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Anatomy Lecture > Chapter 9 - Muscles > Flashcards

Chapter 9 - Muscles Flashcards

0
Q

Muscular tissue accounts for _____ of total body mass

A

45%

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1
Q

The scientific study of muscles is known as ____

A

Myology

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2
Q

Does most of the work generated by the body

A

Muscles

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3
Q

Functions of muscles

A
  1. Maintain posture and body position
  2. Movement
  3. Heat production
  4. Guard orifices
  5. Support visceral organs
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4
Q

Four properties of muscle tissue

A
  1. Excitability
  2. Contractility
  3. Extensibility
  4. Elasticity
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5
Q

The ability to receive and respond to electrical or chemical stimuli

A

Excitability

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6
Q

The ability to shorten forcibly when stimulated

A

Contractility

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7
Q

The ability to be stretched forcibly when stimulated

A

Extensibility

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8
Q

Ability to return to original shape after being stretched

A

Elasticity

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9
Q

Muscles are ____

A

Organs

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10
Q

Tissue types in muscles

A
  1. Connective
  2. Arteries/Veins
  3. Nerves
  4. Lymphatics
  5. Contractile muscle cells
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11
Q

Seven skeletal muscle characteristics

A
  1. Attaches to bone, skin, or fascia
  2. Striated with light and dark bands
  3. Voluntary control
  4. Long, thin and multi-nucleated fibers
  5. Arranged into packages that attach to and cover the bony skeleton
  6. Contracts rapidly, but tire easily
  7. May exert great force
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12
Q

One muscle cell = ?

A

One fiber

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13
Q

Main portion of a muscle

A

Belly (Gaster)

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14
Q

Muscle structure

A
  • Belly is attached to tendons

- Tendons are attached to bone

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15
Q
  • Dense irregular CT around muscle

- Holds it in place and separates it from other muscles

A

Deep fascia

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16
Q

Loose CT beneathskin, surrounds several muscles

A

Subcutaneous fascia

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17
Q

Skeletal muscle organization

A
  • Many muscle fibers are bundled together into groups called fascicles
  • 10-100 muscles cells (fibers)
  • Several fascicles make up a muscle
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18
Q

Three layers in skeletal muscle CT

A
  1. Epimysium
  2. Perimysium
  3. Endomysium
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19
Q

Surrounds the whole muscle

A

Epimysium

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20
Q

Surrounds fascicles

A

Perimysium

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21
Q

Separates individual muscle fibers (cells)

A

Endomysium

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22
Q

All connective tissue extends beyond the muscle belly to form the _____

A

Tendon

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23
Q

Tendons may form thick flattened sheets called

A

Aponeuroses

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24
Q

Embryonic cells that fuse to form muscle fibers

A

Myoblasts (Thats why they are so long and multinucleate)

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25
Q

Myoblasts that do not fuse become ___

A

Myosatellite cells

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26
Q

Assist in repair of damaged cells

A

Myosatellite cells

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27
Q

Three components to fiber structure

A
  1. Sarcoplasm
  2. Sarcolemma
  3. Transverse (T) tubule
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28
Q

Fiber cytoplasm

A

Sarcoplasm

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29
Q

Plasma membrane of a fiber

A

Sarcolemma

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30
Q

Extensions of the sarcolemma into the sarcoplasm

A

Transverse (T) tubule

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31
Q

Contractile organelles that extend the length of fiber

A

Myofibrils

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32
Q

Myofibrils are surrounded by the ____

A

Sarcoplasmic reticulum

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33
Q

Characteristics of sarcoplasmic reticulum

A
  • Similar to ER

- Contains calcium ions

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34
Q

The functional unit of a myofibril is called a ____

A

Sarcomere

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35
Q

What are sarcomeres made of?

A

Thick and thin filaments

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36
Q

What are thick filaments made of?

A

Myosin

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37
Q

Characteristics of myosin

A
  1. Twisted protein with globular heads
  2. 1.6 um long
  3. 500/thick filament
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38
Q

Two components to thin filaments

A
  1. Actin

2. Regulatory proteins

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39
Q
  • Structural protein

- Coiled “beads”

A

Actin

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40
Q

Allow and prohibit attachment between actin and myosin

A

Regulatory proteins

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41
Q

Two regulatory proteins in the thin filaments

A
  1. Tropomyosin

2. Troponin

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42
Q

Causes the striated appearance of muscle

A

Sarcomere “bands”

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43
Q

Four bands in sarcomere with their meanings

A
  1. A band - entire thick filament
  2. I band - only thin filaments
  3. H band - only thick filaments
  4. Zone of overlap - both filaments
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44
Q

