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Kinesiology 3800 > Ch. 1/11 > Flashcards

Ch. 1/11 Flashcards

1
Q

Anatomy of skeletal muscles

A

Muscle fibers
Myofibrils

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2
Q

3 types of muscle tissues

A

Skeletal muscle: voluntary, skeleton

Smooth muscle: involuntary, hollow organs

Cardiac muscle: involuntary, heart

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3
Q

Review: which muscle tissue is voluntary?

A

Skeletal

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4
Q

TF: Skeletal muscle is entirely surrounded by endomysium

A

False
Epimysium

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5
Q

TF: The fascicles within skeletal muscle is surrounded by perimysium

A

True

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6
Q

SM: Consists of individual muscle cells (muscle fibers)

A

Fascicles

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7
Q

SM: Muscle fiber is surrounded by …
-consists of myofibrils divided into…

A

Endomysium
Sarcomeres

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8
Q

MF: Plasmalemma
Fuses with …
Conducts … …
Maintains … . … …

A

Tendon
Action potential
PH, transports nutrients

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9
Q

MF: Sarcoplasm: … Of muscle cell

A

Cytoplasm

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10
Q

MF: Unique features within sarcoplasm

A

Glycogen storage
Myoglobin

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11
Q

MF: Transverse tubules
Extension of …
Carries .. deep into …

A

Plasmalemma
Action potential ➡️ muscle fiber

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12
Q

MF: Stores Calcium

A

Sarcoplasmic reticulum (SR)

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13
Q

How many myofibrils per muscle fiber?

A

Hundreds to thousands

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14
Q

MS: Basic contractile element of skeletal muscle

A

Sarcomere

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15
Q

Sarcomere: Striped appearance/striations (4)

A

– A-bands: dark/blue stripes
– I-bands: light/pink stripes
– H-zone: middle of A-band
– M-line: middle of H-zone

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16
Q

Sarcomere: common boundary structure

A

A-disk

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17
Q

Sarcomere: Thin protein filament that shows up lighter under 🔬 (red)

A

Actin

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18
Q

Sarcomere: 3 proteins within Actin and their functions

A

– Actin: contains myosin-binding site
– Tropomyosin: covers active site at rest
– Troponin: anchored to actin, moves tropomyosin

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19
Q

TF: A-band contains only actin filaments

A

False
I-band

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20
Q

Actin filaments are anchored at …

A

Z-disk

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21
Q

Sarcomere: Thick filaments that show up darker under 🔬 (blue)

A

Myosin

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22
Q

TF: H-zone contains only myosin filaments

A

True

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23
Q

What band contains both protein filaments

A

A-band

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24
Q

Myosin’s globular heads protrude … from thick filaments and will interact w/… for contraction

A

360°
Actin filaments

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25
Q

Function of Titian

A

Stabilizes sarcomere
Centers myosin
Prevents stretching

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26
Q

Titin extends from … to …

A

Z-disk to M-band

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27
Q

Muscle fiber contraction starts with …

A

Nervous system

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28
Q

MFC: innervates muscle fibers and is the motor unit

A

α-Motor neurons

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29
Q

MFC: More operating motor units =

A

More contractile force

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30
Q

Events of Excitation-Contraction Coupling (6) ⭐️

A
  1. Action potential (AP) starts in brain
  2. AP arrives at axon terminal, releases acetylcholine (ACh)
  3. ACh crosses synapse, binds to ACh receptors on plasmalemma
  4. AP travels down plasmalemma, T-tubules
  5. Triggers Ca2+ release from sarcoplasmic reticulum (SR)
  6. Ca2+ enables actin-myosin contraction
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31
Q

Action potential arrives at ST from . … & causes mass release of Ca into sarcoplasm

A

T Tubule

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32
Q

TF: SR sensitive to chemical charge

A

False
Electrical

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33
Q

Ca2+ binds to … on thin filament to move …

A

Troponin
Tropomyosin

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34
Q

Cross-bridge

A

Myosin binds to actin,
allowing a contraction to occur

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35
Q

Sliding Filament theory

A

Myosin and actin filaments sliding past each other

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36
Q

SFT: When relaxed, myofilaments are stable

A

False
They overlap a little

37
Q

SLT: Action where myosin head pulls actin towards Sarcomere center

A

Power stroke

38
Q

TF: In actin myosin contraction, Sarcomeres, myofibrils, muscle fiber all lengthen

A

False
Shorten

39
Q

SFT: After power stroke ends
– Myosin .. from active site
– Myosin head rotates … original position
– Myosin attaches to another active site farther .

A

Detaches
Back to
Down

40
Q

SLT: Power stroke continues until:
Z-disk reaches … filaments
Or
AP stops, Ca get … … SR

A

Myosin
Pumped back into

41
Q

What band does not change?

A

A-band

42
Q

What important molecule/energy is involved in muscle contractions?

A

ATP

43
Q

Function of ATP (2)

A

Binds to myosin head
Allows to release from actin filaments

44
Q

What causes Rigor Mortis?

