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Nerve-Physio > Intro/Skeletal Muscle Structure > Flashcards

Intro/Skeletal Muscle Structure Flashcards

1
Q

Muscle makes up ___ in men

A

42-47% of body mass.

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2
Q

Muscle makes up ___ in women

A

30-35%

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3
Q

Types of muscle

A

Skeletal
Smooth
Cardiacs

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4
Q

Each skeletal muscle is an organ. True or false?

A

True

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5
Q

Properties of the cells of the skeletal muscle

A
  • Long and cylindrical, in bundles
  • Multinucleate
  • Obvious Striations
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6
Q

Which muscle type carries our voluntary actions?

A

Skeletal

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7
Q

What are the skeletal muscle’s connective tissue components?

A
  • Endomysium
  • Perimysium
  • Epimysium
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8
Q

Skeletal muscles are found…

A

…attached to bones in the skeletal system

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9
Q

Endomysium is found…

A

…between fibers

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10
Q

Perimysium is found…

A

…surrounding bundles

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11
Q

Epimysium is found…

A

…surrounding whole muscle

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12
Q

Which tissue component of skeletal muscle covers the entire muscle?

A

Epimysium

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13
Q

Smooth muscle is found…

A

…in the walls of hollow organs like blood vessels and the GIT

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14
Q

Properties of the cells of smooth muscle

A
  • Uninucleate

- No striations

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15
Q

The movements of smooth muscle are voluntary. True or false?

A

False

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16
Q

Which muscle type possesses two layers of opposite orientation?

A

Smooth muscle

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17
Q

Muscle layers of smooth muscle

A

Circular

Longitudinal

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18
Q

Components of connective tissue in smooth muscle

A

Endomysium

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19
Q

Endomysium smooth muscle tissue

A

It surrounds cells

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20
Q

Properties of cells of cardiac muscle

A
  • Branching, chains of cells
  • Single Nucleated
  • Striations
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21
Q

Cardiac muscle cells are connected by…

A

…intercalated discs

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22
Q

Cardiac muscle movement - Involuntary or not?

A

Involuntary

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23
Q

The heart muscle is called…

A

Myocardium

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24
Q

Connective tissue component of cardiac muscle

A

Endomysium; it surrounds cells

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25
Q

A skeletal muscle fiber is an individual muscle cell. True or false?

A

True

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26
Q

Shape of muscle fibres

A

They are long and narrow in shape

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27
Q

Sarcolemma is…

A

…the plasma membrane of the muscle cell. It surrounds the sarcoplasm and has many nuclei (multi-nucleated)

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28
Q

The nuclei of the muscle cell are located…

A

…in the periphery of the muscle cell just beneath the sarcolemma

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29
Q

The organelle must abundant in skeletal muscle fibres is…

A

Mitochondria

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30
Q

Cellular levels of structures in the skeletal muscle fiber from 1 to 5 are…

A 
Sarcolemma
Sarcoplasm with organelles and proteins
Myofibrils and myofilaments
SR
T tubules
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31
Q

Why are there abundant mitochondria in skeletal muscle fibres?

A

High demand for energy (ATP) required for muscle contraction

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32
Q

What is myoglobin?

A

A protein with a high affinity for oxygen, just like haemoglobin

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33
Q

Function of myoglobin

A

It transfers oxygen from the blood to the mitochondria of the muscle cell

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34
Q

What are myofibirils?

A

A cylindrical bundle of contractile proteins, which are called myofilaments, within a muscle fiber

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35
Q

What are myofilaments? Where are they found?

A

They are contractile protein filaments that make up the Myofibrils, located in the sarcoplasm of the muscle cell

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36
Q

What are the names of the myofilaments of striated muscle cells?

A

–Actin – thin filament

–Myosin – thick filament

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37
Q

What is the Sarcoplasmic reticulum (SR)?

•Located where the SR ends, which is near the area where actin and myosin overlap
–The SR tubules and terminal cisternae store high concentrations of calcium, which is important in the process of skeletal muscle contraction

A

A saclike membranous network of tubules that are actually an elaborate form of smooth endoplasmic reticulum

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38
Q

SR surrounds ____ and contains ___

A

myofibril, terminal cisternae

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39
Q

Location of terminal cisternae on muscle fibre cells

A

They are located where the SR ends, which is near the area where actin and myosin overlap

40
Q

Functions of SR

A

The SR tubules and terminal cisternae store high concentrations of calcium, which is important in the process of skeletal muscle contraction

41
Q

Where are the transverse tubules (T-tubules) of skeletal muscle cells found?

A

They are invaginations found closely associated with SR and connected to the sarcolemma but penetrate the sarcolemma into the interior of the muscle cell

42
Q

Functions of T-tubules

A

They bring extracellular materials into close proximity of the deeper parts of the muscle fiber

43
Q

SR and T-tubules Function

A

–Activate skeletal muscle contraction when the muscle cell is stimulated by a nerve impulse
–Transmit nerve impulses from the sarcolemma to the myofibrils

44
Q

The sarcomere is…

A

An arrangement of myofilaments with alternating bands of light and dark areas due to the organization of the actin and myosin, resulting in a striated appearance

45
Q

What is smallest contractile unit of the muscle fiber?

A

Sarcomere

46
Q

The components of the sarcomere are…

A 
Z-lines
M-lines
A-bands
I-bands
Proteins
47
Q

Z line properties

A

-

48
Q

Actin is anchored by…

A

Z lines

49
Q

Thick myofilaments (myosin) are anchored by…

A

M lines

50
Q

Which two lines run perpendicular along the muscle fibres?

A

Z and M lines

51
Q

Thin actin filaments project in either direction off of a Z disc and cross the entire length of the sarcomere. True or false?

