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Zoology > Muscular System > Flashcards

Muscular System Flashcards

1
Q

muscle tissue is divided into 3 muscles:

A
  1. Skeletal Muscle
  2. Cardiac Muscle
  3. Smooth Muscle
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2
Q

____________ are attached to the skeletal system and allow us to move

A

Skeletal Muscle

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3
Q

6 Functions of Skeletal Muscles:

A
  1. Produce skeletal movement
  2. Maintain body position and posture
  3. Support soft tissues
  4. Guard body openings (entrance/exit)
  5. Maintain body temperature
  6. Store Nutrient reserves
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4
Q

Muscles have 3 layers of connective tissues:

A
  1. Epimysium
  2. Perimysium
  3. Endomysium
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5
Q

Epimysium

A
  • Exterior collagen layer.
  • Connected to the deep fascia
  • epi - outside; mysium - muscle
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6
Q

Perimysium

A
  • Surrounds muscle fiber bundles (fascicles).
  • It contains blood vessels and nerve supply to fascicles
  • peri - surround; mysium - muscle
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7
Q

Endomysium

A
  • Surrounds individual muscle cells (muscle fibers)
  • Contains capillaries and nerve fibers contracting muscle cells
  • Contains satellite cells (stem cells) that repair damage
  • endo - internal/inside; mysium - muscle
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8
Q

Skeletal muscle cells are called __________

A

Fibers

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9
Q

Muscles have extensive vascular systems that:

A
  • supply large amounts of oxygen
  • supply nutrients
  • carry away wastes
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10
Q

Skeletal muscles are _________ muscles, controlled by ________ of the central nervous system

A

Voluntary
Nerves

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11
Q

Skeletal Muscle Fibers

A
  • Are very long
  • Develop through fusion of mesodermal cells (myoblasts- embryonic cells))
  • Become very large
  • Contain hundreds of nuclei –multinucleate
  • Unfused cells are satellite cells- assist in repair after injury
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12
Q

The cell membrane of a muscle cell

A

Sarcolemma

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13
Q

sarcoplasm

A

cytoplasm of muscle fiber

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14
Q
  • Transmit action potential – impulses through cell
  • Allow entire muscle fiber to contract simultaneously
  • Have same properties as sarcolemma
    Filled with extracellular fluid
A

Transverse Tubules (T tubules)

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15
Q

Myofibrils

A

1-2um in diameter
* Lengthwise subdivisions within muscle fiber
* Made up of bundles of protein filaments

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16
Q

2 Types of Myofilaments:

A
  • Thin filaments - made of the protein actin
  • Thick filaments - made of the protein myosin
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17
Q

__________ are responsible for muscle contraction

A

Myofilaments

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18
Q
  • A membranous structure surrounding each myofibril
  • Helps transmit action potential to myofibril
  • Similar in structure to smooth endoplasmic reticulum
  • Forms chambers (terminal cisternae) attached to T tubules
A

Sarcoplasmic Reticulum (SR)

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19
Q

________ is formed by 1 T tubule and 2 terminal cisterna

A

Triad

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20
Q

Concentrate Ca2+ (via ion pumps)

A

Cisternae

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21
Q

The contractile units of muscle

A

Sarcomeres

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22
Q

the function of satellite cells

A

repair damage in the endomysium

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23
Q

the function of tendons

A

a flexible tissue that connects the muscles to the bones

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24
Q

the function of ligaments

A

fibrous connective tissue that attaches bone to bone

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25
Q

A striped or striated pattern within myofibrils: alternating dark, thick filaments (A bands) and light, thin filaments (I bands)

A

Muscle Striations

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26
Q
  • the center of the A band
  • at midline of sarcomere
A

M line

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27
Q
  • the centers of the I bands
  • at 2 ends of sarcomere
A

Z lines

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28
Q

The densest, darkest area on a light micrograph

A

Zone of Overlap

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29
Q

The area around the M line

A

H Zone

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30
Q

________ are strands of protein

A

Titin

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31
Q

_______ is caused by interactions of thick and thin filaments

A

Muscle Contraction

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32
Q
  • is 2 twisted rows of globular G actin
  • the active sites on G actin strands bind to myosin
A

F actin

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33
Q

holds F actin strands together

A

Nebulin

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34
Q
  • is a double strand
  • prevents actin-myosin interaction
A

Tropomyosin

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35
Q

a globular protein

A

Troponin

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36
Q
  • Ca2+ binds to receptor on troponin molecule
  • Troponin–tropomyosin complex changes
  • Exposes active site of F actin
A

Initiating Contraction

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37
Q
  • Contain twisted myosin subunits
  • Contain titin strands that recoil after stretching
A

Thick Filament

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38
Q

The Mysosin Molecule

A

Tail:
binds to other myosin molecules
Head:
made of 2 globular protein subunits
reaches the nearest thin filament

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39
Q

During contraction, myosin heads:

A
  • interact with actin filaments, forming cross-bridges
  • pivot, producing motion
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40
Q