Divide and flank the sarcomere

A

Sarcomere “lines”

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45
Q

Two sarcomere lines

A
  1. Z line

2. M line

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46
Q
  • The end of the sarcomere
  • Made of actinin proteins
  • Anchor thin filaments
A

Z line

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47
Q
  • Middle of the sarcomere

- Stabilize thick filaments

A

M line

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48
Q

Three structural proteins

A
  1. Titin
  2. Nebulin
  3. Actinin
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49
Q
  • Anchors a thick filament to a Z line

- Accounts for elasticity and extensiblity

A

Titin

50
Q
  • Holds F actin together on thin filaments
A

Nebulin

51
Q

Makes up Z line

A

Actinin

52
Q

As the actin slides over the myosin

A
  • Zone of overlap enlarges
  • H bands shrinks
  • I band shrinks
  • A band remains the same
  • The Z line moves closer to the A band
53
Q

Six components to neuromuscular junctions

A
  1. Motor unit
  2. Neuromuscular junction
  3. Synaptic terminal
  4. Motor end plate
  5. Synaptic cleft
  6. Neurotransmitters
54
Q

Neuron and all muscle cells stimulated by the nueron

A

Motor unit

55
Q

Point of contact between the neuron and the muscle

A

Neuromuscular junction

56
Q

End of axon that contacts motor end plate

A

Synaptic terminal

57
Q

Point on muscle fiber that contacts synaptic terminal

A

Motor end plates

58
Q

Gap between two synaptic terminals

A

Synaptic cleft

59
Q

Chemical released into that gap

A

Neurotransmitters

60
Q

When chemicals are released into the gap between the synaptic terminal

A

Acetylcholine (Ach)

61
Q

Events of muscle contraction

A
  1. Ach stored in synaptic vesicles
  2. Impulses reaches end of neuron — ach released
  3. Ach crosses gap and binds to receptors
  4. Impulse travels through motor end plate down T-tubles to SR
  5. Ca2+ ions diffuse out of SR into sarcoplasm
  6. Ca2+ exposes the active site
  7. Myosin then binds to active site
  8. ATP is used and contraction occurs
  9. Contraction continues as long as Ca2+ concentration is high
62
Q

Explain how the muscle moves due to to using ATP

A
  • The myosin head attaches to at binding site on the actin
  • ATP causes the myosin to flex and pull on the actin
  • The thin filaments slide inward
63
Q

Explain the events of muscle relaxation

A
  • Ach decomposed by acetylcholinesterase
  • Ca ions transported back to SR
  • Actin and myosin links broken
  • Cross bridges move back
  • Active site is blocked once again
64
Q

How is tension produced by a muscle determined?

A
  • The frequency of stimulation

- Number of motor units stimulated

65
Q

All fibers in a motor unit fully contract if stimulated

A

All or None Law

66
Q

Steady increase in tension by increasing the number of contracting motor unit

A

Recruitment

67
Q

Muscle never begins to relax, continuous fused contraction

A

Tetanus

68
Q

What is muscle tone?

A
  • Motor units contract randomly

- Tension, but no movement

69
Q

What can muscle tone do?

A
  • Stabilize joints
  • Holds objects in place
  • Maintain posture
70
Q

Constant, exhaustive stimulation increases the number of organelles/proteins in a fiber

A

Hypertrophy

71
Q

What does hypertrophy do?

A 
Increase:
Mitochondria 
Glycolytic enzyme reserves
Myofibrils
Filaments within myofibrils
72
Q

Do muscle fibers reproduce?

A

No you idiot, why would they?

73
Q

Overall enlargement of the muscles is do to what?

A

Hypertrophy

74
Q
  • Lack of constant motor neuron stimulation reduces organelles and proteins
  • Reversible if fiber is not dead
A 
Due to:
Age
Hormones
Lack of use
Nerve damage
75
Q

Three components to muscle attachment

A
  • Origin, insertion, force
76
Q

Attachment site that does not move

A

Origin

77
Q

Attachment site that moves

A

Insertion

78
Q

Tension

A

Force

79
Q

Fascicle arrangement varies based on _____

A

Position of muscles

80
Q

Fascicles parallel to long axis

- Unidirectional force

A

Parallel muscles

81
Q

Example of parallel muscles

A

Biceps brachii

82
Q

Fan shaped muscles

A

Convergent muscles

83
Q

Characteristics of convergent muscles

A
  • Multidirectional force
  • Versatility
  • Generates least amount of force
84
Q

Example of convergent muscle

A

Pectorais major

85
Q

Feather shaped muscles

A

Pennate muscles

86
Q

Characteristics of pennate muscles

A
  • Fascicles oblique to long axis
  • Tendon passes through muscle
  • Greatest force
87
Q

