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AU14 Physiology > EX1; Skeletal Muscle > Flashcards

EX1; Skeletal Muscle Flashcards

(74 cards)

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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
Ca ions re sequestered by the fenestrated collar of the SR to cause what
relaxation
26
What is used to transport Ca in and out of the SR
Ca-ATPase pump
27
This moves deeper into the actin groove upon the introduction of calcium to expose the myosin binding sites on actin
tropomyosin
28
This states that muscles shorten by a relative sliding of thick and thin filaments; the filaments do not change in length
sliding filament theory
29
Using the cross bridge theory; thick and thin filaments are or are not connected at rest
they are NOT
30
These form between the two types of filaments following an increase in free Ca
cross-links (cross-bridges)
31
What two things constitute a cross bridge
actin and myosin
32
Which one, actin or myosin, regulates the cross bridge cycle
myosin | the light chain actin are modulatory
33
What is the first step of the cross bridge theory
cross bridge binds to actin
34
Upon the cross bridge binding to actin, what then happens
the power stroke; cross bridge moves (z-line decrease) release of ADP and P
35
When ADP and P is released during the movement of the power stroke, what happens to the myosin
it undergoes a conformational change
36
What binds to the myosin causing the cross bridge to detach
ATP
37
What energizes the cross bridge
the hydrolysis of ATP
38
The energized cross bridge then does what
bind to actin, and the cycle repeats again and again
39
The amount of force generated is proportional to what
the number of attached cross bridges
40
The rate of the cross bridge cycle determines the rate (velocity) of what
muscle shortening; different types of myosin go through the cycle at different rates
41
True or False | muscle shortening and force generation are energy-consuming events
True
42
The source of energy for force generation and muscle shortening is what
ATP
43
Why is there no change in ATP during muscle contraction
phosocrestine buffering
44
Where in the sarcomere is the creatine kinase found; of which deals with ATP and phosphocreatine
at the M line; right in the center of energy consumption
45
How much ATP is consumed per cross bridge
one cross bridge = one ATP
46
What are the consumers of ATP and how much ATP do they consume
myosin ATPase; contraction (70) | Ca ATPase; relaxation (30)
47
This is a fundamental property of striated muscle that reflects the arrangement and length of thick and thin filaments
length-tension relationship
48
The amount of tension (force) that a muscle can generate when it is activated is dependent upon what
its length
49
This states that a muscle can shorten at a higher velocity when moving a lighter load
load-velocity (force-velocity) relationship
50
What does the load-velocity relationship show us about the cross bridge cycle
the cross bridge cycle to cause shortening since the rate of cycling determines shortening velocity
51
Velocity of skeletal-muscle fiber shortening and lengthening is a function of what
load
52
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
the difference in the power generated by different muscles is determined mainly by the speed (velocity) of contraction
53
What is different about the latent period when comparing moving a light, intermediate or heavy load
the latent period is longer for heavier loads because you need to build up enough energy to move said load
54
A single muscle is composed of an assembly of this; a single motor neuron and all of the muscle fibers it innervates
motor units
55
True or False | most muscle fibers have one NMJ and are innervated by a single motoneuron
True
56
True or False | Motoneurons can innervate more than one muscle fiber
True
57
How many different muscle fibers can be controlled by a single motor unit
it varies from 100 in muscles controlling fine movement and up to 2,000 muscle fibers in large muscles of the leg
58
What three things can each muscle fiber type be distinguished from other types by
structural, biochemical, and physiological
59
True or False | The types of fibers comprising a muscle are developed from birth and are unchanging
False; they may change during developments, some disease, and in some cases following exercise training
60
What two classifications are used in distinguishing muscle fibers
fast or slow
61
Which fiber, fast or slow has smaller neuromuscular junctions
slow
62
Which fiber, fast or slow are larger in diameter
fast
63
Which fiber, fast or slow contains different sarcomere protein isoforms
slow
64
Which fiber, fast or slow are more fatigue resistant
slow
65
Which fibers, IIA or IIB are smaller
IIA
66
Which fibers, IIA or IIB depends more on an oxidative metabolism
IIA
67
Which fibers, IIA or IIB are less fatigable and contract a little slower
IIA
68
Which fibers, IIA or IIB depends more on glycolytic metabolism
IIB
69
Muscles that are utilized for maintaining posture have a high proportion of what fibers
type I
70
Muscles that are utilized to perform tasks rapidly and with a lot of dexterity contain primarily which fibers
type II
71
This type II fiber are faster and generate more power but are less efficient
IIB
72
Which fibers are most efficient overall (among skeletal fiber types)
type I
73
What are 5 systemic disorders are associated with muscle cramps
dehydration metabolic; low sodium, magnesium, ca, glucose, potassium endocrine; thyroid, adrenal insufficiency pregnancy drugs and toxins
74
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
muscular dystrophy

AU14 Physiology (24 decks)

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