Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Semester 2 Year 1 > Sarcomere Structure > Flashcards

Sarcomere Structure Flashcards

1
Q

What is whole muscle made up of?

A

Bundles of fascicle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is each fascicle made up of?

A

Series of fibres

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is each muscle fibre made up of?

A

Myofibrils

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is each myofibril made up of?

A

Repeating units (sacromeres)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What cells does muscle start developing from?

A

Myosatellite cells - mesenchymal cells in each myotome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What do myosatellite/mesenchymal cells give rise to?

A

yoblasts - immature muscle cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are my oblasts like?

A

Mononuclear

Skeletal muscle precursors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What do myoblasts mature into?

A

Myocytes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are myocytes like?

A

Multinucleated cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Muscle development:

A

Myosatellite cells -> myoblasts -> myocytes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What do myotubes form?

A

Myofilaments by synthesising myosin and actin (contractile proteins)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What type of process is the formation of myofilaments?

A

Regulated process of differentiation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What inhibits formation of myofilaments?

A

Myostatin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How are sacromeres organised?

A

Within skeletal and cardiac muscle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Apparently of sacromeres:

A

Striped appearance - striated

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is a sacromere?

A

Portion of myofibril between two successive z discs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What’s the difference from one z disc to another z disc called?

A

One sarcomere

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What do contractile proteins consist of?

A

Thin filaments (actins)

Thick filaments (myosin)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What does I band represent?

A

Actin filaments

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What does A band represent?

A

Myosin filaments

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What’s a H band?

A

Gap between successive actin filaments

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What makes up a Z-disc?

A

a-actinin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is a-actinin?

A

Actin-binding protein

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Why is a-actinin important?

A

Binds ends of thin filaments to Z-discs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What’s Titin?

A

Largest protein

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Why is Titin important?

A

Binds ends of thick filaments (M line) to Z discs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What do different Titin isoforms forms result in?

A

Different elasticity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What can Titin be compacted to?

A

A spring

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What is Nebulin?

A

Actin-binding protein

Large protein

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

Where is nebulin localised to?

A

I-band

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

Why is nebulin important?

A

Regulates thin filament length during sarcomere assembly - a ruler

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

What’s Dystrophin?

A

Large protein

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

Cross sections: I band

A

Thin filaments only

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

Cross sections: H zone

A

Tick filaments only

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

Cross sections: M line

A

Thick filaments linked with accessory proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

Cross sections: Outer edge of A band

A

Thick and thin filaments overlap

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

What proteins do thin filaments consist of?

A

Actin

Tropomyosin

Troponin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

What is the backbone of a thin filament like?

A

Double stranded a-helical polymer of actin molecules

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

What is the polymer of actin molecules in the thin filament also called?

A

F-actin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

What does tropomyosin consist of?

A

2 identical a-helices

Coil around groove formed by actin

41
Q

What type of protein is tropomyosin?

A

Regulatory protein

42
Q

What does tropomyosin allow?

A

Overlap of binding sites on actin for myosin

43
Q

What does tropomyosin do in relaxed state?

A

Inhibit interaction of actin and myosin

44
Q

What does TnT do in troponin complex?

A

Binds to tropomyosin

45
Q

What does TnI do in troponin complex?

A

Binds to actin

Inhibits contraction

46
Q

What does TnC do in troponin complex?

A

Binds calcium

47
Q

Why does calcium bind to troponin?

A

To regulate skeletal muscle contraction

48
Q

How does calcium binding to troponin regulate skeletal muscle contraction?

A

Moves tropomyosin away + allows myosin to interact with actin

49
Q

What are thick filaments?

A

Bipolar assemblies of multiple myosin-II molecules

50
Q

What does each myosin-II molecule consist of?

A

2 intertwined heavy chains

2 regulatory light chains

2 essential light chains

51
Q

What are the 2 regulatory light chains called in myosin-II molecule?

A

MLC-2

52
Q

What does MLC-2 do?

A

Regulates ATPase activity of myosin

53
Q

What are the 2 essential light chains called in myosin-II molecule?

A

MLC-1

54
Q

What does MLC-1 do?

A

Stabilises myosin head

55
Q

Where are MLC-1 and MLC-2 found in heavy chain?

A

Hinge region

56
Q

What does the tail of thick filaments consist of?

A

Two intertwined a-helical heavy chains

57
Q

What happens if calcium isn’t present?

