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muscle tissue Flashcards

wk 5

1
Q

What are the three types of muscles?

A

Skeletal, cardiac and smooth

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2
Q

What are the functions of skeletal muscle?

A

movement, heat production, protection and posture

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3
Q

what is the structure of Skeletal tissue?

A

Cylider shaped. striated multiple nuclei, voluntary movements

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4
Q

Describe the muscle fibres of skeletal muscle tissue.

A

Striated appearance (thick and thin), hundreds of myoblasts fused together= can hypertrophy and last long time

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5
Q

Describe the actions and structure of Cardiac muscle fibres.

A

Actions
allow action potnetial spread
cntrcations last longer than skeletal

structure
Connect via desmosomes and gap junctions
Contract as single unit
More mitochondria = larger

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6
Q

How does cardiac fibres connect?

A

gap junctions and desmosomes

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7
Q

How does smooth fibres connect?

A

gap junctions

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8
Q

Describe the actions and structure of smooth msucle fibres

A

Actions

-allow action potentail spread

-contract as single unit

Structure

thick and thin filaments

(thin filamnets attach to dense bodies)

No regular pattern

No transverse tubules

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9
Q

What are the properties of muscles?

A

Contractibility, excitability, extensibility and elasticity

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10
Q

What does the arrangment of fascicles affect?

A

power and range of motion

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11
Q

What are the different types of fascicular arrangements?

A

Parallel, fusiform, circular, triangular, unipennate, bipennate and multipennate

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12
Q

What is the general structure of skleteal muscle?

A

Contractile proteins –> myofilaments –> myofibrils –> muscle cells –> arranged in fascicles (or layers) –> whole muscle

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13
Q

What are the three dense irregular connective tissue that allows muscles to communicate?

A

Epimysium, perimysium and endomysium.

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14
Q

What is epimysium and what does it do?

A

innermost dense irregular connective tissue. surrounds each individual muscle fibre

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15
Q

What is perimysium and what does it do?

A

Dense irregular connective tissue that surrounds fascicles (fibres bound together)

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16
Q

What is endomysium and what does it do?

A

Outermost dense irregular connective tissue, covers muscles fibres, thinner and more delicate

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17
Q

How are muscle cells formed?

A

via the fusion of myoblast cells

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18
Q

Can muscle fibres undergo cellular division?

A

no

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19
Q

What does sarcoplasmic reticulum do?

A

Stores calcium and wrapas around EACH muscle fibre

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20
Q

What is a sarcolemma?

A

Plasma membrane that encloses each muscle fibre

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21
Q

What is a sarcomere?

A

Smallest functional contractile unit of muscle

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22
Q

Describe the relationship between sarcomeres and myofibrils.

A

Myofibrils are a straited muscle organelle that is built up from sarcomeres.

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23
Q

what are the myofilaments within myofibril?

A

actin- thin
myosin- thick

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24
Q

What is the role of Z discs?

A

separate sarcomeres and anchor the thin filaments

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25
Q

what is the sliding theory?

A

Contraction occurs by the sliding of the thin filaments over the thick filaments – creating tension and producing muscle activation (contraction).

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26
Q

What is needed for muscle contraction?

A

Acetylcholine (ACh)

Calcium

ATP

Action and myosin

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27
Q

Where is acetylcholine (ACh) released from?

A

motor neuron

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28
Q

Where is calcium released from?

A

sarcoplasmic reticulum

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29
Q

What is the first step of muscle contraction?

A

Nervse impulse stimulates ACh release ate neuromusclar junction.

ACh binds to receptor

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30
Q

What is the second step of muscle contraction?

A

Action potential down Sarcolemma and T-Tubels

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31
Q

What is the third step of muscle contraction?

A

Ca released from Sarcoplasmic reticulum

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32
Q

What is the fourth step of muscle contraction?

A

Calcium binds to Troponin and removes block action f tropomyosin

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33
Q

What is the fifth step of muscle contraction?

A

Active site on actin exposed. myosin head binds and allows contraction

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34
Q

what are the components of a neuromuscular junction?

A

Synaptic bulb end
Synaptic vesicles
Motor end plate
synaptic cleft
ACh receptor
Acetylchokinesterase (AChE)

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35
Q

What is a synaptic bulb end?

A

expanded end of neuron

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36
Q

What is a synaptic vescicle?

A

membrane bound sac filled with ACh

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37
Q

What is a motor end plate?

A

at end of sarcolemma that has folds and indentations to increase SA

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38
Q

what is a Synaptic cleft?

A

the narrow space that separates synaptic knob and motor end plate

39
Q

Where are ACh receptors?

A

in motor end plate

40
Q

What is Acetylcholinesterase (AChE)

A

an enzyme that rapidly breaks down ACh

41
Q

What does a neuromuscular junction do?

A

Stimulate skleteal muscle fibres to contract

42
Q

What forms the synapse?

A

synaptic end bulb and sarcolemma

43
Q

What is the small gap that separates synapse called?

A

synaptic cleft

44
Q

What causes the influc of calcium?

A

nerve impulses

45
Q

What does increases Ca stimulate?

A

release of ACh (synaptic vesiciles –> synaptic cleft)

46
Q

What are the actions of the neurmuscular junction (4 steps)

A

1- ACh relased from synaptic vescile

2- ACh binds to ACh receptor on motor end plate

3-muscle action poetial propagates through sarcolemma and t-tubles

4- ACE breaks down ACh

47
Q

What does does ACh bind?

A

ACh receptors in motor end plate of muscle fibres

48
Q

What does the binding of ACh receptors cause?

A

opening of ion channels to allow Na to enter muscle

49
Q

What does the precence of Na allow?

