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Flashcards in Chapter 10 - Muscular Tissue Deck (193)
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61

 A small amount of ____________in the muscle due to weak contractions of motor units 

 Small groups of motor units are alternatively active and inactive in a constantly shifting pattern to sustain muscle ____________ to keep skeletal muscle firm

tautness (tension)

tone

 

62

(2) types of contractions

1) isotonic

2) isometric

63

Isotonic Contraction

tension developed remains constant while the muscle changes its length

 Used for body movements and for moving objects

ie. Picking a book up off a table 

64

Isometric Contraction

The tension generated is not enough for the object to be moved and the muscle does not change its length

tension increases without a change in muscle length

 Holding a book steady using an outstretched arm 

65

(2) types of isotonic contraction

1) concentric 

2) eccentric

66

concentric isotonic contraction

tension generated is great enough to overcome resistance of object to be moved, muscle shortens & pulls on another structure to produce movement & to reduce angle at a joint

67

eccentric muscle contraction

length of muscle increases 

68

Muscle fibers vary in their content of ___

myoglobin  - red-coloured protein that binds oxygen in muscle fibers

69

Red Muscle Fibers

skeletal muscle fibers that have a high myoglobin content 

- appear darker (dark meat in chicken legs & thighs) 

contain more mitochondria 

supplied by more blood capillaries

70

White Muscles Fibers 

Have a low myoglobin content

Appear lighter (white meat in chicken breasts) 

71

Muscle fibers contract at different speeds, and vary in how quickly they fatigue.

Muscle fibers are classified into (3) main types based on structural & functional characteristics.

1) Slow oxidative (SO) fibers

2) Fast oxidative-glycolytic (FOG) fibers

 3) Fast glycolytic (FG) fibers 

72

1) Slow oxidative (SO) fibers

diameter size?

power?

appearance?

generate ATP by?

speed of contraction?

time until fatigue?

for what activities?

smallest

least powerful

dark red (more myoglobin)

mainly aerobic cellular respiration

slow contraction speed (last 100-200 msec)

very resistant to fatigue

capable of prolonged, sustained contractions for many hours 

adapted for maintaining posture, aerobic, endurance-type activities (running marathons)

73

2) Fast oxidative-glycolytic (FOG) fibers

diameter?

contains? appearance?

generates ATP by?

resistance to fatigue?

speed of contraction?

contribute to which activities?

intermediate diameter size

lots of myoglobin & many blood capillaries 

aerobic cellular respiration but also anaerobic glycolysis

moderately high resistance to fatigue

faster contraction speed ( < 100 msec)

walking & sprinting

74

 3) Fast glycolytic (FG) fibers 

diameter?

strength?

contains? appearance?

generates ATP by?

resistance to fatigue?

adapted for?

largest 

most powerful contractions

low myoglobin, few blood capillaries & mitochondria

white in colour

mainly by glycolysis 

fibers contract strongly & quickly

fatigue quickly

intense anaerobic movements of short duration (weight lifting) 

75

Most muscles are a mixture of all 3 types of muscle fibers

Proportions vary, depending on ....(3)

1) action of the muscle

2) the person ’s training regimen

3) genetic factors

76

Postural muscles of the neck, back, and legs have a high proportion of ____________fibers 

slow-oxidative (SO)

77

Muscles of the shoulders and arms have a high proportion of ____________fibers

Fast-Glycolytic (FG) 

78

 Leg muscles have large numbers of both ____________and ____________fibers 

Slow-Oxidative (SO) and Fast Oxidative-Glycolytic (FOG) 

79

Various types of exercises can induce changes in muscle fibers

1) ____________exercise transforms some FG fibers into FOG fibers (does not increase muscle mass) 

1) endurance 

80

 Exercises that require short bursts of strength produce an increase in the size of ___ fibers

Fast Glycolytic (FG)

81

1)  Individuals with a higher proportion of FG fibers  excel in ____________activity ( 2 examples)

2) Individuals with higher percentages of SO fibers excel in ____________activities (2 examples) 

1) intense activity  (weight lifting, sprinting) 

2) endurance activity (long-distance running) 

82

Muscle enlargement (hypertrophy) due to increased...

 synthesis of thick and thin filaments  

83

Cardiac Muscle Tissue is the principal tissue in the ___ wall 

heart wall

84

Cardiac Muscle Tissue

what connects the ends of cardiac muscle fibers to one another?

intercalated discs

85

Cardiac Muscle fibers have the same arrangedment of actin & myosin & same bands, zones & Z discs as skeletal muscle fibers but intercalated discs are unique to cardiac muscle fibers. 

These discs contain (2) 

1) desmosomes - hold fibers together 

2) gap junctions - allow muscle action potentials to spread from one cardiac muscle fiber to anotehr 

86

Cardiac muscle tissue contracts when stimulated by its own ____________muscle fibers

autorhythmic

87

 major physiological difference between cardiac and skeletal muscle tissue

continuous, rhythmic activity

88

Contractions of cardiac muscle last ___ than a skeletal muscle twitch

longer

89

Cardiac muscle depends on _____ to generate ATP

aerobic respiration

many mitochondria

requires constant supply of oxygen 

90

Smooth Muscle Tissue 

usually activated ___

Action potentials are spread through the fibers by ____________junctions

Fibers are stimulated by certain ___ , __, or ___ signals 

involuntarily

gap junctions

neurotransmitter, hormone or autorhythmic signals