscle what does calcium bind to during x bridge activation

A

calmodulin

105
Q

What activates myosin light chain kinase

A

calcium calmodulin complex

106
Q

What does activated myosin light chain kinase do in smooth muscle

A

phosphorylates myosin x bridge with ATP

107
Q

How does smooth muscle relax

A

dephosphorylation of X-bridges

108
Q

How can persistent stimulation s useful in blood vessels and can be maintained by

A

decreasing rate of ATP splitting
slow x bridge
Xbridge dephophorylated when still bound to actin

109
Q

What muscle are only some sites activated by Ca2+

A

smooth muscle

110
Q

In skeletal muscle ca2+ from one action potential saturates how many troponin sites

A

all

111
Q

What muscle has the greatest range and control

A

smooth muscle

112
Q

Depending on how many AP reach the cell is how smooth muscle does what

A

grade the contraction

113
Q

What does it mean than smooth muscle has a tone

A

basically has a base level of Ca2+ causing constant level of tension

114
Q

What factors affect the activity of contraction

A 
Autonomic NT 
Hormones 
local factors 
stretching of muscles 
Spontaneous electrical activity in muscle membranes ie pacemakers
115
Q

What are the two types of smooth muscle

A

single unit or multi unit

116
Q

Many cells linked by gap junctions is what kind of smooth muscle type

A

single unit

117
Q

What muscle type responds to stretch

A

single unit

118
Q

How do signal travel in single unit and how do cells contract

A

signals travel between cells

contract synchronously

119
Q

Smooth muscle sing unit fibres may contain what

A

pacemakers

120
Q

examples of multiunit fibres

A

hair, airways, large arteries

121
Q

Small blood vessels, GI tract and uterus are what smooth muscle fibres

A

single unit

Medicine Term One (59 decks)

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