Muscle Physio Flashcards

1
Q

Skeletal muscle is the predominant site of

A

Thermogenesis

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2
Q

3 types of muscle tissue

A

Smooth
Cardiac
Skeletal

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3
Q

Muscle fibers are surrounded by the

A

Sarcolemma

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4
Q

What is the sarcolemma?

A

Specialized plasma membrane with an outer coat of polysaccharides and collagen

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5
Q

Skeletal muscle is the largest site for (2)

A

Blood glucose storage

Lipid oxidation

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6
Q

Sarcoplasm contains (4)

A

Mitochondria
Ions
Enzymes
Sarcoplasmic reticulum

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7
Q

Where is the main storage site for Ca?

A

Sarcoplasmic reticulum

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8
Q

What is calsequesterin?

A

Binds Ca

Maintains Ca in low energy state while in the SR

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9
Q

Where is calsequesterin located?

A

In the sarcoplasmic reticulum

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10
Q

4 components of myofilaments

A

A band
I band
H band
Z line/disk

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11
Q

A band

A

Overlap thick and thin filaments

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12
Q

What is a thick filament

A

Myosin

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13
Q

What is a thin filament

A

Actin

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14
Q

I band

A

Contains actin filaments

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15
Q

H band

A

Contains myosin

In the light area of the sarcomere

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16
Q

Z line/disk

A

End boundary of the sarcomere

Anchored to actin

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17
Q

Myosin contains

A

2 heavy chains

4 light chains

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18
Q

Myosin head contains

A

ATPase needed for contraction

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19
Q

Actin is made of a double helix of _______ which is made up of _____, _______, and _______

A

F actin
G actin
Troponin
Tropomyosin

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20
Q

Troponin’s job is to

A

Shield myosin binding sites on actin

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21
Q

Tropomyosin is the

A

Binding domain in actin

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22
Q

Troponin I

A

Actin attachment

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23
Q

Troponin T

A

Tropomyosin attachment

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24
Q

Troponin C

A

Ca binding

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25
Q

The motor neuron terminus is ______ and ______

A

Unmyelinated

Branches into the muscle cell

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26
Q

What is the neuromuscular junction?

A

Juncture between the motor neuron and muscle tissue

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27
Q

What can alpha motor neurons do?

A

Convert choline into ACh

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28
Q

How is the ACh signal deactivated?

A

Acetrylcholinesterase degrades ACh

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29
Q

What are endplate potentials (EPP)?

A

Sub-threshold membrane depolarizations

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30
Q

What is the job of T tubules

A

Relays the signal from the sarcolemma deep into the muscle cells

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31
Q

What is DHPR?

A

Voltage gated Ca channels

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32
Q

Where are DHPRs?

A

In the T tubule on clusters of ryanodine receptor Ca channels that are embedded in the SR membrane

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33
Q

What’s RyR?

A

Ryanodine receptor Ca channels

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34
Q

What happens to DHPR as the AP travels down the T tubule?

A

Undergo conformational change that opens a pore in RyR to allow Ca to flow from the SR lumen to the sarcoplasm

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35
Q

Isotonic contractions

A

Forceful

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36
Q

Isometric contractions

A

Non-forceful

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37
Q

Sarcomere shortening and force is generated during an ______ contraction

A

Isotonic

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38
Q

Sarcomere shortening does not occur during an _____ contraction

A

Isometric

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39
Q

How is cross-bridge cycling ended? (2)

A

Decrease Ca concentrations

Decreased sarcoplasmic ATP concentrations

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40
Q

What is the effect of hypercalcemia?

A

Induce hpoexcitability because it increases the membrane potential need to open voltage gated Na channels

41
Q

What is the effect of hypocalcemia?

A

Increase nerve and muscle excitability

42
Q

What is the role of extracellular Ca?

A

Stabilize membrane Na channels in skeletal muscle and neurons

43
Q

What is the main source of ATP?

A

Oxidative metabolism of carbs, FA, and protein

44
Q

What is the function of the SERCA pump?

A

Pump Ca from the sarcoplasm into the SR lumen

45
Q

What is the role of the NCX Exchanger?

A

Leak channel that helps lower Ca concentrations in the sarcoplasm

46
Q

What are 2 ways the muscle can relax and which is the primary one?

A
SERCA pump (main one)
NCX Exchanger
47
Q

What happens if we block the NCX from functioning?

A

Ca would still be elevated in the sarcoplasm

Facilitate contractions

48
Q

Concentric contractions

A

Muscle shortens to displace load

Force generated by muscle overcomes the load

49
Q

Eccentric contractions

A

Resistance against contraction is more than contractile force

50
Q

When is the propensity for muscle damage higher? (Concentric or eccentric contraction)

A

Eccentric

51
Q

Passive tension

A

Resistance of muscle tissue to stretch due to anatomical properties

52
Q

Active tension

A

Change in tension during muscle contraction

53
Q

When does active tension peak?

A

During early phase of isotonic muscle contractions

54
Q

When is the greatest force generated? Why?

A

During initial phase of muscle contraction from L0

Optimal overlap of myosin and actin

55
Q

What is a muscle twitch and when does it occur?

