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Physiology Exam 2 > Skeletal Muscle and Reflexes > Flashcards

Skeletal Muscle and Reflexes Flashcards

1
Q

functional unit of cardiac & skeletal muscle

A

Sarcomere

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2
Q

What type/size is the lower motor neuron that goes to muscle?

A

A-alpha

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3
Q

What is the anatomical origin of the muscle from largest to smallest?

A 
A.Whole Muscle
B.Muscle Fascicles
C.Muscle Fibers (Cells)
D.Myofibrils
E.Myofilaments (Thick and Thin) arranged in Sarcomeres
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4
Q

Alternating ____ bands and _____ bands creates the striated appearance in skeletal and cardiac muscle.

A

A-bands and I-Bands

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5
Q

Which band is the dark band?

A

A-band

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6
Q

Which band is the light band?

A

I-band

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7
Q

Sarcomere structure: Entire Length of Thick Filaments

A

A-Band (Dark)

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8
Q

Sarcomere structure: Includes only Thin Filaments

A

I-Band (Light)

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9
Q

Sarcomere structure: Only Thick Filaments

A

H-Zone

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10
Q

Sarcomere structure: Thin Filaments Anchored Here

A

Z-Line

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11
Q

Sarcomere structure: Link the Central Regions of Thick Filaments

A

M-Line

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12
Q

Which band does not change in size in contraction?

A

A band

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13
Q

In contraction, the zone of overlap _____

A

increases

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14
Q

In contraction, I-Band _____

A

Decreases

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15
Q

In contraction, H-Zone _____

A

Decreases

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16
Q

The thin filament is composed of ____

A

actin, tropomyosin, and troponin

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17
Q

____ are the active site which binds myosin)

A

G-actin molecules,

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18
Q

______ binds actin, tropomyosin, and calcium).

A

troponin

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19
Q

_____ filament has multiple cross-bridges where the “heads” can bind to the G-actin molecule; also functions as an ATPase enzyme.

A

myosin (thick)

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20
Q

_____ Protein connects thin filaments to glycoproteins in sarcolemma

A

Dystrophin protein

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21
Q

Which form of muscular dystrophy is associated with decreased dystrophin?

A

Beckers

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22
Q

_____ are invaginations of muscle that allow the signal to get all the way into the middle of the sarcomere

A

T-tubules

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23
Q

The alpha motor neuron releases ____ which binds to a _____ on the muscle fiber

A

ACh; nicotinic ACh receptor (NM)

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24
Q

______ inhibits the release of ACH at the neuromuscular junction; can be used in dentistry (Bruxism, Sialorrhea, Masseteric Hypertrophy, etc.)

A

Botulinum toxin A

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25
Q

What are the 3 phases of muscle twitch?

A

Latent, contraction, and relaxation

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26
Q

In resting muscle, _____ prevents a strong bond between the myosin head and G-actin molecules

A

tropomyosin

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27
Q

When ______ binds to cytosolic Ca++, tropomyosin is pulled away from the myosin binding site, and allows for the power stroke

A

troponin

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28
Q

When troponin binds to cytosolic Ca++, _____ is pulled away from the myosin binding site, and allows for the power stroke

A

tropomyosin

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29
Q

When troponin binds to cytosolic Ca++, tropomyosin is pulled away from the myosin binding site, and allows for the ____

A

power stroke

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30
Q

Calcium is released from the ______ in muscle

A

Sarcoplasmic Reticulum

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31
Q

modified ER that sequesters Ca2+

A

Sarcoplasmic Reticulum (SR):

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32
Q

invaginations of sarcolemma

A

Transverse (T)-Tubules:

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33
Q

Portion of SR that contact T-tubules

A

Terminal Cisternae:

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34
Q

The AP travels down the membrane, down T-tubules, & activates voltage-sensitive ______ receptors on the T-tubules.

A

dihydropyridine (DHP)

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35
Q

dihydropyridine (DHP) receptors turn open calcium channels called _____ receptors on the SR.

A

(ryanodine receptors)

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36
Q

Calcium goes from SR to the ______.

A

sarcoplasm

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37
Q

(connection between actin and myosin)

A

cross-bridge

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38
Q

_____ binding to the myosin head breaks the cross-bridge

A

ATP

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39
Q

Energy released from _____ by the myosin head provides energy for cocking the myosin head

A

ATP hydrolysis

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40
Q

Release of inorganic _____ from the myosin head provides energy for the POWER STROKE

A

phosphate

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41
Q

(myosin head pulling actin towards the center of the sarcomere). This shortens the sarcomere.

