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Cell and Tissue Structure > Muscle excitable tissue L2 > Flashcards

Muscle excitable tissue L2 Flashcards

1
Q

What are the 4 tissue types?

A

Epithelial, Muscle (excitable), Nervous (excitable), Connective (cells, fibres, matrix)

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2
Q

How much of the total body weight does muscle form?

A

50%: 40% skeletal muscle and 10% smooth and cardiac muscle

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3
Q

What functions do muscles preform. Hint there should be 5 functions.

A

They contract, they generate heat, they generate motion, they generate force, and they provide support

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4
Q

What type of muscle is skeletal?

A

Striated, voluntary muscle

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5
Q

What type of muscle is cardiac?

A

Striated, involuntary muscle

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6
Q

What type of muscle is smooth?

A

Unstriated, involuntary muscle

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7
Q

Where are the nuclei located on skeletal muscle?

A

Peripheral nuclei

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8
Q

Is skeletal muscle strong or weak?

A

strong

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9
Q

What type of contractions occurs with skeletal muscle?

A

Short contractions

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10
Q

What type of contractions occurs with cardiac muscle?

A

Continuous contractions

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11
Q

Where are the nuclei located on cardiac muscle?

A

Centrally

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12
Q

Is cardiac muscle strong or weak?

A

Strong

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13
Q

Is smooth muscle stronger or weaker?

A

weaker

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14
Q

What type of contractions are associated with smooth muscle?

A

Continuous contractions

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15
Q

Where are the nuclei located with smooth muscle?

A

Centrally

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16
Q

What can a single skeletal muscle cell also be called and why?

A

A single skeletal muscle cell is also called a muscle fibre because of its greater length than width

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17
Q

What is the chemical composition of skeletal muscle?

A

Proteins (20%) (either as enzymes or for muscle Control) Lactic Acid (in muscle that has undergone fatigue)
ATP, ADP
Myoglobin (stores O2 & gives colour to the muscle)

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18
Q

What is the length of skeletal muscle cells?

A

Up to 75,000 µm or 2.5 feet

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19
Q

What is the diameter of skeletal muscle cells?

A

From 10-100 micrometres

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20
Q

What is the shape of skeletal muscle cells?

A

Elongated and cylindrical

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21
Q

Do skeletal muscle cells have an outer membrane?

A

Yes it is called sarcolemma

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22
Q

Are there nuclei and organelles in skeletal muscle cells?

A

Yes they are present. Mitochondria and E.R

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23
Q

What is the myoneural junction?

A

It is the synapse between motor neuron and muscle fibre

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24
Q

What neurotransmitter is associated with the myoneural junction?

A

Acetylcholine

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25
Q

What is a motor unit?

A

It is all the muscle fibres innervated by a single neuron

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26
Q

What is the innervation ratio of motor neuron : muscle fibres?

A

1:100 to 1:2000

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27
Q

What are the innervation ratios of eye motor neurons and gastrocnemius?

A

Eye motor neurons 1:23, Gastrocnemius 1:1000

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28
Q

What is the motor end plate of the myoneural junction?

A

It is a specialised area of sarcolemma under the axon terminal

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29
Q

What is the sarcolemma?

A

The plasmalemma of muscle cells. External to this cell
membrane is a well developed basement membrane

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30
Q

What is the sarcoplasm?

A

It is the cytoplasm of muscle cells excluding the myofibrils.

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31
Q

What is the epimysium?

A

A thick layer of collagenous connective tissue that
separates large bundles of muscle.

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32
Q

What is the perimysium?

A

A collagenous connective tissue that separates
smaller bundles of muscle cells called fascicles.

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33
Q

What is a fasicle?

A

It is a bundle of muscle cells bounded by perimysium.

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34
Q

What is the endomysium?

A

It is a thinner layer of connective tissue that separates
individual muscle cells.

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35
Q

How do muscle fibers develop?

A

They develop through the fusion of mesodermal cells called myoblasts

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36
Q

What do collagen fibres do in skeletal muscle organisation?

A

They blend to form tendon at end muscle

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37
Q

What do tendons do in skeletal muscle organisation?

A

Tendons attaches skeletal muscle to bone

38
Q

What type of muscle are muscle fibres found?

A

In skeletal and cardiac muscle

39
Q

What are muscle cells. Hint Fibres

A

Muscle cells make individual muscle fibers which are cells that are large and elongated and have multiple peripheral
nuclei that produce voluntary contractions

40
Q

What are myofibril’s made up of?

A

Myofilaments

41
Q

What are myofilaments/sarcomeres composed of?

A

Thick filament called myosin and thin filaments called actin

42
Q

Why are striations formed?

A

Due to alignment of filaments of myofibrils

43
Q

What happens during contraction?

A

The sarcomere shortens and myosin binding protein C binds myosin and actin

44
Q

What is G-actin?

A

G-actin is the monomer which will form the thin
filament (actin). It is a protein with a molecular weight of
43 KDa. It has a prominent site for cross-linkage with
myosin.

45
Q

How are actin - thin filaments formed?