__________ is the location of neural stimulation

A

Neuromuscular Junction

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41
Q
  • Releases neurotransmitter (acetylcholine or ACh)
  • Into the synaptic cleft (gap between ______________ and motor end plate)
A

Synaptic Terminal

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42
Q

travels across the synaptic cleft

A

Acetylcholine or ACh

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43
Q

Generated by increase in sodium ions in sarcolemma

A

Action Potential

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44
Q

5 Steps of the Contraction Cycle

A
  1. Exposure of active sites
  2. Formation of cross-bridges
  3. Pivoting of myosin heads
  4. Detachment of cross-bridges
  5. Reactivation of myosin
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45
Q

As sarcomeres shorten, muscle pulls together, producing tension

A

Fiber Shortening

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46
Q

Contraction Duration depends on:

A
  • duration of neural stimulus
  • number of free calcium ions in sarcoplasm
  • availability of ATP
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47
Q
  • Ca2+ concentrations fall
  • Ca2+ detaches from troponin
  • Active sites are recovered by tropomyosin
  • Sarcomeres remain contracted
A

Relaxation

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48
Q

A fixed muscular contraction after death

A

Rigor Mortis

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49
Q

Skeletal muscle fibers _________ as thin filaments slide between thick filaments

A

shorten

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50
Q

____________ in the ____________ triggers contraction

A

Free Ca2+
sarcoplasm

51
Q

it depends on:
the number of pivoting cross-bridges
the fiber’s resting length at the time of stimulation
the frequency of stimulation

A

Tension of a Single Muscle Fiber

52
Q

Normal resting sarcomere length:

A

75% to 130% of optimal length

53
Q

Number of pivoting cross-bridges depends on:

A

amount of overlap between thick and thin fibers

54
Q

Optimum overlap produces greatest amount of tension:

A

too much or too little reduces efficiency

55
Q

Length of twitch depends on type of muscle

A

Tension in a Twitch

56
Q

skeletal muscles that help support your movement

A

Twitch muscles

57
Q

A graph of twitch tension development

58
Q

3 Phases of Twitch

A
  1. Latent period
  2. Contraction phase
  3. Relaxation phase
59
Q

a phase of twitch in which the action potential moves through the sarcolemma

A

Latent period

60
Q

a phase of twitch in which the calcium ions bind and tension builds to peak

A

Contraction phase

61
Q

a phase of twitch in which the Ca2+ levels fall, active sites are covered, and the tension falls to resting levels

A

Relaxation phase

62
Q

A stair-step increase in twitch tension

63
Q

Repeated stimulations immediately after relaxation phase:

A

stimulus frequency < 50/second

64
Q

it refers to the addition of individual muscle fibers contraction to produce a combined wave of force

A

wave summation

65
Q

incomplete tetanus

A

ex: cardiac muscle - to prevent the seizure of the heart

66
Q

complete tetanus

A

ex. skeletal muscle

67
Q

single motor neurons or?

A

efferent neurons

68
Q

are the building blocks of muscle control allowing the precise coordination of movement

A

motor units

69
Q

controled by a single motor neuron

A

motor units in skeletal muscle

70
Q

fine control muscle

A
  • small motor unit -
  • eye muscle: 4 fibers per unit

ex. eyes, fingers

71
Q

gross control muscle:

A
  • large motor unit
  • leg muscle: 2000 fibers per unit

ex. leg

72
Q

smooth motion and increasing tension are produced by slowly increasing the size or number of motor units

A

recruitment (multiple motor unit summation)

73
Q
  • Achieved when all motor units reach tetanus
  • it can be sustained only a very short time
A

Maximum Tension

74
Q
  • Less than maximum tension
  • Allows motor units to rest in rotation
A

Sustained Tension

75
Q

The normal tension and firmness of a muscle at rest

A

Muscle Tone

76
Q

2 Types of Skeletal Muscle Tension

A
  • Isotonic contraction
  • Isometric contraction
77
Q

normal tension and firmness of a muscle at rest
importance: crucial for generating our reflexes

A

muscle tone

78
Q

increase flexibility, gives strength
ex: yoga, poliomyelitis

79
Q

isotonic contraction

A

> resistance - (muscle shortens - concentric contraction
< resistance - (muscle lengthens - eccentric contraction

iso - equal
tonic - tension

80
Q
  • isometric contraction
A

iso: same/equal
metric: measure
- skeletal muscle develops tension but is prevented from changing length

81
Q

concentric contraction

A

greater than (>) resistance, muscle shortens

82
Q

eccentric contraction

A

less than (<) resistance, muscle lengthens

83
Q

limit flexibility

84
Q

After contraction, a muscle fiber returns to resting length by:

A
  • elastic forces
  • opposing muscle contractions
  • gravity
85
Q

The pull of elastic elements (tendons and ligaments)

A

Elastic Forces

86
Q

Reverse the direction of the original motion

A

Opposing Muscle Contractions

87
Q

Can take the place of opposing muscle contraction to return a muscle to its resting state

