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AU14 Physiology > EX1; Skeletal Muscle > Flashcards

EX1; Skeletal Muscle Flashcards

1
Q

What is the organization of the skeletal muscle (7)

A 
whole muscle
fascicle
muscle fiber (cell)
myofibril
sarcomere
filament
protein
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2
Q

What is the shape of actin molecules

A

Two intertwined helical chains of actin molecules (like pearls)

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3
Q

These two things are found on the actin chains

A

troponin

tropomyosin

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4
Q

Troponin comprised of what three subunits

A

TnC (calcium)
TnI (inhibits muscle function)
TnT (binds tropomyosin)

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5
Q

Troponin also contains what specific site

A

Ca binding site

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6
Q

A troponin is found every how many actin molecules

A

7

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7
Q

What is the structure of the myosin filament

A

2 pairs light chains per myosin

2 heavy chains

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8
Q

What is the orientation of the cross bridges of the myosin filament

A

opposite for the left and right

heads away from the center, tails toward

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9
Q

This represents the same protein but slightly different amino acid sequence; similar function

A

isoform

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10
Q

True or False

You are born with all your muscle cells, they just undergo isoform changes

A

True

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11
Q

This is the functional unit of the contractile apparatus, which can shorten and generate force

A

sarcomere

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12
Q

What three things compose the sarcomere

A

thick filaments, thin filaments, and Z-lines (or Z disks)

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13
Q

True or False

There is one sarcomere to one muscle cell

A

False; there are many sarcomeres in every muscle cell

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14
Q

This anchors the thin filaments

A

Z line

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15
Q

This large protein extends from Z line to the thick filaments, aiding the thick filaments to remain in the center of the sarcomere

A

titan

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16
Q

This is a thin filament protein; possibly a molecular ruler to determine filament length

A

nebulin

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17
Q

True or False

A major difference between skeletal and cardiac muscle is that cardiac muscle does not contain nebulin

A

True

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18
Q

This is the mechanism by which AP in sarcolemma initiates muscle contraction

A

excitation-contraction coupling

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19
Q

This ion plays a pivotal role in the activation of skeletal muscle

A

calcium

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20
Q

What is the design of the excitation contraction coupling

A

toward achieving a rapid and very large increase in the free calcium ion concentration inside muscle cells

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21
Q

This binds Ca ions in the lateral sacs

A

calsequestrin

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22
Q

Ca is pumped here before it diffuses into the lateral sac

A

fenestrated collar

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23
Q

The lateral sacs and the fenestrated collar are found where

A

in the sarcoplasmic reticulum

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24
Q

Ca ions are released from the lateral sacs of the SR to initiate what

A

contraction

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25
Q

Ca ions re sequestered by the fenestrated collar of the SR to cause what

A

relaxation

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26
Q

What is used to transport Ca in and out of the SR

A

Ca-ATPase pump

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27
Q

This moves deeper into the actin groove upon the introduction of calcium to expose the myosin binding sites on actin

A

tropomyosin

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28
Q

This states that muscles shorten by a relative sliding of thick and thin filaments; the filaments do not change in length

A

sliding filament theory

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29
Q

Using the cross bridge theory; thick and thin filaments are or are not connected at rest

A

they are NOT

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30
Q

These form between the two types of filaments following an increase in free Ca

A

cross-links (cross-bridges)

31
Q

What two things constitute a cross bridge

A

actin and myosin

32
Q

Which one, actin or myosin, regulates the cross bridge cycle

A

myosin

the light chain actin are modulatory

33
Q

What is the first step of the cross bridge theory

A

cross bridge binds to actin

34
Q

Upon the cross bridge binding to actin, what then happens

A

the power stroke; cross bridge moves (z-line decrease) release of ADP and P

35
Q

When ADP and P is released during the movement of the power stroke, what happens to the myosin

A

it undergoes a conformational change

36
Q

What binds to the myosin causing the cross bridge to detach

A

ATP

37
Q

What energizes the cross bridge

A

the hydrolysis of ATP

38
Q

The energized cross bridge then does what

A

bind to actin, and the cycle repeats again and again

39
Q

The amount of force generated is proportional to what

A

the number of attached cross bridges

40
Q

The rate of the cross bridge cycle determines the rate (velocity) of what

A

muscle shortening; different types of myosin go through the cycle at different rates