A

POWER STROKE

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42
Q

Muscle cells only have enough ATP for about ____ twitch

A

8 twitches

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43
Q

Both _____ and _____ Metabolism produce ATP for muscle fibers.

A

Aerobic and Anaerobic metabolism

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44
Q

How many ATP are made from glycolytic fibers?

A

2 atp

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45
Q

How many ATP are made from oxidative fibers?

A

32-36

46
Q

Besides metabolism, what is the other mechanism of ATP production for muscles

A

Phosphocreatine

47
Q

Measurement of ______ levels in the blood is done to determine if damage to muscle tissue (skeletal and cardiac) has occurred (ex. heart attack or muscular dystrophy).

A

Creatine Kinase (CK)

48
Q

_____ muscles:1.have decreased tension generation, 2.take longer to contract 3.relax more slowly and may not completely relax.

A

Fatigued

49
Q

Theories for _____ include: Decreased ACH, Blockage of blood flow, increase in pH and lactic acid, increase in Potassium, Increased metabolic byproducts, and Depleted glycogen

A

fatigue:

50
Q

Both ____ and ____ must be present for cross-bridge cycling.

A

Calcium and ATP

51
Q

____ state: myosin and actin are tightly bound

A

Rigor State:

52
Q

For relaxation of skeletal muscle, The _____ neuron must stop firing and Cytosolic (intracellular) ____ concentrations must decrease

A

alpha motor neuron; calcium

53
Q

_____ on SR remove calcium from cytosol

A

Calcium ATPases

54
Q

For relaxation to occur, ____ must be removed, but ___ must be present to release myosin from actin

A

Calcium; ATP

55
Q

In rigor mortis, the rigor state is maintained due to lack of ____

A

ATP

56
Q

Which type of muscle fiber is slow and oxidative; red, slow fatigue and slow myosin ATPase activity; moderate glycolytic capacity, high oxidative capacity

A

Type 1

57
Q

Which type of muscle fiber is Fast and oxidative and glycolytic; red, fast resistant fatigue and fast myosin ATPase activity; high glycolytic capacity, moderate oxidative capacity

A

Type IIa

58
Q

Which type of muscle fiber is Fast and glycolytic; white, fast fatigue and fast myosin ATPase activity; high glycolytic capacity, low oxidative capacity

A

Type IIb

59
Q

Increase in size of muscle

A

Hypertrophy

60
Q

Decrease in size of muscle

A

Atrophy

61
Q

Atrophy due to an increase in age

A

Sarcopenia

62
Q

thickness of the jaw muscles _____ significantly with age

A

decreases

63
Q

The fibre-type composition of the jaw muscles also changes with age. In the jaw-closing muscles of elderly subjects, the proportion of pure type I fibres ______, while the proportion of pure type II fibres and that of hybrid fibres _____

A

decreases; increase

64
Q

a ____ is the alpha motor neuron and the muscle fibers it innervates

A

motor unit

65
Q

a motor unit is the _____ neuron and the muscle fibers it innervates

A

alpha motor neuron

66
Q

What size of motor units are recruited first?

A

Small motor units

67
Q

Smallest motor units control _____ fibers

A

fewer

68
Q

An increase in the number of motor units activated increases the _____ produced by contraction of a muscle

A

total tension

69
Q

An increase in the number of motor units activated increases the total tension produced by contraction of a muscle—_____ SUMMATION

A

SPATIAL summation

70
Q

_____ motor units (X) are composed of slow-twitch oxidative fibers. They have the lowest threshold for firing and are recruited first.

A

Small motor units

71
Q

____ motor units (Z) are composed of fast-twitch glycolytic fibers. They have the highest threshold and are recruited last

A

Larger motor units

72
Q

T/F: Motor units in jaw muscles are restricted to specific areas of the jaw muscles, which permits differential control of separate muscle portions.

A

True

73
Q

____ contraction Force produced is less than the load; no movement.

A

ISOMETRIC CONTRACTION.

74
Q

______ contraction Force produced is great enough to move a load

A

ISOTONIC CONTRACTION.

75
Q

The force of contraction increases until the ____ contraction becomes an ____ contraction—NOT always possible!

A

isometric; isotonic

76
Q

the amount of load and the force the muscle generates determines the ____ of contraction.

