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Medicine Term One > Muscles > Flashcards

Flashcards in Muscles Deck (121):
1

what do muscles do

generate force and movement

2

Name the three types of muscle

smooth, skeletal and cardiac

3

what muscle is striated

skeletal and cardiac

4

smooth muscle is not a striated but arrangement is

single unit cells, in a much more random arrangement

5

What muscle can divide and repair itself

smooth

6

Striated muscle is arranged in

Highly organised geometrical fashion of triangular and hexagons

7

striated muscle is highly packed so

squeezes out nucleus

8

cardiac muscle cells have what

intercalating disc

9

what does an intercalating disc do

allows electrical conductivity

10

Hard to depolarise heart due to

Multi connected heart providing alternative pathway due to the intercalating discs

11

What are striated muscle

arranged large protein filaments

12

what are muscles incased in

connective tissue sheaths

13

what are myoblasts

precursors for muscle

14

true or false myoblasts replace cells if damaged

false

15

what are damaged muscles replaced with

scar tissue

16

what happens if neighbouring cells die around muscle

makes it harder to contract

17

What are muscles attached to

Bones by tendons

18

what differentiates to form new muscle fibres when its damaged

satellite cells

19

Muscle cells never completely recover due to

limited stock of satellite cells

20

what do satellite cells move directly to

injury

21

What supplies muscles with oxygen for contractions

very deeply penetrating blood vessels

22

To much compression on blood vessels restricts muscles

oxygen levels, as can cut of supply

23

repeating units in striations are

sacromere

24

what lies between repeating units of sacromeres

Z line border

25

Do myosin fibres or actin fibres change in length

No

26

What causes contractions

Filaments slidding over each other and distance between them decreases

27

Thin filament and thick filament is

actin and myosin

28

What is the arrangement of actin

looks like a double helix

29

what is attached to actin

titin filament

30

cross head bridge is attached to what

Myosin filament

31

What generates the greatest force in muscle contraction

crosshead bridge moving actin

32

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

the binding site space on the double helix actin

33

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

ATP

34

Hydrolysis of ATP does what to cross bridge head

energises cross bridge attaching itself to actin

35

accumulation of ADP can cause what in contraction

muscle fatigue

36

what triggers contractions

fired AP causing an increase concentration of calcium ions

37

what does muscle do when relaxing

rid itself of calcium ions

38

what partially covers myosin binding site

Tropomyosin

39

Tropomyosin held in position by

troponin

40

Tropomyosin and troponin are an example of

cooperative bonding

41

What happens when calcium binds to troponin

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

42

Where is calcium ions stored

sacroplasm reticulum

43

what do transverse tubules deeply invaginated in the sarcolemma allow

depolarisation, conducting signal to release calcium ions

44

Depolarisation across cell membrane triggers

DHP to open calcium channel on sarcoplasmic reticulum

45

Why is relaxation powered

as ATP needed to remove calcium ions back into sarcoplasmic reticulum

46

How is paralysis prevented

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

47

What is a motor unit

motor neurons and muscle fibres

48

Define Tension

force exerted by muscle

49

Load

force exerted on muscle

50

isometric

generates contraction without shortening muscle fibres

51

isotonic

shortens lengths of muscle fibres but tone of contraction kept consistent

52

lengthening

contractions with increasing lengths

53

Latent period

the time before excitation contraction starts

54

Contraction time

start of tension and time when we have peak tension

55

what is contraction time dependent on

calcium ion concentration

56

what has shorter latent period, but longer contraction event

Isometric contractions

57

what happens as load increases

contraction velocity and distance shortened decreases

58

What is a twitch

contraction of muscle fibre due to single AP being fired

59

Tetanus/ tetanic contraction

sustained level of contraction lev in any muscle fibre

60

what is an unfused tetanus?

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

61

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

fused tension

62

why is a tetanic contraction better than a twitch tension

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

63

Less overlap over filaments means what about tension

there is less

64

Why cant we sustain titanic contraction for long

high calcium contraction for to long can cause cellular degradation

65

What happens if you overstretch muscle

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

66

Optimal length for isometric tension is when?

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

67

Movement of limbs requires what?

two antagonistic groups

68

define antagonistic muscle

muscle that opposes the action of another

69

What are muscle arranged in

Lever system

70

What does lever arrangement allow

Less muscular effort to be given to move a heavier load

71

What allows increased maneuverability

Lever system

72

What does ATP power for contraction

Ca2+ to be pumped back into sacroplasm reticulum
Binding to myosin hydrolysing Xbridge

73

What is fatigue due to

repeated muscle contraction

74

What is fatigue dependant on

fibre type,
length of contraction,
fitness of individual

75

When does rigor occur in muscles

when muscle uses up vast amount of ATP

76

what causes muscle fatigue during high intensity, short duration exercise

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

77

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

decreased muscle glycogen
decreased blood glucose
dehydration

78

What happens in central command fatigue

cerebral cortex cannot excite motor neurons, rest period

79

What are the two ATP forming pathways of skeletal muscle fibres

oxidative or glycotic

80

Skeletal muscle fibres are fast if myosin has

high ATPase activity, so xbridge can be energised quickly

81

what do oxidative fibres contain that glycolytic don't have

myoglobin
red

82

Why are glycolytic fibres white

dont contain myoglobin pigment

83

What increases oxygen delivery in oxidative fibres

Increased mitochondria
increased vascularisation
low diameters
contain myoglobin

84

what fibres is coloured red

oxidative

85

What diameters do glycolytic fibres have

large

86

What do glycolytic fibres have an increase of compared to oxidative

glycogen

87

What size of neutrons are easiest to exit first and example

small therefore slow oxidative fibres activated first

88

What do slow oxidative resist more of compared to fast glycolytic

fatigue

89

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

containing the most myofibrils

90

What fibres are last to be activated

Fast glycolytic fibres

91

increasing load results in increasing

number of active motor units

92

when the number of active motor units is increasing its called

recruitment

93

Neural control of muscle tension depends on

Frequency of AP’s
Recruitment of motor units

94

What do muscles need to be able to survive

base line level of stimulation

95

what is denervation atrophy and what can be the cause

Muscle wastage due to destroyed nerve or NMJ

96

when muscle is not used what happens

Disuse atrophy

97

What is an increase in muscle mass called

Hypertrophy

98

How does exercise cause hypertrophy?

Proteins are taking up to repair muscle damage

99

What is smooth muscle innervated by

autonomic NS

100

Where does smooth muscle exist

in hollow organs
eg. GI tract, uterus, airways, ducts

101

Structure of smooth muscle

spindled shape
mononucleate

102

What muscle can divide through life

smooth muscle

103

How are filaments arranged in smooth muscle

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

104

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

calmodulin

105

What activates myosin light chain kinase

calcium calmodulin complex

106

What does activated myosin light chain kinase do in smooth muscle

phosphorylates myosin x bridge with ATP

107

How does smooth muscle relax

dephosphorylation of X-bridges

108

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

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

109

What muscle are only some sites activated by Ca2+

smooth muscle

110

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

all

111

What muscle has the greatest range and control

smooth muscle

112

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

grade the contraction

113

What does it mean than smooth muscle has a tone

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

114

What factors affect the activity of contraction

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

115

What are the two types of smooth muscle

single unit or multi unit

116

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

single unit

117

What muscle type responds to stretch

single unit

118

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

signals travel between cells
contract synchronously

119

Smooth muscle sing unit fibres may contain what

pacemakers

120

examples of multiunit fibres

hair, airways, large arteries

121

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

single unit