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Flashcards in Muscular System Deck (69)
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30

Troponin

Calcium complex that modifies the position of tropomyosin

31

First step of Muscle Fiber Contraction

Nerve impulses (action potential) travels down motor neurons to a neuromuscular junction

32

Neuromuscular Junction

Where a motor neuron connects to skeletal muscle

33

Motor unit

A nerve fiber and all of the muscle fibers that it innervates

34

Second Step of Muscle Fiber Contraction

Acetylcholine (ACh) is released from the neurons and bind to the muscle fibers. (Synaptic vesicles of the neuron contain ACh, a neurotransmitter, where it binds with receptor on the sarcolemma)

35

Third Step of Muscle Fiber Contraction

Binding of ACh stimulates impulses down the T-tibules causing calcium to be released from the sarcoplasmic reticulum

36

Fourth Step of Muscle Fiber Contraction

Calcium complex (troponin) modifies tropomyosin, exposing binding site

37

Fifth Step of Muscle Fiber Contraction

Myosin head binds with actin (thanks to ADP + P)

38

Sixth Step of Muscle Fiber Contraction

ADP + P are released, resulting in a power stroke

39

Seventh Step of Muscle Fiber Contraction

Additional ATP allows for myosin head to return to resting position and calcium to be pumped back into sarcoplasmic reticulum

40

Electromyogram (EMG)

Method of detecting changes in ions associated with muscle contraction

41

Electrical voltages

Difference in charge from place to place - can be detected on surface of skin

42

Motor unit

A nerve fiber and all of the muscle fibers it stimulates - "all or none"

43

Motor Unit Recruitment

Increases the strength of contraction by increasing the number of motor units in use

44

Fatigue sets in when...

...you have recruited same motor units for a while and depleted energy (ATP)

45

Muscle twitch is...

A single motor unit contraction, caused by infrequent electrical impulses, and lasts a fraction of a second.

46

Summation

Increase in muscle contraction until maximum sustained contraction (tetanus) is reached, and lasts until fatigue (muscle relaxes despite stimulation due to depletion of energy reserves).

47

Tetanus

Maximal sustained contraction

48

Fatigue

Decrease in a muscle's ability to generate force, when the muscle relaxes despite stimulation due to depletion of energy reserves.

49

Four sources of ATP for muscle contraction...

Stored in muscle fibers
Creatine-phosphate pathway
Fermentation
Cellular Respiration

50

Creatine-phosphate pathway

Fastest way to acquire ATP but only sustains cell for seconds; builds up when a muscle is resting (anaerobic).

51

Fermentation

Fast-acting but results in lactate build-up (anaerobic)

52

Cellular Respiration

Not an immediate source of ATP, but best long term source (aerobic)

53

Myoglobin

Protein that transports oxygen directly to mitochondria of muscle cells

54

Fast Twitch Fiber Characteristics

Creatine-Phosphate pathway and fermentation for ATP
Fewer Mitochondria
Light Color
Fewer blood vessels
Little myoglobin

55

Slow Twitch Fiber Characteristics

Cellular Respiration for ATP
More mitochondria
Dark color
More blood vessels
More myoglobin

56

Fast Twitch Muscle Characteristics

Anaerobic
Explosive Power
Fatigues Easily

57

Slow Twitch Muscle Characteristics

Is Aerobic
Steady Power
Has Endurance

58

Spasms

Sudden, involuntary muscle contractions that are usually painful

59

Seizure/Convulsion

Multiple spasms of skeletal muscles