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2017 physiology > Exam 3 (chapter 12) > Flashcards

Exam 3 (chapter 12) Flashcards

1
Q

Contraction of a muscle is accomplished by thin filaments from opposite sides of each sarcomere _____ _____ together between thick filaments

A

sliding closer

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2
Q

_____: Force exerted on an object by contracting muscle

A

Tension

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3
Q

____=Force exerted on the muiscle by weight of object

A

Load

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4
Q

_____: Mechanical response of a single muscle fiber to a single AP

A

Twitch

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5
Q

Contraction time of a muscle twitch starts at the _____ and ends when the ______ ends

A

Action potential

Impulse

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6
Q

Isotonic contraction is ______ action potentials

A

between

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7
Q

what connects skeletal muscle to bones?

A

tendons

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8
Q

Bundles of muscle fibers

- contain 100s-1000s of muscle cells

A

fascicles

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9
Q

muscle fibers are surrounded by _______________ tissue

A

connective (endomysium)

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10
Q

plasma membrane of a muscle fiber

A

sarcolemma

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11
Q

muscle fibers are ________nucleated

A

multi

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12
Q

Cytoplasm of a muscle fiber

A

sarcoplasm

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13
Q

Microscopic protein filaments that make up muscle cells.

- actin and myosin

A

myofibrils

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14
Q

Thin Myofilaments are primarily

A

Actin

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15
Q

Thick Myofilaments are primarily of

A

Myosin

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16
Q

Organization of muscle fibrils:

A

Myofibril->Myofilaments (Thick+thin)

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17
Q

The smooth ER of a muscle cell

- stores Ca++

A

sarcoplasmic reticulum

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18
Q

muscle fibers contain ___________ mitochondria

A

many (high energy)

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19
Q

System of tubules that provides channels for ion flow throughout the muscle fibers to facilitate the propagation of an action potential.

A

T (transverse) tubules

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20
Q

Transverse tubules (T-tubules) are extensions of the sarcolemma (muscle cell membrane) that penetrate into the centre of skeletal and cardiac muscle cells. T-tubules are highly specialised structures, that form within the first few weeks of life,[1] containing large amounts of specific proteins known as ion channels that allow for electrical impulses (action potentials) travelling along the sarcolemma, to enter rapidly into the cell, to initiate muscle contraction

A

ye

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21
Q

aka terminal cisternae

  • expanded regions of sarcoplasmic reticulum
  • associated with T-tubules
  • involved in the storage and release of Ca2+ in skeletal muscle cells
A

Lateral sacs

22
Q

t tubule + two lateral sacs

A

Triad

23
Q

what gives skeletal and cardiac muscle a striated appearance?

A

Myofibrils

24
Q

Thin filaments

  • contractile protein
  • made of G actin
A

Actin

25
Q

Thick filament

  • actin binding site
  • nucleotide binding site for ATP and ATPase
A

Myosin

26
Q

a globular subunit with an active site for binding myosin head

A

g actin

27
Q

g actin

A

a globular subunit with an active site for binding myosin head

28
Q

A fibrous protein made of a long chain of G actin molecules twisted into a double helix; main protein of the thin myofilament

A

f actin

29
Q

A regulatory protein that covers myosin binding sites along the thin filament (actin), preventing actin and myosin from interacting

A

tropomyosin (rope)

30
Q

A globular protein that associated with tropomyosin as part of the thin filament
- binds Ca2+, causing the conformaiton change in tropomyosin required to expose the myosin-binding sites on actin and initiate muscle contraction

A

Troponin

31
Q

myosin heads are enzymes, what kind are they?

A

ATPase

32
Q

shortening of the sarcomere occurs as myosin heads bind to the exposed sites on actin, forming cross bridges and pulling the actin filament along the thick filament, resulting in contraction

A

Sliding filament model

33
Q

How muscle contractions are turned on and off

A

excitation contraction coupling

34
Q

Explain the process of excitation contraction coupling

A

A motor neuron connects to a muscle at the neuromuscular junction, where a synaptic terminal forms a synaptic cleft with a motor-end plate.

The neurotransmitter acetylcholine diffuses across the synaptic cleft, causing the depolarization of the sarcolemma.

The depolarization of the sarcolemma stimulates the sarcoplasmic reticulum to release Ca2+, which causes the muscle to contract.

35
Q

how muscles generate force

A

crossbridge cycle

36
Q

Cross bridge cycle part _:
reactivation of myosin head: ATP hydrolized to ADP and inorganic phospahte; Energy released during hydrolizes reactivates myosin head returning it to cocked postion

A

4

37
Q

Cross bridge cycle part _:

the power stroke: ADP released and activated myosin head pivotes; Slides thin myofilament toward center of sarcomere

A

2

38
Q

Cross bridge cycle part _:
cross bridge detachment: Link between mysoin head and actin weakens when another ATP ataches to myosin head; Myosin head detaches

A

3

39
Q

Cross bridge cycle part _:
cross bridge formation:Activated myosin head binds to actin forming a cross bridge; Inorganic phospahte released; Bond between myosin and actin becomes stronger

A

1

40
Q

how muscle cells provide ATP to drive the crossbridge cycle

A

muscle cell metabolism

41
Q

shortening of muscle is

A

contraction

42
Q

according to the sliding filament model, do thick or thin filaments shorten?

A

no

43
Q

sliding is due to cyclical ___________ and ______ of cross bridges (crossbridge cycle)

A

formation, breaking

44
Q

cyclical formation of links between actin and myosin, resulting in the sliding of thick filaments toward the middle of the sarcomere

  • myosin head undergoes conformational changes, swiveling back and forth
  • relies on hydrolysis of ATP
A

crossbridge cycle

45
Q

oar paddle

A

crossbridge

46
Q

oar contact with water

A

linking of thick filament to thin filament

47
Q

myosin heads move, propelling thin filament toward center of muscle

A

power stroke (movement of oar propelling boat)

48
Q

oar breaks contact with water

A

thick and thin filaments detach

49
Q

oar moved to new position, cycle starts again

A

myosin head returns to the initial position

50
Q

ATP has bound the myosin to the actin… but ATP can’t be released without another taking its place, so when dead run out of ATP so no muscle relaxation can occur

A

Rigor mortus

51
Q

what are the 5 steps of the cross bridge cycle in skeletal muscle?

A

binding of myosin to actin, power stroke, rigor, unbinding of myosin and actin, cocking of myosin head

2017 physiology (20 decks)

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