A

generation of action potential through sarcolemma and t-tubules

50
Q

what muscle tissue is multinucleated and why?

A

Skeletal- developmental = cells merge together

51
Q

where are the nuclei in skeletal muscle tissue and why?

A

Squished to. the side because there is a lot of myofibrail.

52
Q

What joins two cells together?

A

intercalated disc

53
Q

what is the function of smooth muscle and where is it?

A

Movement through organs.

Walls of hallow organs, conducting organs, intestines, stomach and urinary bladder

54
Q

What type of muscle is responsible for peristalsis?

A

smooth muscle

55
Q

what are the three layers in the mucosa?

A

Epithelium, lamina propria (loose aerolar) and muscularis mucosae (smooth)

56
Q

What are the three components of muscularis external?

A

larger muscles, outer longitudinal layer and inner circular layer

57
Q

What are the connective tissues in cardiac fibres?

A

endomysium and perimysium

58
Q

what are the connective tissues in skeletal fibres?

A

epimysium, perimysium and endomysium

59
Q

what is the connective tissue in smooth muscle fibres?

A

endomysium

60
Q

Where are fascicles and what is it wrapped up by?

A

Within the muscle - perimysium

61
Q

what is the name of the organelle that allows muscles to contract?

A

myofibril

62
Q

What is the contracting unit?

A

the sarcomere

63
Q

What does the Z disc attached to?

A

thin filaments (actin)

64
Q

What does the M line attach to?

A

thick filaments (myosin)

65
Q

What does the M line do?

A

anchors thick filaments

66
Q

relate cardiac structure to function?

A

Lots of sarcomeres - contract as single units (not whole units) and passes rapid electrical impulses via the gap junctions

67
Q

relate the structure to the function of skeletal muscle.

A

straied= greater length for contraction and multiple nuclei allow to contract as one whole unit (not use gap junctions)

68
Q

what is the function of the epimysium?

A

protects muscles from friction against other muscles and fibres

69
Q

What is the function of perimysium?

A

adds to the resistance of muscle to tensile forces

70
Q

What is the function of endomysium?

A

separates single muscle fibres from one another

71
Q

what is a fascicle?

A

Bundle of muscle fibres wrapped in perimysium.

72
Q

How does skeletal muscle fibres become multinucleated?

A

fusion of myoblasts

73
Q

What is the basic cellular unit of skeletal muscle called a fibre?

A

because they are long a cylindrical

74
Q

What muscle tissue type does not have any sacromeres?

A

smooth tissue. Allows for slow rhythmic contractions

75
Q

describe the structure of musce fibre cell.

A

Long cylindrical cell covered by endomysium and sarcolemma; contains sarcoplasm, myofibrils, many peripherally located nuclei, mitochondria, transverse tubules, sarcoplasmic reticulum, and terminal cisterns. The fibre has a striated appearance.

76
Q

Where are the mitochondria located in the skeletal tissue located?

A

close to the sarcoplasmic reticulum

77
Q

why does the straited appearance in skeletal muscle fibres occur?

A

precise alignment of myofilaments within the cells organised into myofibrils.

78
Q

what are the major types of myofilaments within skeletal muscle cells?

A

Actin (thin) and mysoin (thick)

79
Q

What is the first step of sliding filament theory?

A

Action potential crosses neuromuscular junction
-muscle cell depolarises
-wave through sarcolemma
-spreads down t-tubels into sarcoplasmic reticulum

80
Q

What is the second step of sliding filament theory?

A

Calcium channel opens
-Sacroplasmic reticulum stores calcium
-depolarisation releases Ca into sarcoplasm

81
Q

what is the third step of the sliding filament theory

A

Ca unlocks tropin and releases the tropomyosin to change the shape of the protein and allow the Myosin head to attach to the actin.

82
Q

What is the fourth step of the sliding filament theory?

A

ATP converts to ADP and Pi

83
Q

what is the fifth step of the sliding filament theory?

A

Power Stroke- ATP releases energy to change the angle of the myosin head

Actin slides over the myosin

sarcomere compacted and muscle contracts

84
Q

What is the 6th and 7th step

A

Actin-myosin bridge breaks - ATP binds and it all repeats

85
Q

What is the function of actin?

A

mechanical support, determines cell shape and allows movement

86
Q

What is the function of myosin?

A

converts chemical energy in the form of ATP to mechanical energy, thus generating force and movement.

87
Q

What are the two regulatory proteins?

A

Tropomyosin
Troponin

88
Q

What are the functions of tropomysin?

A

component of thin filament; when skeletal muscle fibre is relaxed, tropomyosin covers myosin- binding sites on actin molecules, thereby preventing myosin from binding to actin.

89
Q

whis the function of troponin?

A

omponent of thin filament; when calcium ions (Ca21) bind to troponin, it changes shape; this conformational change moves tropomyosin away

90
Q

What is titan and its function?

A

structural protein- connects Z disc to M line of sarcomere, thereby helping to stabilise thick filament position; can stretch and then spring back unharmed,

91
Q

what is Dystrophin and what is its functions?

A

structural protein - links thin filaments of sarcomere to integral membrane proteins in sarcolemma,

help reinforce sarcolemma and help transmit tension generated by sarcomeres to tendons.

92
Q

Why don’t smooth muscle cells appear to be straited and what is the arrangement of the contractile elements?

A

thick and thin filaments don’t arrange in sarcomeres

93
Q

Describe the interactions between the I band and A band of the sarcomere.

A

The A band slides along the I band and interacts with myosin and actin to allow for the muscle to contract.

94
Q

Why does the A band overlap?

A

allows the globular heads of myosin can reach up and bind

CTL (11 decks)

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