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Anatomy > Muscles > Flashcards

Muscles Flashcards

1
Q

What percent body mass does muscle tissue make up?

A

30 - 40%

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2
Q

What is myology?

A

Study of the muscles

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3
Q

What are the 3 types of muscle?

A
  1. Skeletal
  2. Cardiac
  3. Smooth
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4
Q

What kind of muscle attaches to the bone or skin?

A

Skeletal muscle

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5
Q

What kind of muscle constitutes the bulk of the heart wall?

A

Cardiac muscle

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6
Q

What kind of muscle is found in the walls of hollow organs?

A

Smooth muscle

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7
Q

What are the longest muscle cells called?

A

Fibers

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8
Q 
What type of muscle?
• Attached to bones
• Longest muscle cells : FIBERS
• Striated
• Voluntary : consciously controlled
• Multi-nucleated: multiple nuclei/fiber
A

Skeletal muscles

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9
Q 
What kind of muscle?
• Only found in the heart walls
• Striated
• Involuntary: you can NOT control your
heartbeat consciously
• Uni-nucleated and branched
• Intercalated discs join cardiac cells together (gap junctions)
A

Cardiac muscle

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10
Q 
What kind of muscle?
• Found lining walls of hollow organs
• Elongated fusiform cells : FIBERS
• Involuntary: you can NOT control
smooth muscle consciously
• Non-striated
• Uni-nucleated
A

Smooth muscle

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11
Q

What are the four functions of muscle?

A
  1. Producing movement
  2. Maintaining posture
  3. Storing and moving substances within the body
  4. Generating heat
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12
Q

What are the four properties of muscle?

A
  1. Electrical excitability
  2. Contractility
  3. Extensibility
  4. Elasticity
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13
Q

Which property of muscle?
• Ability to receive and respond to a stimulus
• Causes changes in resting membrane potential in the muscle cell
• Respond via an electrical impulse (action potential) passing along the muscle cell

A

Electrical excitability

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14
Q

Which property of muscle?

• Ability to shorten/contract forcibly when stimulated by an action potential to generate tension/force pulling

A

Contractility

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15
Q

Which property of muscle?
• Ability to stretch without being damaged
• Smooth muscle has the most extensibility

A

Extensibility

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16
Q

Which property of muscle?

• Ability to recoil and resume its normal resting length after stretching

A

Elasticity

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17
Q

What surround fibers and whole muscles?

A

Connective tissues

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18
Q

Connective tissue that surrounds

muscles, groups of muscles, blood vessels, nerves, organs

A

Fascia

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19
Q

composed of loose connective tissue (areolar and adipose) which separates the muscles from the skin.
• Serves as a passageway for nerves and vasculature

A

Superficial Fascia

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20
Q

dense connective tissue that groups muscles together into compartments and also surrounds individual muscles

A

Deep (investing) fascia

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21
Q

What is endomysium?

A

areolar CT around fibers

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22
Q

What is perimysium?

A

Dense irregular CT around fascicles

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23
Q

What is epimysium?

A

Dense irregular CT around entire muscle

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24
Q

An artery vein and nerve

• Enter and exit same spot

A

Neuromuscular bundle

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25
Q

Each nerve contains both what?

A

Motor neurons and Sensory neurons

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26
Q

Somatic motor neurons travel from _____ to _______ _______

A

CNS, motor fibers

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27
Q

Axon terminals form the what?

A

Neuromuscular junctions

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28
Q

What is a motor unit?

A

neuron and all the fibers it supplies

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29
Q

What is a muscle direct attachment?

A

muscle directly attaches to bone via the CT layer that is extremely short

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30
Q

What is a muscle indirect attachment?

A

Muscle CT extends as either a tendon (ropelike) or an aponeurosis (sheet-like) that attaches to bone

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31
Q

Where do muscles originate and insert?

A
  • Usually a bone
  • Tendon/ligament
  • Skin
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32
Q

What is a fixed immoveable point of

attachment?