41
Q

True or False

muscle shortening and force generation are energy-consuming events

A

True

42
Q

The source of energy for force generation and muscle shortening is what

A

ATP

43
Q

Why is there no change in ATP during muscle contraction

A

phosocrestine buffering

44
Q

Where in the sarcomere is the creatine kinase found; of which deals with ATP and phosphocreatine

A

at the M line; right in the center of energy consumption

45
Q

How much ATP is consumed per cross bridge

A

one cross bridge = one ATP

46
Q

What are the consumers of ATP and how much ATP do they consume

A

myosin ATPase; contraction (70)

Ca ATPase; relaxation (30)

47
Q

This is a fundamental property of striated muscle that reflects the arrangement and length of thick and thin filaments

A

length-tension relationship

48
Q

The amount of tension (force) that a muscle can generate when it is activated is dependent upon what

A

its length

49
Q

This states that a muscle can shorten at a higher velocity when moving a lighter load

A

load-velocity (force-velocity) relationship

50
Q

What does the load-velocity relationship show us about the cross bridge cycle

A

the cross bridge cycle to cause shortening since the rate of cycling determines shortening velocity

51
Q

Velocity of skeletal-muscle fiber shortening and lengthening is a function of what

A

load

52
Q

Generally in mammalian muscles, the amount of ten sun generated by a muscle, per unit of cross-sectional area, is fairly consistent, this shows us what

A

the difference in the power generated by different muscles is determined mainly by the speed (velocity) of contraction

53
Q

What is different about the latent period when comparing moving a light, intermediate or heavy load

A

the latent period is longer for heavier loads because you need to build up enough energy to move said load

54
Q

A single muscle is composed of an assembly of this; a single motor neuron and all of the muscle fibers it innervates

A

motor units

55
Q

True or False

most muscle fibers have one NMJ and are innervated by a single motoneuron

A

True

56
Q

True or False

Motoneurons can innervate more than one muscle fiber

A

True

57
Q

How many different muscle fibers can be controlled by a single motor unit

A

it varies from 100 in muscles controlling fine movement and up to 2,000 muscle fibers in large muscles of the leg

58
Q

What three things can each muscle fiber type be distinguished from other types by

A

structural, biochemical, and physiological

59
Q

True or False

The types of fibers comprising a muscle are developed from birth and are unchanging

A

False; they may change during developments, some disease, and in some cases following exercise training

60
Q

What two classifications are used in distinguishing muscle fibers

A

fast or slow

61
Q

Which fiber, fast or slow has smaller neuromuscular junctions

A

slow

62
Q

Which fiber, fast or slow are larger in diameter

A

fast

63
Q

Which fiber, fast or slow contains different sarcomere protein isoforms

A

slow

64
Q

Which fiber, fast or slow are more fatigue resistant

A

slow

65
Q

Which fibers, IIA or IIB are smaller

A

IIA

66
Q

Which fibers, IIA or IIB depends more on an oxidative metabolism

A

IIA

67
Q

Which fibers, IIA or IIB are less fatigable and contract a little slower

A

IIA

68
Q

Which fibers, IIA or IIB depends more on glycolytic metabolism

A

IIB

69
Q

Muscles that are utilized for maintaining posture have a high proportion of what fibers

A

type I

70
Q

Muscles that are utilized to perform tasks rapidly and with a lot of dexterity contain primarily which fibers

A

type II

71
Q

This type II fiber are faster and generate more power but are less efficient

A

IIB

72
Q

Which fibers are most efficient overall (among skeletal fiber types)

A

type I

73
Q

What are 5 systemic disorders are associated with muscle cramps

A

dehydration
metabolic; low sodium, magnesium, ca, glucose, potassium
endocrine; thyroid, adrenal insufficiency
pregnancy
drugs and toxins

74
Q

This is a deficiency or defect in dystrophin; links cytoskeletal (structural) proteins to membrane leading to membrane tears and weakness in skeletal and cardiac muscle

A

muscular dystrophy

AU14 Physiology (24 decks)

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