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Anatomy of muscles Flashcards

1
Q

What are 3 different types of muscles?

A

Skeletal
Cardiac
Smooth

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2
Q

what is skeletal muscle made of ?

A

Muscle fibres (MYOCYTE/ Muscle cell)

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3
Q

What are muscle fibres made of?

A

Myofibrils

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4
Q

What do myocytes have?

A

nuclei

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5
Q

What is Epimysium?

A

connective tissue layer around muscle

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6
Q

What is Perimysium?

A

layer of connective tissue around Fascicle

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7
Q

What is Fascicle ?

A

bundles of muscle fibres inside muscle

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8
Q

What is Endomysium?

A

layer of connective tissue around each muscle fibre

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9
Q

What are Satellite cells?

A

stem cells of muscle between basal lamina

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10
Q

what does connective tissue form?

A

supporting tissue so blood vessels/nerves can run in

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11
Q

are skeletal muscle fibres multinucleated?

A

YES

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12
Q

How are muscle fibres formed?

A

myoblasts fusing together

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13
Q

What are myofibril composed of?

A

Sarcomeres in series

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14
Q

Where does 1 sarcomere run from?

A

Z disk to adjacent Z disk

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15
Q

What is A Band?

A

distance between thick filament of same sarcomere

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16
Q

Does the Width of A band change?

A

NO

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17
Q

What is I band?

A

thin filaments , distance between ends of different sarcomeres

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18
Q

What is H band?

A

region between thin filament protrusions

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19
Q

What happens in sarcomere on contraction?

A

I and H band Shortens

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20
Q

What is Z line?

A

where thin filaments attach

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21
Q

What is M line?

A

middle region

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22
Q

What powers muscle contraction?

A

cross-bridges

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23
Q

What determines the amount of contraction force?

A

amount of overlap between myofibrils

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24
Q

What is a thick filament?

A

myosin with tail and 2 heads

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25
Q

What activity does myosin head have?

A

ATPase- hydrolyse ATP to ADP+Phosphate for Actin binding

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26
Q

When does Myosin bind to actin ?

A

Power stroke

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27
Q

When is Actin released from ?

A

Hydrolysis of ATP

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28
Q

When does recovery stroke occur?

A

when actin is released

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29
Q

what do 2 heavy chains in the tail form?

A

coiled coil

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30
Q

What is 2 globular head formed from?

A

2 light chains each

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31
Q

How many light chains in myosin?

A

4 light chains

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32
Q

How does head bind to actin?

A

2 motor domains

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33
Q

What are 2 types of light chain?

A

Regulatory and Essential

34
Q

What is myosin arrangement?

A

anti parallel

35
Q

What do myosin tails assemble into?

A

thick filaments

36
Q

What is major protein in thin filament?

A

ACTIN

37
Q

What other proteins in thin filaments?

A 
Tropomyosin
Troponin
Nebulin
Alpha Actinin
Myosin
38
Q

where are thin filaments anchored ?

A

Z Disc

39
Q

What are barbed ends in Z disc cross linked by?

A

Alpha actinin

40
Q

Where are pointed ends in M line capped by?

A

Tropomodulin protein

41
Q

What is barbed end capped by ?

A

Capping protein T

42
Q

What do capping proteins do?

A

regulate length of the precise filaments and ensures right polarity

43
Q

What polarity does barbed end in Z disk match?

A

half of the thick filament

44
Q

What do cross bridges on myosin filament do to actin?

A

pull thin filament into middle of sarcomere

45
Q

What does force of contraction depend on?

A

sarcomere length

46
Q

What is the plateau region in sarcomere shortening?

A

full overlap of thick and thin filaments

47
Q

What is the structure of Tropomyosin?

A

alpha helical coiled coil

48
Q

How many actin subunits for 1 tropomyosin?

A

7

49
Q

What does Ca2+ bind to?

A

troponin and tropomyosin moves from myosin binding site

50
Q

How many actin subunits for 1 troponin?

A

7

51
Q

What happens at low Ca2+?

A

actin binding sites for myosin are blocked

52
Q

What happens at high Ca2+?

A

contraction - binds to TnC of troponin and tropomyosin moves across actin
- myosin binding site on actin is exposed

53
Q

What is Titin? (largest protein in body from Z to M line?

A

Carries tension from 1 sarcomere to another

54
Q

What titin regulate?

A

thick filament length and restores overlap

55
Q

What does Nebulin do?

A

bind across thin filament and regulate thin filament length

56
Q

What does the Sarcolemma have?

A

T tubules

57
Q

what are T tubules associated with?

A

Sarcoplasmic reticulum

58
Q

When is Ca2+ released from Sarcoplasmic reticulum?

A

when muscle is depolarised

59
Q

What does Ca2+ bind to?

A

troponin

60
Q

What is Calsequesturin ?

A

Hold Ca2+ in Sarcoplasmic reticulum cisterna

61
Q

Where does Action potential pass in depolarisation of muscle fibres?

A

t tubules to Ca2+ stores

62
Q

How is action potential in nerve terminal transmitted to muscle ?

A

acetylcholine released and bind to receptors in membrane

63
Q

What is DHPR (dihydropyridine) receptor?

A

on T tubules and Ca2+ channel

64
Q

What does DHPR activate?

A

a RYR (ryanodine receptor) so release Ca2+ from SR

65
Q

What is RYR?

A

Ca induced Ca release receptor so

66
Q

How is Ca2+ removed from sarcoplasm after contraction?

A

ATP dependant Ca2+ pump and back into Sarcoplasmic reticulum

67
Q

How does the muscle stay relaxed?

A

low Ca2+ by ATP pumps in Sarcoplasmic reticulum

68
Q

What nervous system causes muscle contraction?

A

Sympathetic nervous system

69
Q

What is released at neuromuscular junction?

A

Acetyl choline - binds to nicotinic cholinergic receptors so action potential within Sarcolemma
- AP down T tubules and activates DHPR and so RyR so Ca2+ spike

70
Q

What does Ca2+ spike cause?

A

conformational change in Troponin Tm unit so myosin binding and sarcomere shortening

71
Q

What happens when frequency of AP is increased?

A

stronger contraction since summation of tension

72
Q

What happens if AP are too frequent?

A

Fused tension so muscle cant relax

73
Q

Why does muscle twitch happen?

A

delay for contraction since time for Ca2+ to bind to troponin

74
Q

What do large motor neurones innervate?

A

larger motor units

75
Q

What are ATP sources?

A

Creatine Phosphate
Glycolysis
Oxidative Phosphorylation

76
Q

What the type of Muscle Fibres?

A

Type 1 fibres - slow and anaerobic

Type 2 fibres- fast and anaerobic

77
Q

What are the transmissions of forces?

A

longitudinal

Lateral

78
Q

What is longitudinal trans. of force along fibre?

A

myosin crossbridges and titin carry tension from one sarcomere to the next

79
Q

What is Lateral trans. of force along fibre?

A

Costamere link Z disk to sarcolemma

80
Q

What do the Myofibrillar proteins have?

A

cytoskeleton so all sarcomeres connected

HEART (11 decks)

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