A

Origin

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33
Q

What is an insertion?

A

Moveable bone

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34
Q

What happens when muscles contract?

A

The insertion moves towards the origin allowing for specific actions to occur.

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35
Q

What determines power production and range of motion of the muscle?

A

Fascicle arrangement

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36
Q

Which arrangement is two long axis, tendon at each end?

A

Parallel

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37
Q

Which arrangement is fat in the middle, tapered ends into tendons?

A

Fusiform

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38
Q

Which arrangement is concentric rings?

A

Circular

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39
Q

Which arrangement radiates out from a single tendon to broad attachment?

A

Triangular

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40
Q

Which arrangement is feather like, fibers insert obliquely on the tendon

A

Pennate

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41
Q

What are the 3 types of pennate arrangement?

A
  • Unipennate: obliquely from 1 side of the tendon
  • Bipennate: obliquely on both sides of a central tendon
  • Multipennate: obliquely between multiple tendons
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42
Q

Which of the following is not a
function of muscle?
a. Produce movement
b. Maintain body posture
c. Store and move substances throughout the body
d. Generate heat
e. All of the above are functions of muscle

A

e. All of the above are functions of muscle

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43
Q

Extensibility is:
a. Ability to receive and respond to a stimulus
b. Ability to shorten/contract forcibly when stimulated by an action
potential
c. Ability to stretch without being damaged
d. Ability to recoil and resume its normal resting length after
stretching

A

c. Ability to stretch without being damaged

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44
Q 
Which of the following is a loose
connective tissue that surrounds
muscle fibers? 
a. Epimysium
b. Perimysium
c. Endomysium
A

c. Endomysium

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45
Q

Myoblasts in the embryo fuse

together to form the ______

A

Myocyte

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46
Q

Growth after birth occurs through

_______ of the muscle fiber

A

hypertrophy

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47
Q

What is the sarcolemma of muscle fibers?

A

The plasma membrane

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48
Q

What is the cytoplasm of the muscle fibers?

A

Sarcoplasm

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49
Q

What are transverse tubules?

A

Invaginations of sarcolemma; fast even conduction of APs?

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50
Q

What is sarcoplasmic reticulum?

A

Smooth ER

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51
Q

What are myofibrils?

A

Contractile elements of the fibers

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52
Q

• Conduct impulses that travel from a
nerve to the sarcolemma towards the
muscle fibers
• Ensures that each myofibril contracts at the same time

A

Transverse tubules

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53
Q

What is the sarcoplasmic reticulum?

A

Membranous fluid filled sacs similar to

smooth ER that encircles each myofibril

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54
Q

• Stores calcium (Ca2+) ions
• releases on demand when muscle is
stimulated to contract
• 1 T-tubule + 2 terminal cisternae = TRIAD

A

Sarcoplasmic reticulum

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55
Q

• Rod-like contractile elements
running parallel to the length of
the fiber

A

Myofibrils

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56
Q 
• Contain sarcomeres
• Contractile structural and
functional unit of fiber
• Made up of myofilaments
• Thick and thin filaments
A

Myofibrils

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57
Q

Each myoFIBRIL is composed of

smaller contractile proteins called?

A

myoFILAMENTS

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58
Q

What are the two types of myofilaments?

A
  • Thin (actin) filaments

* Thick (myosin) filaments

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59
Q

From Filaments to muscle put in order.

A

Myofilaments < Myofibrils < Muscle Fibers (myocyte) < Fascicles < Muscles

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60
Q
  • Double stranded fibrous protein
  • G-actin – globular heads contain binding sites for myosin; polymerise to form Factin
  • F-actin – Double stranded fibrous protein
A

Thin Actin Filament

61
Q 
• ~300 proteins/filament
• Each protein contains:
• 1 tail
• 2 heads
• Bind to G actin to form cross
bridges during contraction
• Contain ATP binding sites –
contraction cannot occur without
ATP
A

Thick Myosin Filaments

62
Q

What structural protein anchors thick filaments to the Z disc and M line
• Spring-like that aids in muscle recoil
• Stabilizes thick filaments

A

Titin (connectin)

63
Q

What structural protein forms the M line

• Binds adjacent thick filaments

A

Myomesin

64
Q

What structural protein links myofilament proteins to proteins of the sarcolemma?