A

G-actin goes to F-actin which is a long polymerised G-actin that is 6-7nm long and double stranded in structure and that goes to thin filaments.

46
Q

What are 2 regulatory proteins of the muscles?

A

Tropomyosin and Troponin

47
Q

What is troponin?

A

It is a globular protein complex that is made up of 3 polypeptides: Troponin C,I,T which forms part of thin filaments.

48
Q

What does troponin C do?

A

Binds to Ca^2+

49
Q

What is the function of troponin I?

A

It is inhibitory in function

50
Q

What is Troponin T?

A

It is attached to tropomyosin

51
Q

What is tropomyosin?

A

A rod like protein with a molecular weight of 70kDa. It has 2 chains of alpha and beta chains. It forms part of thin filaments of muscle

52
Q

What does tropomyosin do under resting conditions?

A

It covers the site for myosin attachment on F-actin molecule

53
Q

What does the protein Nebulin do in regards to thin filaments?

A

Nebulin provides elasticity to the sarcomere

54
Q

What does the protein Titin do in regards to thin filaments?

A

Titin is the largest known protein in the body. It contributes to the contraction of skeletal muscle

55
Q

What length are thin filaments?

A

1 µm

56
Q

What is the diameter of thin filaments?

A

5-8nm

57
Q

What is the number of G-actin mol?

A

300-400

58
Q

What are thick filaments consistent of?

A

2 symmetrical halves that are mirror images of each other. The chief constituent is myosin.

59
Q

What is the molecular weight of myosin?

A

480 KDa

60
Q

Describe the molecule myosin?

A

Its molecule has 2 ends, a globular end having 2 heads and a rod like tail. It has 6 peptide chains: 2 identical heavy chains with 200 KDa each and 4 light chains with 20 KDa each

61
Q

What are the 2 binding sites on the myosin molecule?

A

Binding site for actin and ATPase site

62
Q

3 things about the innervation of cardiac muscle?

A

The innervation is involuntary, the pacemaker cells coordinate contraction of tissue and there is electrical conduction (Purkinje fibres and gap junctions)

63
Q

Is cardiac muscle resistant to fatigue?

A

Yes

64
Q

Does cardiac muscle have an all or none feature?

A

Yes (“twitch”)

65
Q

What is the name for cardiac muscle cells?

A

Cardiocytes

66
Q

What do cardiocytes contain?

A

Myofibrils which are striated

67
Q

Where do cardiocytes cells contact each other?

A

At intercalated disks

68
Q

What do cardiocytes cells bind together by?

A

Gap junctions and desmosomes

69
Q

Where is the body location of skeletal muscle?

A

Attached to bones or, for some facial muscles to skin

70
Q

What is the cell shape and appearance of skeletal muscle?

A

Single, very long, cylindrical, multinucleate cells with very obvious striations

71
Q

Where is the body location of cardiac muscle?

A

Walls of the heart

72
Q

Where is the body location of smooth muscle?

A

Mostly in walls of hollow visceral organs (other than the heart)

73
Q

What is the cell shape and appearance of cardiac muscle?

A

Branching chains of cells; uninucleate, striations; intercalated disks

74
Q

What is the cell shape and appearance of smooth muscle?

A

Single, fusiform, uninucleate; no striations

75
Q

Is the innervation of smooth muscle involuntary?

A

Yes, autonomic innervation

76
Q

Is the innervation of smooth muscle stimulatory or inhibitory?

A

It is dual, both stimulatory and inhibitory

77
Q

Is the smooth muscle innervation graded?

A

Yes it is graded and spreading and continuous contraction

78
Q

Describe multi-units of smooth muscle:

A

Each cell is innervated with variable force for example in the airways, and large arteries

79
Q

Describe single-units of smooth muscle:

A

Very few cells are innervated. There is synchronous contraction which is myogenic. For example in the gut and uterus

80
Q

Smooth muscle is located in the organs of….

A

Cardiovascular system (vessel walls), respiratory system, digestive system, urinary system, reproductive system and inside the eyes

81
Q

What are the function and features of smooth muscle?

A

Little/weak contractile apparatus, long, slender, spindle shaped cells with single central nucleus and is nonstriated

82
Q

What is the speed of contraction of skeletal muscle?

A

Slow to fast

83
Q

What is the regulation of contraction in skeletal muscle?

A

Voluntary via nervous system controls

84
Q

What is the regulation of contraction in cardiac muscle?

A

Involuntary, the heart has a pacemaker and also nervous system controls and hormones

85
Q

What is the speed contraction of cardiac muscle?

A

slow

86
Q

What is the regulation of contraction in smooth muscle?

A

Involuntary with nervous system controls, hormones, chemicals, stretch

87
Q

What is the speed of contraction like in smooth muscle?

A

Very slow

88
Q

What are the connective tissue components of skeletal muscle?

A

Epimysium, perimysium and endomysium

89
Q

What are the connective tissue components of smooth muscle?

A

Endomysium

90
Q

What are the connective tissue components of cardiac muscle?

A

Endomysium attached to the fibrous skeleton of the heart

Cell and Tissue Structure (8 decks)

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