Example of pennate muscles

A

Deltoid

88
Q

Characteristics of circular muscles

A
  • Concentric fascicles around opening

- Contraction decreases lumen diameter

89
Q

Example of circular muscles

A

Orbicularis oculi

90
Q

Rotation around one axis

A

Uniaxial

91
Q

Movements produced on a uniaxial axis

A
  • Rotation: atlantoaxial, pivot joints

- Angular: knee, IP joints

92
Q

Movements occurs along 2 axes

A

Biaxial

93
Q

Angular motions of biaxial movements

A
  • Flexion/extension
  • Abduction/adduction
    Ex: ellipsoidal joint, radiocarpal, metacarpal phalange; carpometacarpal (2-5)
94
Q

Movement on all axes

A

Multiaxial

95
Q

Angular motions of multiaxial

A
  • Same as biaxial
  • Rotation
  • Circumduction
  • Ex: ball and socket
96
Q

Main muscle causing directional force

A

Agonist

97
Q

This can be any muscle of interest

A

Agonist

98
Q

Muscle that contracts to oppose agonist

A

Antagonist

99
Q

Examples of antagonist pairs

A
  • Bicep brachii

- Tricep brachii

100
Q

Muscles that assists/modifies movement

A

Synergist

101
Q

Example of synergists

A
  • Brachialis

- Pronator teres

102
Q

Muscles that stabilizes elements associated with agonist

A

Fixator

103
Q

Example of fixator muscles

A

Deltoid stabilizes glenohumeral joint

104
Q

Lever systems modify what?

A

Movements

105
Q

Levers can change what?

A
  • Magnitude of force
  • Speed
  • Direction
  • Distance of limb movement
106
Q

Components of a lever system (with meanings)

A
  • Lever (L) = skeletal element
  • Effort (E) = applied force (AF)
  • Fulcrum (F) = joint
  • Resistance (R) = body part or object moved
107
Q

Explain the two characteristics of first class levers

A
  • Teeter-totter/ See-saw

- R opposite of E with central F

108
Q

Example of first class levels

A 
E = neckextensors
F = alanto-occipital joint
R = skull
109
Q

Two components to second class levers

A
  • Wheel barrow

- E opposite of F to move R

110
Q

Example of second class lever

A

Plantar extension
E = calf
F = MP joint
R = weight of body

111
Q

Characteristics of third class levers

A
  • Shovel, broom

- E in between F and R

112
Q

Example of third class levers

A

Elbow flexion
E = biceps brachii
F = elbow joint
R = weight distal to joint

113
Q

Seven characteristics of skeletal muscle fibers

A
  • Fast acting; high energy requirements
  • Anaerobic
  • Large diameter
  • Densely packed myofibrils
  • Large glycogen reserves
  • Few mitochondria
  • Rapid, powerful brief contractions
114
Q

Characteristics of slow muscle fibers

A
  • More myoglobin; slower sustained contraction
  • Aerobic
  • Smaller diameter
  • Longer to contract
  • Contract for longer time
115
Q

Characteristics of intermediate fibers

A
  • Attributes of both
  • Similar to fast fibers
  • Greater resistance to fatigue
  • Exercise (or lack of) can change one muscle type to another
116
Q

Seven characteristics of smooth muscle

A
  • Attached to hair follicles in skin
  • In walls of hollow organs and blood vessels
  • Nonstriated
  • Involuntary control
  • Contractions are slow and sustained
  • Spindle shaped
  • Very elastic
117
Q

These muscles contract slowly and are resistant to fatigue

A

Smooth muscles

118
Q

Smooth muscles are stimulated by what?

A
  • Nervous system
  • Hormones
  • Ions
  • Stretching
119
Q

Explain why smooth muscles is a single unit

A
  • Many gap junctions
  • Sheets of spindle-shaped cells
  • Contract together (syncytial contraction )
120
Q

Example of where single unit smooth muscle is

A
  • BV’s
  • Digestive tract
  • Respiratory tract
  • Urinary tract
121
Q

Example of multi-unit smooth muscles

A
  • Walls of large BV’s
  • Uterus
  • Iris of eye
122
Q

Why can smooth muscles be multi-unit?

A
  • No or few gap junctions
  • Separate fibers; contract independently
  • Only contract when stimulated by motor nerve
123
Q

Cardiac muscle characteristics

A
  • Striated in appearance
  • Involuntary control
  • Autorhythmic
  • Network of fibers with intercalated disks at ends
  • Found only in heart

Anatomy Lecture (17 decks)

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