A

Dystrophin

65
Q

What structural protein helps maintain alignment of the thin filaments in the sarcomere?

A

Nebulin

66
Q

What structural protein binds actin to titin?

A

Alpha-actinin

67
Q

What genetic disorder is characterized by progressive muscle degeneration and weakness?

A

Muscular Dystrophy

68
Q

What is one of the most common forms of muscular dystrophy and is caused by recessive mutations in the dystrophin gene on X chromosome?

A

Duchenne Muscular Dystrophy (DMD)

69
Q

What is caused by mutations in the dystrophin gene?

• Individuals with BMD share similar signs and symptoms but with later onset and more varied time course

A

• Becker Muscular Dystrophy (BMD)

70
Q

What regulatory protein covers myosin binding site in relaxed muscle and moves out of the way for contraction?

A

Tropomyosin

71
Q 
What regulatory protein keeps tropomyosin covering myosin
binding site?
• Calcium causes a conformational change
• Moves tropomyosin
• Myosin binding site exposed
A

Troponin

72
Q

What are sarcomeres?

A

Smallest functional contractile units.

73
Q

What is the area between 2 Z-discs

A

Sarcomere

74
Q

What are A bands?

A

Thick filaments

75
Q

What are I bands?

A

Thin filaments

76
Q

What are Z discs?

A

Where thin filaments are anchored

77
Q

What are H zones?

A

Center of A band only thick

78
Q

What is the M line?

A

Center of H where thick filaments

join.

79
Q

What is the Sliding Filament Theory?

A

When muscle contract thick and thin
filaments slide past one another
causing sarcomere to shorten.

80
Q

What happens in the Sliding Filament Theory?

A
  • The width of A band does not change
  • The H zone disappears
  • The I bands shorten
  • The Z discs move closer together
  • The sarcomere shortens
  • HI goes bye
81
Q

Keep Ca⁺⁺ from getting out until needed

A

Voltage-gated Ca⁺⁺ channels

82
Q
  • On terminal cistern

* Dump Ca⁺⁺ into sarcoplasm from cistern

A

Ca⁺⁺ release channels

83
Q

Pump Ca⁺⁺ into terminal cistern from

sarcoplasm

A

Ca⁺⁺ ATPase pumps

84
Q 
Which of the following stores
calcium? 
a. T-tubules
b. Terminal cisternae
c. Calmodulin
d. Troponin C
e. Sarcolemma
A

d. Troponin C

85
Q 
During sarcomere shortening, which
of the following would get smaller? 
a. Z disc
b. A band
c. M line
d. I band
e. Actin
A

d. I band

86
Q

Which protein is spring-like to help with muscle recoil and is anchored to the Z disc and M line?

a. Titin
b. Myomesin
c. Dystrophin
d. Nebulin
e. Alpha-actinin

A

a. Titin

87
Q

What are neurons that travel from

the CNS to the muscle fibers?

A

Somatic motor neurons

88
Q

Where do neuron cell bodies reside?

A

In the brain OR spinal cord (ventral horn)

89
Q

What do Axons do?

A
  • Axons travel via the motor nerve to the muscle they serve
  • Axon divides as it enters the muscle
  • Each axon gives off axon terminals that form the Neuromuscular Junction
90
Q

What are small motor units?

A
  • fine motor control

* Muscles of fingers

91
Q

What are large motor units?

A
  • less precise (gross) motor control

* Biceps brachii

92
Q

Junctions between axons and muscle fibers are called?

A

Neuromuscular Junctions

93
Q

What neuromuscular junctions contain vesicles?

A

Pre-synaptic

94
Q

What neuromuscular junctions contain receptors?