A

Single rapid muscle contraction responding to a single AP

Before a muscle contraction

56
Q

What is muscle tetany and when does it occur?

A

Maximum strength of contraction

When rapid successive twitches fuse

57
Q

What is the orderly recruitment principle?

A

Smaller motor units (fatigue resistant) are activated first and then the larger motor units (powerful, fatiguable) are activated

58
Q

Type 1 fibers

A

Slow twitch
Red bc of the vasculature
Sustain activity

59
Q

Type 2 fibers

A

Fast twitch

Brief periods of time

60
Q

A single motor unit can innervate

A

Only ONE type of muscle fiber as it branches in the muscle

61
Q

IGF1 and GH promote

A

Myofibrillar protein synthesis

62
Q

What are satellite cells

A

Precursors that provide extra nuclei for growth and repair after an injury

63
Q

What does myostatin do?

A

Block cell cycle progression of satellite cells

64
Q

What happens if there’s a loss of function in myostatin?

A

Increase muscle mass

65
Q

What is the effect of IGF1 on satellite cells?

A

Proliferation

66
Q

Resistance training results in

A

Hypertrophy of mainly type 2 fibers

67
Q

High volume resistance training improves (3):

A

Insulin sensitivity
Lipid profiles
Hypertension

68
Q

Hypertrophy

A

Increase diameter of muscle fibers

69
Q

Angiogenesis

A

Synthesis of vascular tissue

70
Q

Exercise induces an up Regulation in (4):

A

Mitochondrial number and function
ATP and phosphocreatine content
Enhanced levels of intramuscular glycogen stores
Increase intramuscular triglyceride levels

71
Q

SERCA expression is controlled by

A

Thyroid hormone

72
Q

Thyroid hormone can upregulate ________ but not increase ______

A

Rate of contraction and relaxation

Contractile force

73
Q

What is sarcopenia?

A

Loss of muscle mass that’s associated with age

74
Q

When is peak muscle mass obtained?

A

20-30s

75
Q

6 effects of glucocorticoids in skeletal muscle:

A

Dec. proteogenesis
Dec. rate of AA transport
Inhibit IGF1
Stim. Proteolytic signaling (UB-proteosome)
Stim. Myostatin production
Inhib. Myogenin expression (TF needed for satellite cell differentiation)

76
Q

Myokines can modulate

A

Muscle hypertrophy and myogenesis

77
Q

What is a motor unit?

A

One motor neuron and the muscle fiber(s) it innervate

78
Q

When are type 1 motor units recruited?

A

During sustained muscle activity (aerobic)

79
Q

Alpha motor neurons mediate

A

Voluntary contractile responses of skeletal muscle

80
Q

What is the main function of muscle spindles?

A

Monitor/allow continuation of muscle contraction

81
Q

Muscle spindles have ________ designed to _______ in _____ and _______

A

Sensory receptors
Detect changes
Muscle length
Rate of change of length

82
Q

What does GTO stand for? Where are they located? And what’s they job?

A

Golgi Tendon Organs
Musculotendon junction
Relay information to CNS about muscle tension

83
Q

What do GTOs serve as?

A

Early warning system when tension has suddenly increased

84
Q

Why are GTOs important?

A

Prevent against muscle tear by having Type In afferents synapse with stimulatory/inhibitory interneurons

85
Q

What is fatigue?

A

Decrease contractile force due to an increased stimulation frequency or duration

86
Q

Where is smooth muscle usually located?

A

Wall surrounding hollow organs and vessels

87
Q

Contraction and relaxation of VSM is controlled by (3)

A

SNS
Hormones
Metabolites

88
Q

Actin filaments in smooth muscle is attached to

A

Dense bodies, which may be attached to the cell membrane

89
Q

Dense bodies do not contain (5)

A
Sarcomere
Z disks
T tubules
Motor end plate
Troponin
90
Q

How does smooth muscle contract? How’s does the muscle cell appear?

A

Sliding filament mechanism

Crinkled

91
Q

4 extracellular sources of Ca for smooth muscle

A

Voltage gated Ca channels
Voltage independent Ca channels
Ca induced Ca release
IP3 mediated signal transduction

92
Q

What is calmodulin?

A

Ca sensor in smooth muscle that binds to Ca to activate myosin light chain kinase

93
Q

In smooth muscle, how does myosin become phosphorylated and what does that mean?

A

Activation of myosin light chain kinase

Phosphorylated myosin has high affinity for actin

94
Q

Smooth muscle contraction uses _____ metabolism and can perform ________ duration contractions using ______ metabolic energy

A

Oxidative
Long
Very little

95
Q

How can smooth muscle can shorten?

A

Contract on itself in multiple dimensions

Doesn’t alter the overlap btwn myosin and actin (50-75% shortening)

96
Q

Why can smooth muscle stretch more than skeletal, while maintaining active tension?

A

Loose arrangement of actin and myosin in smooth muscle

97
Q

Higher tension ensures

A

Sufficient perfusion pressures are maintained

98
Q

Filling an arterioles with blood causes ______ because ______

A

Profound elevation in pressure

Tension does NOT drop