88
Q

the active energy molecule

A

Adenosine triphosphate (ATP)

89
Q

the storage molecule for excess ATP energy in resting muscle

A

Creatine phosphate (CP)

90
Q

Recharging ATP:

A

Energy recharges ADP to ATP by using the enzyme creatine phosphokinase (CPK)

91
Q

Cells produce ATP in 2 ways:

A
  1. aerobic metabolism
  2. anaerobic glycolysis
92
Q

__________ is the primary energy source of resting muscles

A

Aerobic Metabolism

93
Q

_________ is the primary energy source for peak muscular activity

A

Anaerobic Glycolysis

94
Q

Muscle Metabolism:

A
  1. resting muscle
  2. moderate activity
  3. peak activity
95
Q

When muscles can no longer perform a required activity

A

Muscle Fatigue

96
Q

Results of Muscle Fatigue

A
  1. Depletion of metabolic reserves
  2. Damage to sarcolemma and sarcoplasmic reticulum
  3. Low pH (lactic acid)
  4. Muscle exhaustion and pain
97
Q

The time required after exertion for muscles to return to normal

A

Recovery Period

98
Q

The removal and recycling of lactic acid by the liver

A

Cori Cycle

99
Q

Oxygen Debt

A

After exercise:
* the body needs more oxygen than usual to normalize metabolic activities
* resulting in heavy breathing

100
Q

Skeletal muscles at rest metabolize _________ and store __________

A

fatty acids
glycogen

101
Q

Hormones and Muscle Metabolism:

A
  • Growth hormone
  • Testosterone
  • Thyroid hormones
  • Epinephrine
102
Q

the maximum amount of tension produced

103
Q

the amount of time an activity can be sustained

104
Q

Power and endurance depend on:

A
  • the types of muscle fibers
  • physical conditioning
105
Q

3 Types of Skeletal Muscle Fibers:

A
  1. Fast fibers - Contract very quickly
  2. Slow fibers - Slow to contract, slow to fatigue
  3. Intermediate fibers - Mid-sized
106
Q
  • Have large diameter, large glycogen reserves, few mitochondria
  • Have strong contractions, fatigue quickly
A

Fast fibers

107
Q
  • Have small diameter, more mitochondria
  • Have high oxygen supply
  • Contain myoglobin (red pigment, binds oxygen)
A

Slow fibers

108
Q
  • Have low myoglobin
  • Have more capillaries than fast fiber, slower to fatigue
A

Intermediate fibers

109
Q
  • mostly fast fibers
  • pale (e.g., chicken breast)
A

White muscle

110
Q

mostly slow fibers
dark (e.g., chicken legs)

A

Red muscle

111
Q

Most human muscles:

A
  • mixed fibers
  • pink
112
Q

Muscle growth from heavy training

A

Muscle Hypertrophy

113
Q

Lack of muscle activity

A

Muscle Atrophy

114
Q

What is the difference between aerobic and anaerobic endurance, and their effects on muscular performance?

A
  • Physical Conditioning
  • Improves both power and endurance
115
Q

Anaerobic Endurance:

A
  • Anaerobic activities (e.g., 50-meter dash, weightlifting):
  • use fast fibers
  • fatigue quickly with strenuous activity

Improved by:
- frequent, brief, intensive workouts
hypertrophy

116
Q

Aerobic Endurance

A
  • Aerobic activities (prolonged activity):
  • supported by mitochondria
  • require oxygen and nutrients

Improved by:
- repetitive training (neural responses)
- cardiovascular training

117
Q

Cardiac muscle is ________, found only in the _________

A

striated
heart

118
Q

7 Characteristics of Cardiocytes:

A
  • are small
  • have a single nucleus
  • have short, wide T tubules
  • have no triads
  • have SR with no terminal cisternae
  • are aerobic (high in myoglobin, and mitochondria)
    *have intercalated discs
119
Q

cardiac muscle cells

A

Cardiocytes

120
Q

_________ are specialized contact points between cardiocytes

A

Intercalated Discs

121
Q

4 Functions of Cardiac Tissue:

A
  • Automaticity
  • Variable contraction tension
  • Extended contraction time
  • Prevention of wave summation and tetanic contractions by cell membranes
122
Q

Smooth Muscle

A

Nonstriated tissue

123
Q

8 Characteristics of Smooth Muscle Cells:

A
  1. Long, slender, and spindle shaped
  2. Have a single, central nucleus
  3. Have no T tubules, myofibrils, or sarcomeres
  4. Have no tendons or aponeuroses
  5. Have scattered myosin fibers
  6. Myosin fibers have more heads per thick filament
  7. Have thin filaments attached to dense bodies
  8. Dense bodies transmit contractions from cell to cell
124
Q

Functional Characteristics of Smooth Muscle:

A
  1. Excitation–contraction coupling
  2. Length–tension relationships
  3. Control of contractions
  4. Smooth muscle tone

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