A

Post-synaptic

95
Q

What does the synaptic cleft contain?

A

Contains acetylcholinesterase that breaks down ACh.

96
Q 
• Contains synaptic vesicles
(exocytosis)
• Contain neurotransmitter
Acetlycholine (Ach)
• Excitatory chemical that stimulates
the post-synaptic cell to change
membrane potential
A

Presynaptic Neuron Terminal

97
Q

• Contains folds in the sarcolemma to
increase surface area where it meets a
synaptic end bulb = motor end plate
• Contains ACh receptors

A

Post-Synaptic Muscle Fiber

98
Q

What is contraction?

A

The generation of force

99
Q

• Shortening of the muscle fibers
• Occurs when the tension of the crossbridge between the thin and thick
filaments overcomes the force
opposing contraction

A

Muscle contraction

100
Q

Cross-bridges release and the
thin/thick filaments return to normal
length

A

Muscle Relaxation

101
Q

Propagation of action

potential along sarcolemma

A

Excitation

102
Q

Excitation-Contraction Coupling

A
  • Nerve impulse triggers ACh release from pre-synaptic cell into synaptic cleft
  • ACh binds receptors on sarcolemma
  • Muscle fiber gets excited
  • Action potential travels along sarcolemma (transverse tubules)
  • Reaches voltage-gated Ca++ channels causing conformational change
  • Allows Ca++ release channels to open
  • Ca++ floods the sarcoplasm
  • Conformational change in troponin
  • Moves tropomyosin, exposing myosin binding sites
  • Contraction cycle begins
103
Q

Excitation-Contraction Coupling

A
  • Continues if ATP and Ca⁺⁺ levels sufficient
  • Z discs drawn closer
  • Sarcomere shortens
  • Pulls adjacent sarcomeres in myofibril
  • Myofibrils shorten myocyte
  • Myocyte pulls on endomysium
  • Fascicles pull on perimysium
  • Muscles pull on endomysium
  • Tendons pull on bone (skin)
  • Movement
104
Q

Excitation-Contraction Coupling

A
  • Excitation ends/action potential no longer propagating
  • Ca++ voltage-gated channels plug Ca++ release channels
  • Ca++ ATPase pumps pump Ca++ into cisterns
  • Calsequrestrin binds to Ca++ to increase storage
  • Ca++ in sarcoplasm rapidly decreases
  • Troponin changes
  • Tropomyosin to cover myosin binding sites
  • Muscle relaxation
105
Q

Contraction Overview

A

• An action potential travels down a motor neuron and stimulates….
• ACh release from the pre-synaptic terminal
• ACh binding to ACh receptors on muscle causing influx of Na+ ions
• Action potential generated and propagated down the sarcolemma to the TRIAD
• Sacroplasmic reticulum releases Ca2+ ions
• Ca2+ and ATP together cause the cross-bridge cycle:
• Myosin heads attach to actin, bend and release actin several times shortening
the sarcomere..
• Sarcomeres shorten
• Muscle fibers shorten
• Whole muscle shortens

106
Q

When someone dies, the body becomes “stiff”

A

Rigor Mortis

107
Q
  • Produces botulinum toxin
  • Blocks release of acetylcholine
  • No acetylcholine
  • No action potential in myocyte
  • No contraction
  • Paralysis
  • Most cases of botulism occur from improper canning
  • Honey in infants
  • Used cosmetically for prevention of wrinkles
  • Used clinically for spasticity
A

Clostridium Botulinum

108
Q

Results in overstimulation and

excessive muscle contraction.

