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Physiology for Pharmacy > Lecture 5: Skeletal Muscle > Flashcards

Lecture 5: Skeletal Muscle Flashcards

1
Q

skeletal muscle converts ___energy to __ energy

A

electrical; mechanical

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2
Q

the process of converting electrical energy to mechanical energy is called __

A

excitation-contraction coupling

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3
Q

an individual muscle cell is called a

A

muscle fiber

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4
Q

t/f the movement of skeletal muscle is under conscious control

A

true

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5
Q

skeletal muscle is striated and multinucleate (t/f)

A

true

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6
Q

myofibrils are the ___ elements

A

contractile

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7
Q

t/f myofibrils run the entire length of of a muscle

A

true

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8
Q

myofibrils contain a regular repeated pattern of ___

A

protein filaments

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9
Q

protein filaments interact with each other in an ___ pattern

A

interdigitating

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10
Q

what are the 3 zones/bands in a myofibril?

A

I band, H zone, A band

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11
Q

what happens to thick and thin filaments during muscle contraction?

A

they slide against us

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12
Q

t/f filaments change shape when they slide over each other

A

false

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13
Q

how does the A band change during muscle contraction?

A

doesn’t change

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14
Q

how does the I band change during muscle contraction?

A

gets shorter

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15
Q

how does the H band change during muscle contraction?

A

gets shorter until it almost disappears

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16
Q

thick protein filaments are made of ___

A

myosin

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17
Q

a myosin filament consists of 2 ___ chains and 2 ___ chains

A

heavy; light

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18
Q

what are the 2 binding sites on a myosin head?

A

atp and actin binding sites

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19
Q

myosin heads have ___ activity

A

atpase

20
Q

what is the energy source for filament movement?

A

atp hydrolysis at myosin head

21
Q

thin protein filaments are made of __ , ___ and __

A

actin, tropomyosin, and troponin

22
Q

actin is made of ___ that are strung together to make __

A

g actin. f actin

23
Q

troponin are ___ proteins

A

globular

24
Q

tropomyosin are __ proteins

A

filamentous

25
Q

explain the steps of the powerstroke

A
  1. myosin head hydrolyses ATP and becomes energized and cocked
  2. the myosin binds to the actin, forming a crossbridge
  3. the myosin cross bridge pivots, puling the thin filament past the thick filament toward the centre of the sarcomere
  4. atp binds to myosin head and head detaches from actin
26
Q

calcium is the __ for muscle contraction

A

trigger

27
Q

explain the role of calcium in muscle contraction

A

ca binds to troponin, which causes tropomyosin to move and reveal the actin binding sites so myosin can bind

28
Q

the sarcoplasmic reticulum has a high concentration of __

A

calcium ions

29
Q

the T-tubule network is an extension of the ___

A

cell membrane

30
Q

what allows an action potential to penetrate into a muscle fibre?

A

t-tubule

31
Q

the t-tubule comes in close contact with ___

A

sarcoplasmic reticulum

32
Q

the t-tubule network is filled with ___

A

extracellular fluid

33
Q

what is the purpose of the T tubule network?

A

allow action potential into muscle fibre to stimulate the release of ca from the sarcoplasmic reticulum

34
Q

t/f dihydropyridine receptors are functional ca channels

A

false

35
Q

t/f ryanodine receptors are functional ca channels

A

true

36
Q

what is the function of the dihydropyridine receptors?

A

detect action potentials and activate ryanidine receptors

37
Q

t/f calcium atpase is constantly pumping calcium in by using atp

A

true

38
Q

what happens when ryanidine receptors are activated?

A

they allow ca to be released from the sarcoplasm reticulum

39
Q

list the 9 steps in EC coupling

A
  1. ach release from nerve
  2. ach induced endplate potential leading to muscle ap
  3. acetylcholinesterase destroys ach
  4. ap causes ca to be released from sr
  5. ca binds to troponin
  6. cross bridge cycling ; contraction
  7. ca reuptake by SR
  8. tropomyosin prevents cross bridge formation
  9. relaxation
40
Q

after an action potential there is a brief ___ period before actual contraction that is caused by ___

A

latent; sliding filaments taking up slack

41
Q

what causes a muscle twitch?

A

single action potential

42
Q

t/f a twitch is the smallest single unit muscle contraction

A

true

43
Q

the number of cross bridges formed is proportional to the amount of ___ generated

A

tension

44
Q

___ is when max tension is reached and all cross bridges are formed

A

fused tetanus

45
Q

unfunded tetanus occurs when:

A

multiple action potentials sequentially (wave summation)

46
Q

why is there less muscle tension when a muscle is overstretched?

A

less overlap of thick and thin to make cross bridges required for tension

47
Q

why is there less muscle tension when a muscle is under stretched?

A

too much overlap, causing thin filaments to overlap with each other instead and preventing cross bridge formation

Physiology for Pharmacy (39 decks)

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