A

Not entirely true. It projects off but doesn’t cross the entire length.

52
Q

What is the H-Zone?

A

The lighter area within the A-Band that contains only myosin and contains the M line.

53
Q

The A-band spans the length of the myosin filament. True or false?

A

True

54
Q

There is no actin in the M band. True or false?

A

True

55
Q

The I band is…

A

… a light area composed of actin only. It contains the Z line, which is the border of the sarcomere

56
Q

Which is darker - A band or I band?

A

A-band

57
Q

The basic component of each actin myofilament is…

A

G-actin (globular actin)

58
Q

The actin myofilament consists of…

A

…two strands of G-actin molecules and myosin binding sites

59
Q

The two strands of G-actin molecules in actin are twisted together with…

A

…two regulatory proteins:
–tropomyosin
–troponin

60
Q

The sarcomere is broken up into three bands. True or false? What are they?

A

True. A band, two I bands

61
Q

Structure of Tropomyosin

A
  • Rod-shaped
  • Occupies the groove between the twisted strand of actin molecules
  • Blocks the myosin binding sites on the G-actin molecules
62
Q

Troponin structure

A

A complex of three globular proteins:
•One is attached to the actin molecule
•One is attached to tropomyosin
•One contains a binding site for calcium

63
Q

What are myosin cross bridges?

A

The myosin heads are known as cross-bridges because they can bind to and move along actin in the thin filament.

64
Q

Myosin is composed of…

A

…a rod-like tail and two globular heads

65
Q

What form the central portion of the myosin myofilament?

A

The tails

66
Q

Orientation of the two globular heads of the myosin molecule

A

They face outward and in opposite directions

67
Q

When does myosin interact with actin?

A

During contraction

68
Q

Binding sites on myosin

A

There are binding sites for both actin and ATP

69
Q

The ATP binding site for myosin contains…

A

The enzyme ATP-ase for the hydrolysis of ATP

70
Q

What is Titin?

A

It connects myosin to the Z-lines in the sarcomere

71
Q

Properties of Titin

A

–It is very elastic, able to stretch up to 3 times its resting length
–Important molecule because it is responsible for muscle flexibility

72
Q

Not all muscle fibers are the same physiologically. True or false?

A

True

73
Q

Criteria for muscle variation

A

–The predominant pathway utilized to synthesize ATP
–The amount of myoglobin
–Efficiency of ATPase

74
Q

Classification of muscle fibres based on ATP synthesis pathway

A
  • Oxidative fibers

* Glycolytic fibers

75
Q

Oxidative fibers properties

A
  • Predominantly aerobic pathways
    – Oxidative phosphorylation in the mitochondria
    – Fatigue-resistant fibers
76
Q

Glycolytic fibers properties

A
  • Predominantly anaerobic pathways
    –Glycolysis in the sarcoplasm
    –Fatigable fibers
77
Q

Classification of muscle fibres based on the amount of myoglobin present

A
  • Red fibers - high amounts of myoglobin

* White fibers - small amounts of myoglobin

78
Q

Classification of muscle fibres based on the efficiency of ATPase

A
  • Fast twitch fibers - decompose ATP rapidly

* Slow twitch fibers - decompose ATP slowly

79
Q

Slow-twitch, fatigue-resistant fibers properties

A

–Slow oxidative fibers, or red muscle fibers.
–Contain abundant myoglobin giving them their red color.
–Slow acting ATPase enzymes
–Abundant mitochondria
–Endurance type muscles
•Able to deliver strong, prolonged contractions.

80
Q

Slow-twitch, fatigue-resistant fibers properties depend upon aerobic pathways for production of ATP. True or false?

A

True

81
Q

Examples of slow-twitch, fatigue-resistant muscles

A

–Postural muscles - spinal extensors

–Anti-gravity muscles - calf muscle

82
Q

Gastrocnemius is not a slow-twitch, fatigue-resistant muscles. True or false?

A

False; it is.

83
Q

Fast-twitch fatigable fibers properties

A 
–Fast glycolytic fibers, or white muscle fibers.
–Contain small amounts of myoglobin
–Fast acting ATPase enzymes
–Few mitochondria
–Plenty of glycogen
–Extensive sarcoplasmic reticulum
84
Q

Fast-twitch fatigable fibres contract slowly. True or false?

A

False

85
Q

Fast-twitch fatigable fibres contract for limited periods of time. True or false?

A

True

86
Q

Which type of muscle fibres depends on anaerobic metabolism?

A

Fast twitch anaerobic metabolism

87
Q

Which muscle fibres are best suited for short duration, high intensity contractions?

A

Fast-twitch, fatigable fibres

88
Q

Fast twitch fatigable fibres rapidly releases and stores calcium ions contributing to rapid contractions. True or false?

A

True

89
Q

What are intermediate fibres?

A

Intermediate Fibers are fast-twitch fatigue-resistant fibers, fast and glycolytic fibers that lie between the red and white fibers

90
Q

What determines the muscle cell type?

A

The motor nerve that innervates the muscle cell

91
Q

A motor unit is…

A

A motor neuron and all of the muscle fibers it innervates

92
Q

All of the muscle cells in a single motor unit are of the same type. True or false?

A

True

93
Q

Which muscle fibre types are recruited first? Why?

A

Slow twitch fibers are recruited first because they are found in small motor units while fast twitch fibers are recruited last because they are found in large motor units

94
Q

People are genetically predisposed to have relatively more of one fiber type than another. True or false?

A

True

95
Q

Difference between marathon runners and sprinters

A

People who excel at marathon running have higher percentages of slow twitch fatigue resistant muscle fibers while people who excel at sprinting have higher percentages of fast twitch fatigable fibers

Nerve-Physio (8 decks)

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