A

Clostridium Tetani

109
Q 
• Spastic paralysis caused by toxin
produced by Clostridium tetanus
• Prevents release of inhibitory
neurotransmitters GABA and
glycine in spinal cord
A

Clostridium Tetani

110
Q

Acetycholine is released from the:

a. Pre-synaptic terminal
b. Post-synaptic terminal
c. Terminal cisternae
d. Synaptic cleft
e. Dendrite

A

b. Pre-synaptic terminal

111
Q

Which of the following best
describes a motor unit?
a. A muscle and all the neurons that supply it
b. A muscle fiber and all the neurons that supply it
c. A motor neuron and the single muscle fiber it supplies
d. A motor neuron and all the muscle fibers it supplies
e. A motor neuron and the blood vessels that supply a muscle

A

d. A motor neuron and all the muscle fibers it supplies

112
Q

Which of the following is the correct sequence of events for muscle contractions?
a. Muscle cell action potential, neurotransmitter release, ATP-driven power stroke, calcium ion release from SR, sliding of myofilaments
b. Neurotransmitter release, muscle cell action potential, motor neuron
action potential, release of calcium ions from SR, sliding of myofilaments,
ATP-driven power stroke
c. Motor neuron action potential, neurotransmitter release, muscle cell
action potential, release of calcium ions from SR, ATP-driven power
stroke, sliding of myofilaments
d. Neurotransmitter release, motor neuron action potential, muscle cell
action potential, release of calcium ions from SR, ATP-driven power stroke

A

?

113
Q

What is required for contraction, pumping Ca⁺⁺ out of sarcoplasm and
into cisterns?

A

ATP

114
Q

What are the 3 ways of producing ATP?

A
  1. Creatine phosphate – storage for excess ATP
  2. Anaerobic glycolysis – Insufficient O2 levels
  3. Aerobic respiration – Sufficient O2 levels
115
Q
  • At rest myocyte produce excess ATP
  • Creatine kinase moves 1 phosphate from excess ATP to creatine
  • Creatine phosphate (storage at rest)
  • During contraction creatine kinase removes phosphate from creatine phosphate
  • ADP ATP
  • Faster than making ATP
  • Short lived storage (15s)
  • Sprinting, explosive movements, etc
A

Creatine Phosphate

116
Q 
• Glucose catabolism
• Does not require O2
• Utilize glycogen or glucose
• Occurs in sarcoplasm
• Breaks 1 glucose into 2 pyruvic acid
and 2 ATP
• If sufficient O2 – pyruvic acid enters
mitochondria for aerobic respiration
• If insufficient O2 – pyruvic acid goes
through anaeorobic respiration
A

Glycolysis

117
Q 
• O2 is present
• Pyruvic acid is sent to mitochondria
• Goes through Krebs cycle/electron
transport chain
• Makes 30 to 32 ATP
• Provides long term energy source
• 2 minutes to hours
A

Aerobic Respiration

118
Q 
• If insufficient O₂: pyruvic acid
converted into lactic acid
• Lactic acid converted into glucose in
liver / used by heart
• If rate of lactic acid production
exceeds rate of conversion → build
up of lactic acid
• Increasing acidity of blood / muscle
• 2 minutes of activity
A

Anaerobic Respiration

119
Q 
What type of contraction?
• A contracting muscle does not shorten
• Ex. if muscle load > muscle tension
• OR if load is not moved
• Ex. trying to pick up a car
A

Isometric Contractions

120
Q

What type of contraction?

A
  • Muscle tension > muscle load
  • Load is moved
  • Ex. picking up a textbook
121
Q

What gives the muscles tone?

A

Small number of motor units involutarily activated for small degree of contraction to give muscle tone.

122
Q

What is hypotonia?

A

Decrease in muscle tone

123
Q

What is flaccid paralysis?

A

Loss of muscle tone, atrophy of muscles.

124
Q

What is hypertonia?

A

Increased muscle tone leading

to excessive muscle contraction or rigidity.

125
Q

What is muscle atrophy?

A

Wasting of muscles

126
Q

What are two types of atrophy?

A
  1. Disuse

2. Denervation

127
Q

What type of atrophy occurs when muscles are not used?

A

Disuse

128
Q

What type of atrophy occurs when nerve supply to a muscle/s is cut?