A

Lack of ATP production.
Cross bridges aren’t able to
detach and this causes
stiffness

45
Q

When AP ends and electrical stimulation of SR stops

A

Muscle relaxation

46
Q

TF: When muscle is relaxed, Ca is pumped out of SR

A

False
Pumped back into SR

47
Q

Review: During muscle contraction, which one(s) shorten

A

H zone
I band

48
Q

What prevents actin-myosin cross bridging?

A

Troponin and tropomyosin

49
Q

Small (10-100 g) piece of muscle removed
Frozen, sliced, examined under microscope

A

Muscle biposy

50
Q

Muscle Fiber Types:
-Slow form of myosin ATPase
-Peak tension in 110ms (slow twitch)
- ~50% of fibers in avg muscle

A

Type I

51
Q

MF Type:
-Fast form of myosin ATPase
– Peak tension in 50 ms (fast twitch)
– Type IIa (~25% of fibers in an average muscle)
– Type IIx (~25% of fibers in an average muscle)

A

Type II

52
Q

T1F: Efficiently produces ATP for … of fat & carbohydrates

A

Oxidation

53
Q

T1F: Recruited most often during …

A

low-intensity
– aerobic exercise (e.g., marathon running)
– daily activities (walking)
– posture

54
Q

T2F: Produces ATP through

A

Anaerobic pathways

55
Q

Which muscle fiber has high aerobic endurance?

A

Type I Fibers

56
Q

T2F: Type that involves more force and is more easily fatigued
*Used for short-high intensity events

A

Type IIa fiber

57
Q

T2F: Type seldom used for everyday activities
*Short, explosive activites

A

Type IIx

58
Q

Fast myosin ATPase =
Slower myosin ATPase =

A

Fast contraction cycling
Slower contraction cycling

59
Q

Which type of fiber has a more developed SR?

A

Type II fibers

60
Q

Motor units between Type I & Type II

A

Type I motor unit:
smaller neuron, <300 fibers
Type II motor unit:
larger neuron, >300 fibers

61
Q

Peak power of fibers from greatest to smallest

A

Type IIx > type IIa > type I

62
Q

Most influential in determining percentage

A

Genetic factors

63
Q

TF: Arm and leg ratios are similar in one person

A

True

64
Q

TF: Type I predominates in power athletes.
Type II predominates in endurance athletes

A

False
Switch athletes

65
Q

TF: Soleus is type II in everyone

A

False
Type I

66
Q

Other predictors of athletic success

A

– Cardiovascular function
– Motivation
– Training habits
– Muscle size

67
Q

When a motor unit is recruited,
ALL of its fibers are activated

A

Motor unit recruitment

68
Q

MFR: Method for altering force production

A

– Less force: fewer or smaller motor units (type I)
– More force: more or larger motor units (type II)

69
Q

Recruitment Order of fibers (size principle)

A

– First: Smallest (type I) motor units
– Next: Midsized (type IIa) motor units
– Last: Largest (type IIx) motor units

70
Q

order of recruitment
of motor units directly related to size of α-motor neuron

A

Principle of orderly recruitment
(size principle)

71
Q

OR: Smaller motor u it’s are recruited first as … threshold

A

Low

72
Q

OR: Higher threshold Motor units are recruited based on..

A

Increasing demand of activity

73
Q

Types of dynamic muscle contraction

A

Concentric
Eccentric

74
Q

MC:
• Muscle shortens while
producing force
• Sarcomere shortens,
filaments slide toward center

A

Concentric contraction

75
Q

MC:

• Muscle lengthens while
producing force
• Cross-bridges form but
sarcomere lengthens

A

Eccentric contraction

76
Q

MC: Muscle produces force but does not change length

A

Static (isometric) contraction

77
Q

Factors for amount of force developed (NT,S,FS,MS,SC)

A
  1. Number and type of motor units activated
  2. Size of the muscle
  3. Frequency of stimulation of each motor unit
  4. Muscle fiber and sarcomere length
  5. Speed of contraction
78
Q

NT:
• Type I motor units = .. fibers = .. cross-bridges =
.. force
• Type II motor units = .. fibers = .. cross-bridges =
.. force

A

Less
More

79
Q

MS:

• Large muscles = more fibers = more cross-bridges =
more force
• Smaller muscles = less fibers = less cross-bridges = less
force

A
80
Q

FS: Contractile response to SINGLE electrical stimulus

A

Twitch

81
Q

FS: CONSECUTIVE STIMULI for greater force

A

Summation

82
Q

FS: CONTINUED stimulation resulting in peak force

A

Tetanus

83
Q

LT: Fibers have … length for force production

A

Optimal

84
Q

LT: Optimal sarcomere length =
– Maximizes cross-bridge interaction

A

Optimal overlap of actin/myosin

85
Q

Optimal sarcomere length =
– Maximizes cross-bridge interaction

A

Optimal overlap of actin/myosin

86
Q

LT: Too short or too stretched =

A

Little or no force develops

87
Q

Ability to develop force
also depends on speed
of contraction

A

Speed-Force relationship

88
Q

SF: maximal force
development decreases at
higher speeds

A

Concentric

89
Q

SF: maximal force
development increases at
higher speeds

A

Eccentric

Kinesiology 3800 (10 decks)

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