A

type

77
Q

In a ____ contraction, the muscle has not shortened; sarcomeres shorten, generating force, but elastic elements stretch, allowing muscle length to remain the same

A

Isometric contraction

78
Q

In a ____ contraction, sarcomeres shorten more but because elastic elements are already stretched the entire muscle must shorten

A

Isotonic contraction

79
Q

Increase total ____ of muscle contraction by (1) increasing the frequency of fiber activation and/or (2) increasing the number of muscle fibers contracting

A

force

80
Q

An increase in the frequency of α motor neuron stimulation will increase the amount of ____ produced.

A

tension

81
Q

The tension produced in response to each action potential will __ if the muscle has not yet completely relaxed

A

sum

82
Q

_____ is where there is the best degree of overlap between the thick and thin filaments; at this point, there is an increased number of crossbridges that can form

A

Optimal length

83
Q

At the optimal length the greatest number of actin/myosin cross-bridges can form, which results to _____ production

A

maximal tension production

84
Q

____ is reduced if the muscle is not stretched enough or if it stretched too much

A

Tension

85
Q

The ____ of contraction (distance moved/time) depends on the load a fiber is contracting against.

A

velocity

86
Q

The greater the load, the ____ the speed of contraction.

A

SLOWER

87
Q

Skeletal muscle fibers/cells that produce the contraction.

A

Extrafusal Fibers

88
Q

Efferent neuron that releases ACh and causes contraction of the extrafusal fiber (skeletal muscle).

A

Alpha Motor Neuron:

89
Q

Small structure within the extrafusal fibers that contains Intrafusal Fibers that have sensory nerve endings wrapped around them that are sensitive to CHANGES IN MUSCLE LENGTH.

A

Muscle spindle

90
Q

Efferent neuron that causes contraction of intrafusal fibers so they mimic what the EF fibers are doing.

A

Gamma Motor Neuron:

91
Q

____ fibers that have sensory nerve endings wrapped around them that are sensitive to CHANGES IN MUSCLE LENGTH

A

Intrafusal Fibers

92
Q

Jaw closers have a lot of muscle _____

A

Spindles

93
Q

When the muscle _____, the sensory fibers of the muscle spindle are squeezed.

A

stretches

94
Q

If the _____ fibers did not contract, the sensory fibers would not be able to sense a further change in muscle length since they would be slack.

A

intrafusal fibers

95
Q

The Effect of Muscle Spindle Activation is _____

A

Contraction

96
Q

T/F: Anytime the alpha motor neuron is activated, the gamma motor neuron is also activated.

A

True

97
Q

Mechanosensitive receptors found at the junction of tendons and muscle. Sensitive to a change in FORCE.

A

Golgi Tendon Organs:

98
Q

The Golgi Tendon Organ Reflex is a _____ reflex.

A

protective

99
Q

mastication is a cyclical movement with develops early in life. It is controlled by the _______ of the brainstem, which when stimulated, elicits rhythmic, coordinated activation and inactivation of jaw-closers and jaw-openers.

A

Central Pattern Generator (CPG)

100
Q

_____ are important modifiers of force.

A

Reflexes

101
Q

Input from higher cortical regions can regulate the CPG frequency via the ______ Pathway

A

Corticobulbar pathway

102
Q

Jaw closer muscles have a lot of muscle ____

A

Muscle spindles

103
Q

Jaw openers have ____ in low densities

A

Tendon organs

104
Q

Pain inhibits the _____ neuron of jaw closing muscles such as when you bite down on your tongue, a metal spoon, with your incisors–Jaw opens

A

alpha motor neuron

105
Q

Strong tap to the chin _____ the jaw closers–The jaw closers respond by contraction so the jaw closes

A

stretches

106
Q

____ starts chewing by activating jaw closing muscles

A

CPG

107
Q

____ fibers in muscle spindle are still contracting and stretching the muscle spindle so this signals further contraction of jaw closing muscles

A

Intrafusal fibers

108
Q

______ decrease the contraction in situations where a lot of force is needed to crack something with the jaw

A

Muscle spindles

109
Q

Powerful ____ contractions stimulate both jaw closing and opening muscles. The jaw openers keep the jaw from snapping shut.

A

isometric contracions

110
Q

When you jog or run, force is applied to the mandible.–With each step, there is a down movement of the mandible in relation to the head.–This movement stretches the ______ which causes a reflex contraction of the jaw closing muscles.

A

muscle spindle

Physiology Exam 2 (6 decks)

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