A

Denervation

129
Q

Growth of muscle fibers due to increased myofibrils

A

Hypertrophy

130
Q

Occurs due to an increase in
myofibrils with increased
myofilaments NOT FIBERS

A

Hypertrophy

131
Q 
• Myoblasts that do not fuse to
form single muscle fiber
• \_\_\_\_\_\_\_\_ \_\_\_\_\_\_ remain with
skeletal muscle tissue and assist
in repair of muscles
A

Satellite cells

132
Q

What does an agonist muscle do?

A

Produces a specific movement

133
Q

What does an antagonist muscle do?

A

Opposes a movement

134
Q

What is a synergist?

A

Helps with a movement

135
Q

What stabilizes a joint?

A

Fixators

136
Q
  • Drugs that mimic the effects of testosterone

* Taken to increase protein production, especially in the muscles

A

Anabolic Steroids

137
Q

What are some adverse side effects of steroids?

A
  • Left ventricular hypertrophy
  • Liver damage
  • Gynecomastia
  • Testicular atrophy
  • Increased body hair
  • Acne
  • “Roid rage”
138
Q 
The antagonist muscle for the
quadriceps femoris would be: 
a. Triceps brachii
b. Hamstrings
c. Sartorius
d. Iliopsoas
A

b. Hamstrings

139
Q

Which of the following molecules found in skeletal muscle cells binds oxygen that can later be used during aerobic metabolism to help generate ATP?

a. Creatine
b. Creatine phosphate
c. Myoglobin
d. Titin
e. Glycogen

A

c. Myoglobin

140
Q

When oxygen is plentiful inside a skeletal muscle cell, what happens to the pyruvic acid that is formed during glycolysis?

a. It is converted into lactic acid
b. It diffuses into mitochondria to be broken down to generate ATP
c. It diffuses out of the cell and into the bloodstream
d. It is used to convert creatine into creatine phosphate
e. It is converted into glycogen

A

a. It is converted into lactic acid

141
Q

Muscle growth comes from what?

a. Increased division and production of myofibers
b. Increased production of myofibrils
c. Hypertrophy of actin filaments
d. Hypertrophy of myosin filaments

A

b. Increased production of myofibrils

142
Q
  • Individual muscle cells arranged in thick bundles in the heart wall
  • Branched
  • Shorter and thicker than skeletal muscle fibers
A

Cardiac Muscle

143
Q

What is cardiac muscle joined by?

A

Intercalated discs

144
Q 
• Uni-nucleated fusiform shaped cell
• Diffuse junctions instead of NMJ
• Controlled by the autonomic nervous system
(instead of a motor neuron) - involuntary;
• NO SARCOMERES
• Have actin and myosin
• Dense bodies act as z-discs
• Calmodulin replaces troponin
A

Smooth muscle

145
Q

Innervating nerve fibers have

numerous bulb-like swellings called?

A

varicosities

146
Q

What are the 2 smooth muscle layers?

A 
1. Longitudinal Layer
• Parallel direction to the length of the
organ
2. Circular Layer
• Perpendicular direction to the length
of the organ
147
Q

Explain smooth muscle contractions.

A
  • Exhibit slow synchronized contractions
  • Resistant to fatigue
  • Smooth muscle contraction is similar to skeletal muscle:
  • Rise in intracellular Ca2+ triggers contraction (extracellular)
  • Actin and myosin interact
  • Requires ATP (much less than skeletal)
148
Q 
Which of the following is false
regarding smooth muscle? 
a. It is uninucleated
b. It is not-striated
c. It is involuntary
d. It is made of long cylindrical muscle fibers
e. None of the above
A

d. It is made of long cylindrical muscle fibers

149
Q

This structure is unique to cardiac muscle and allows individual cells to be firmly attached to each other and allow the action potential to spread rapidly through the muscle, so contractions are smooth and coordinated.

a. Desmosomes
b. Gap junctions
c. Intercalated discs
d. Z discs
e. Sarcomeres

A

c. Intercalated discs

Anatomy (18 decks)

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