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BMS 150 Midterm 2 > Skeletal Muscle Physiology 1 > Flashcards

Skeletal Muscle Physiology 1 Flashcards

1
Q

our skeletal muscles are composed of ?

A

bundles of fascicles

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2
Q

each fascicle is composed of linearly aligned ?

A

muscle fibers (myofiber)

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3
Q

T or F: Muscle fiber is a single, multi-mucleated, elongated cell

A

true

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4
Q

each muscle fibre is composed of many ?

A

myofibril

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5
Q

myofibrils have many ?

A

sacromere

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6
Q

what is a sacromere?

A

structural units of myofibrils that facilitate contraction and relaxation

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7
Q

what is the epimysium

A

the connective tissue sheath surrounding the whole muscle and extending from the tendons

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8
Q

what is the sheath surrounding each fascicle?

A

perimysium

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9
Q

what is the sheath that surround each individual muscle fiber?

A

endomysium

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10
Q

what is the cell membrane of the muscle cell?

A

sarcolemma

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11
Q

each myofibril composed of many ?

A

myofilaments

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12
Q

what are the contractile proteins of the muscle?

A

actin and myosin

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13
Q

what are the regulatory proteins of the muscle?

A

tropomyosin and troponin

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14
Q

sacromeres consist of interdigitating myofilaments called

A

thin filaments and thick filaments

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15
Q

thin filaments are made of ?

A

actin

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16
Q

thick filaments are made of?

A

myosin

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17
Q

the striated appearance of skeletal muscle is due to ?

A

the overlapping of thick and thin filaments

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18
Q

each sarcomere is bound by the ?

A

Z-disk

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19
Q

thin filament attaches to the

A

Z-disk

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20
Q

at the center of the sarcomere is the ?

A

M-line

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21
Q

thick filaments lie between the

A

thin filaments

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22
Q

what are light bands (I bands)

A

regions of thin filaments that do not overlap with thick filaments

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23
Q

what is at the center of the light bands?

A

the Z-disk

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24
Q

what are dark bands (A bands)

A

the region where the thick and thin filaments do overlap

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25
Q

during muscle contraction, the I band ?, while the A band ?

A
  • shortens
  • does not change in length
26
Q

what is the monomer of Actin?

A

G-actin

27
Q

what is the polymer of actin?

A

F-actin

28
Q

thin filaments are composed of 2 strands of ?

A

F-actin

29
Q

each G-actin monomer has a?

A

binding site for myosin

30
Q

what is the major constituent of the thin filament?

A

F-actin

31
Q

what is the thick filament composed of?

A

myosin

32
Q

myosin head region, has 3 important biochemical features:

A
  • ATPase activity
  • actin-binding region
  • ATP binding region
33
Q

what is the regulatory protein that associates with actin?

A

tropomyosin

34
Q

what are the 3 subunits of troponin?

A
  • troponin C
  • troponin T
  • troponin I
35
Q

which troponin binds to calcium?

A

troponin C

36
Q

which troponin binds to tropomyosin

A

troponin T

37
Q

which tropinin binds to actin and inhibits contraction

A

troponin I

38
Q

how do cross-bridge formation occur

A

when calcium binds to tropinin C, the troponin complex undergoes a conformational change and troponin T “pulls” tropomyosin and troponin I off of the myosin-binding site of G-actin subunits

39
Q

what is the plasma membrane of the muscle fiber called?

A

sarcolemma

40
Q

the sarcolemma contains invaginations called?

A

transverse tubules (aka T-tubules)

41
Q

what allows the action potential to be carried deep into the muscle fiber?

A

transverse tubules

42
Q

what is the sarcoplasmic reticulum

A

a specialized endoplasmic reticulum containing high concentrations of calcium

43
Q

what are the terminal cisternae of the sarcoplasmic reticulum

A

specialized regions that associate with the T-tubules

44
Q

what is the junction between T-tubules and sarcoplasmic reticulum cisterna called?

A

muscle triad

45
Q

a motor nerve axon contacts each muscle fiber near the middle of the fiber, foriming a synapse called the ?

A

neuromuscular junction

46
Q

what is the region of the sarcolemma in closest contact with the presynaptic nerve terminal called?

A

motor end plate

47
Q

what does the motor nerve terminal release?

A

acetylcholine

48
Q

what bind to the nicotinic receptor on the sarcolemma?

A

acetylcholine

49
Q

what happens when the acetylcholine binds to the nicotinic receptor?

A

it activates voltage-gated sodium channels

50
Q

what happens when voltage-gated sodium channels are activated?

A

triggering an action potential that propagates along the sarcolemma

51
Q

the action potential propagates along the surface of the skeletal muscle fiber and penetrate deeper into the muscle fiber via what?

A

T-tubules

52
Q

what is the purpose of T-tubule

A

to “bring” the action potential deep within the very large muscle fibres

53
Q

action potential propage along the T-tubules and activate what? in the sarcolemma

A

L-type Ca2+ channels

54
Q

activation of the L-type Ca2+ channels also triggers mechanical activation of what? on the surface of the SR terminal cisterna within the cell

A

Ryanodine receptors (RYR) which release calcium into the cytosol of the muscle fiber

55
Q

opening of L-type Ca2+ channels and RYR allows what?

A

Ca2+ to flow down its concentration gradient into the cytosol of the muscle fiber

56
Q

what happens to the calcium released by L-tyoe Ca2+ channels and RYR?

A

it bins to troponin C subunit to expose the binding sites for myosin

57
Q

T or F: most of the calcium that activates the skeletal muscle sarcomere is from the SR, NOT the extracellular fluid

A

true

58
Q

what is a motor unit?

A

all the muscle fibers innervated by a single nerve fiber

59
Q

what is a tetany?

A

development of force (tension) in a muscle fiber due to many action potentials

60
Q

what is fused tetany?

A

maximal force development in the muscle fibres of a motor unit

BMS 150 Midterm 2 (16 decks)

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