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Physiology And Disease > The Molecular Basis of Muscle Contraction > Flashcards

The Molecular Basis of Muscle Contraction Flashcards

1
Q

Sliding filament model of muscle contraction

A

A theory where thick and thin filaments overlap when muscle contracts, with myosin sliding over actin as a result of cross-bridge cycle formation.

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2
Q

Cross-bridge cycle formation

A

The process that allows muscle cells to contract through the interaction between myosin heads and actin filaments.

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3
Q

Actin filaments

A

Thin filaments that slide when activated by ATP during muscle contraction.

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4
Q

Myosin

A

Thick filaments that pull actin filaments towards the center of the sarcomere during muscle contraction.

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5
Q

Sarcoplasmic reticulum (SR)

A

A structure that stores calcium ions and plays a role in excitation-contraction coupling.

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6
Q

Calcium (Ca2+)

A

An ion that binds to troponin complex, triggering muscle contraction by allowing myosin heads to bind to actin.

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7
Q

Tropomyosin

A

A thin filamentous molecule that covers the myosin binding site on actin, preventing interaction between actin and myosin when the muscle is relaxed.

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8
Q

Troponin

A

A complex with four calcium binding sites that changes conformation when occupied by Ca2+, allowing muscle contraction.

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9
Q

Sarcomere

A

The basic structural unit of muscle fibers, defined by two adjacent Z discs.

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10
Q

A band

A

The region of thick filaments in a sarcomere that does not change width during contraction. = overlap of actin and myosin

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11
Q

I band

A

The region of thin filaments in a sarcomere that shortens when the muscle contracts.

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12
Q

Z discs

A

Thin dark thread-like lines that define the boundaries of a sarcomere. Shortens during contraction.

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13
Q

Power stroke

A

The movement of actin towards the center of the sarcomere during the cross-bridge cycle.

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14
Q

ATP hydrolysis

A

The process that energizes the myosin head to form a cross-bridge with actin.

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15
Q

Calmodulin

A

A protein that plays a role in the regulation of smooth muscle contraction.

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16
Q

Twitch

A

A single contraction of a muscle fiber in response to a stimulus.

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17
Q

Summation

A

The process where the force generated by a motor unit may fuse when a second activation occurs before the muscle relaxes.

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18
Q

H zone

A

The region in a sarcomere where only thick filaments are present.

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19
Q

Thin filament

A

Filaments made of actin that interact with thick filaments during muscle contraction.

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20
Q

Thick filament

A

Filaments made of myosin that pull thin filaments during muscle contraction.

21
Q

Muscle relaxation

A

The process where the interaction between actin and myosin is prevented, allowing the muscle to return to its resting state.

22
Q

Frequency of activation

A

The rate at which muscle fibers are stimulated, affecting the tension generated.

23
Q

Fast twitch motor units

A

Motor units that generate quick, powerful contractions but fatigue rapidly.

24
Q

Slow twitch motor units

A

Motor units that generate slower, more sustained contractions and are resistant to fatigue.

25
Q

Calcium binding sites

A

Sites on troponin complex that, when occupied by Ca2+, trigger muscle contraction.

26
Q

Myofilaments

A

Coherent fibers formed from the interaction between thick and thin filaments.

27
Q

Muscle cell activation

A

The process by which a muscle cell is stimulated to contract, involving the binding of calcium to troponin.

28
Q

Cross-bridge

A

Formed between myosin heads and actin filaments.

29
Q

Sarcoplasmic Reticulum (SR)

A

Releases Ca2+ to initiate muscle contraction.

30
Q

Acetylcholine (ACh)

A

Neurotransmitter that stimulates muscle contraction.

31
Q

Excitation-Contraction Coupling

A

Process linking muscle stimulation to contraction.

32
Q

Myosin Light Chain Kinase (MLCK)

A

Phosphorylates myosin for smooth muscle contraction.

33
Q

Power Stroke

A

Myosin pulls actin towards the sarcomere center.

34
Q

Sliding Filament Model

A

Describes how thick and thin filaments interact.

35
Q

Z Discs

A

Define boundaries of a sarcomere.

36
Q

Thick Filaments

A

Composed of myosin, interact with actin.

37
Q

Thin Filaments

A

Composed of actin, interact with myosin.

38
Q

T-tubules

A

Invaginations of sarcolemma for action potential propagation.

39
Q

Phosphate (Pi)

A

Released during cross-bridge formation, strengthens bond.

40
Q

Skeletal Muscle

A

Striated muscle under voluntary control.

41
Q

Smooth Muscle

A

Non-striated muscle under involuntary control.

42
Q

Cross-bridge Cycle

A

Series of steps for muscle contraction.

43
Q

Neurotransmitter Release

A

Initiates muscle cell activation at neuromuscular junction.

44
Q

Action Potential

A

Electrical signal triggering muscle contraction.

45
Q

Intracellular Ca2+ Levels

A

Regulate muscle contraction intensity and duration.

46
Q

Phosphorylation

A

Addition of phosphate group, activates myosin.

47
Q

Calcium Activation

A

Ca2+ binding leading to muscle contraction.

48
Q

Sarcoplasmic Reticulum Function

A

Stores and releases Ca2+ for muscle contraction.

49
Q

Actin-Myosin Interaction

A

The protein-to-protein interaction between myosin and actin results in muscle constraction

Physiology And Disease (10 decks)

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