A

Regulatory proteins inhibit actin-myosin interactions

58
Q

What’s necessary in cross-bridge cycle?

A

Calcium

59
Q

What is the key calcium sensitive regulator?

A

Troponin C

TnC

60
Q

What binding sites does troponin C have?

A

2 high affinity and 2 low affinity

61
Q

What do the 2 high affinity binding sites on TnC do?

A

Help in binding TnC to thin filament

62
Q

What do the 2 low affinity binding sites on TnC do?

A

Binds calcium

63
Q

What happens to Troponin complex when calcium binds to it?

A

Conformational change

64
Q

What does the conformational change in troponin do?

A

Troponin I (TnI) moves away from actin filament

Troponin T (TnT) pushes tropomyosin away from actin binding site

65
Q

What troponin binds to calcium?

A

TnC

66
Q

What troponin binds to actin?

A

TnI

67
Q

What troponin binds to tropomyosin?

A

TnT

68
Q

WHat happens when calcium concentration falls?

A

Calcium disassociates from TnC - reverses conformational change

69
Q

What happens when actin binding site exposed?

A

Myosin head can now bind to actin

70
Q

What must happen before myosin binds to actin?

A

Must hydrolyse ATP to ADP and Pi

Changes to 90 degree angle -> thick and thin filament bind together

71
Q

What happens after myosin is bound to actin?

A

ATP and Pi are released from myosin head

Myosin head changes to 45 degree angle

72
Q

Why is myosin head changed back to 45 degree angle after bound to actin?

A

To move the thin filaments towards eachother

73
Q

What is power stroke?

A

When the thin filaments are moved towards eachother

74
Q

What happens after thin filaments are moved towards eachother?

A

ATP binds to myosin head

Thin filament is released from thick filament

Calcium also released

75
Q

What does the removal of calcium from TnC cause?

A

Tropomyosin closes binding site to myosin

76
Q

What happens to the bands in sacromere shortening?

A

I band and H zone shorten

Z lines move closer together

A band constant

77
Q

What’s the neuromuscular junction also known as?

A

Motor endplate

78
Q

What are contractions of skeletal muscle initiated by?

A

Cerebral cortex

79
Q

What does the cerebral cortex act by in skeletal muscle contraction?

A

a-motor neurons

80
Q

What forms the neuromuscular junction?

A

Motor neurons flattened to form motor endplate

81
Q

What happens after acetylcholine is released into synaptic cleft?

A

Attached to Nicotinic Acetylcholine receptors

82
Q

What breaks down acetylcholine in synaptic cleft?

A

Acetylcholinesterase

83
Q

How are transverse tubules formed?

A

When plasma membrane of muscle cells invaginate into muscle cell

84
Q

Where to T tubules penetrate muscle?

A

Junctions of I and A bands in each sarcomere

85
Q

What’s along each T-tubule?

A

2 cisternae of sarcoplasmic reticulum

86
Q

Where is calcium stored in T-tubules?

A

Sarcoplasmic reticulum

87
Q

What’s a triad?

A

T tubule and 2 cisternae

88
Q

What happens to action potential after reaching motor end plate?

A

Propagates along skeletal muscle membrane and down T tubules

89
Q

What happens after AP goes down T-tubules?

A

Depolarisation

Opens voltage gated L-type calcium channels

90
Q

How are voltage gated L-type calcium channels organised in T-tubules?

A

In tetras - groups of 4

91
Q

Another name for L-type calcium channel:

A

Dihydropyridine (DHP) receptor

92
Q

What does AP do to DHP receptor?

A

Conformational change

Activates Calcium-release channel

93
Q

ANother name for calcium-release channel:

A

Ryanodine receptor

94
Q

WHat does an increase in calcium result in?

A

Activation of TnC and cross-bridge cycling

95
Q

What must happen for contraction to cease?

A

Remove calcium

96
Q

Minor way for termination of contraction:

A

Sodium-calcium exchanger

Calcium pump at plasma membrane

Both remove calcium from cell

97
Q

Major way for termination of contraction:

A

Calcium reuptake into sarcoplasmic reticulum by SERCA-type calcium pump

98
Q

What happens when SERCA-type calcium pump reuptake calcium?

A

Calcium binds to calsequestrin and calreticulin proteins in skeletal muscle

Semester 2 Year 1 (12 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions