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Chapter 9 Muscles and Muscle Tissue > Muscles and Muscles Tissue Part C > Flashcards

Muscles and Muscles Tissue Part C Flashcards

1
Q

Factors of Muscle Contraction

A

Force of contraction depends on number of cross bridges attached, which is affected by four factors:

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2
Q

Number of muscle fibers stimulated

A

(recruitment): the more motor units recruited, the greater the force.

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3
Q

Relative size of fibers

A

the bulkier the muscle, the more tension it can develop

Muscle cells can increase in size (hypertrophy) with regular exercise

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4
Q

Frequency of stimulation

A

the higher the frequency, the greater the force.

Stimuli are added together

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5
Q

Degree of muscle stretch

A

muscle fibers with sarcomeres that are 80–120% their normal resting length generate more force

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6
Q

If sarcomere is less than 80%

A

resting length, filaments overlap too much, and force decreases.

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7
Q

If sarcomere is greater than 120%

A

of resting length, filaments do not overlap enough so force decreases

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8
Q

How fast a muscle contracts and how long it can stay contracted is influenced by:

A

Muscle fiber type
Load
Recruitment

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9
Q

Muscle fiber type Classified according to two characteristics

A

Speed of contraction.
Oxidative fibers.
Glycolytic fibers

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10
Q

Speed of contraction

A

– slow or fast fibers

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11
Q

According to

Speed at which

A

myosin ATPases split ATP

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12
Q

According to pattern

A

Pattern of electrical activity of motor neurons

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13
Q

Metabolic pathways

A

used for ATP synthesis

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14
Q

Oxidative fibers

A

use aerobic pathways

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15
Q

Glycolytic fibers:

A

use anaerobic glycolysis

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16
Q

skeletal muscle fibers can be classified into three types:

A

Slow oxidative fibers, fast oxidative fibers, or fast glycolytic fibers

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17
Q

Most muscles contain

A

contain mixture of fiber types, resulting in a range of contractile speed and fatigue resistance

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18
Q

All fibers in one motor unit

A

are the same type

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19
Q

Genetics dictate

A

individual’s percentage of each

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20
Q

Muscle fiber type

A

Different muscle types are better suited for different jobs

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21
Q

Slow oxidative fibers example

A

: low-intensity, endurance activities

Example: maintaining posture

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22
Q

Fast oxidative fibers and example

A

medium-intensity activities

Example: sprinting or walking

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23
Q

Fast glycolytic fibers and example

A

short-term intense or powerful movements

Example: hitting a baseball

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24
Q

Load

A

muscles contract fastest when no load is added

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25
Q

The greater the load

A

the shorter the duration of contraction

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26
Q

The greater the load

A

the slower the contraction

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27
Q

Recruitment

A

the more motor units contracting, the faster and more prolonged the contraction

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28
Q

Aerobic (Endurance) Exercise

A

such as jogging, swimming, biking

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29
Q

leads to increased

A

Muscle capillaries
Number of mitochondria
Myoglobin synthesis

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30
Q

Results in

A

greater endurance strength, and resistance to fatigue

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31
Q

May convert fast

A

glycolytic fibers into fast oxidative fibers.

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32
Q

Resistance exercise (typically anaerobic),

A

such as weight lifting or isometric exercises

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33
Q

Leads to

A

Muscle hypertrophy.

Due primarily to increase in fiber size.

Increased mitochondria, myofilaments, glycogen stores, and connective tissue.

Increased muscle strength and size

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34
Q

Disuse atrophy

A

(degeneration and loss of mass).

Due to immobilization or loss of neural stimulation.

Can begin almost immediately.

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35
Q

Disuse atrophy

A

Muscle strength can decline 5% per day

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36
Q

Paralyzed muscles

A

may atrophy to one-fourth initial size

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37
Q

Fibrous connective tissue/ Rehabilitation

A

replaces lost muscle tissue.

Rehabilitation is impossible at this point.

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38
Q

Smooth Muscle location

A

Found in walls of most hollow organs.

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39
Q

Smooth Muscle found

A

Respiratory, digestive, urinary, reproductive, circulatory (except in smallest of blood vessels) except heart

40
Q

Most smooth muscle

A

organized into sheets of tightly packed fibers

41
Q

what are the two layer of sheet smooth muscles contains?

A

Longitudinal layer

Circular layer

42
Q

Longitudinal layer

A

fibers run parallel to long axis of organ

Contraction causes organ to shorten

43
Q

Circular layer

A

fibers run around circumference of organ

Contraction causes lumen of organ to constrict

44
Q

Alternating contractions and relaxations of layer

A

layers mix and squeeze substances through lumen of hollow organs

45
Q

Smooth muscle fibers and the size

A

fibers are spindle-shaped fibers.

thin and short

46
Q

Smooth muscle

A

Only one nucleus, no striations

47
Q

Smooth muscle lack of and contains of

A

connective tissue sheaths,

Contains endomysium only

48
Q

Smooth muscle have

A

varicosities (bulbous swellings) of nerve fibers

49
Q

Varicosities

A

store and release neurotransmitters into a wide synaptic cleft referred to as a diffuse junction

50
Q

Innervated (smooth muscles)

A

by the autonomic nervous system.

51
Q

Smooth muscle has less

A

elaborate SR

52
Q

Smooth muscles have no

53
Q

SR of smooth muscle

A

less developed than in skeletal muscle

SR does store intracellular Ca2+, but most calcium used for contraction has extracellular origins

54
Q

Sarcolemma(Smooth muscles)

A

contains pouchlike infoldings called caveolae

55
Q

Caveolae

A

contain numerous Ca2+ channels that open to allow rapid influx of extracellular Ca2+

56
Q

Smooth muscle fibers are usually electrically

A

connected via gap junctions whereas skeletal muscle fibers are electrically isolated

57
Q

Gap junctions

A

are specialized cell connections that allow depolarization to spread from cell to cell

58
Q

What does gap junction contains of and don’t contain of?

A

There are no striations and no sarcomeres, but they do contain overlapping thick and thin filaments

59
Q

In smooth muscles thick filaments and ratio

A

are fewer and have myosin heads along entire length

Ratio of thick to thin filaments (1:13) is much lower than in skeletal muscle (1:2)

60
Q

Thick filaments(smooth muscles)

A

have heads along entire length, making smooth muscle as powerful as skeletal muscle

61
Q

Smooth muscle does not have(Proteins)

A

No troponin complex

62
Q

Smooth muscle does have(proteins)

A

tropomyosin and Protein calmodulin binds Ca2+

63
Q

Thick and thin filaments arranged diagonally

A

Myofilaments are spirally arranged, causing smooth muscle to contract in corkscrew manner

64
Q

Intermediate filament–dense body network

A

Contain lattice-like arrangement of non contractile intermediate filaments that resist tension

65
Q

Dense bodies:

A

proteins that anchor filaments to sarcolemma at regular intervals
Correspond to Z discs of skeletal muscle

66
Q

During contraction of smooth muscle

A

areas of sarcolemma between dense bodies bulge outward

Make muscle cell look puffy

67
Q

Mechanism of contraction

A

Slow, synchronized contractions.

Cells electrically coupled by gap junctions.

68
Q

Mechanism of contraction(action potentials)

A

Action potentials transmitted from fiber to fiber

69
Q

Some cells

A

are self-excitatory (depolarize without external stimuli)

70
Q

Act as

A

pacemakers for sheets of muscle

71
Q

Rate and intensity of contraction

A

may be modified by neural and chemical stimuli

72
Q

Contraction in smooth muscle is similar to skeletal muscle contraction in following ways:

A

Actin and myosin interact by sliding filament mechanism

73
Q

Contraction in smooth muscle is similar to skeletal muscle contraction in following ways:

A

Final trigger is increased intracellular Ca2+ level

74
Q

Contraction in smooth muscle is similar to skeletal muscle contraction in following ways:

A

ATP energizes sliding process

75
Q

Contraction in smooth muscle is similar to skeletal muscle contraction in following ways:

A

Contraction stops when Ca2+ is no longer available.

Some Ca2+ still obtained from SR, but mostly comes from extracellular space

76
Q

Ca2+ binds

A

to calmodulin, not troponin

77
Q

Activated calmodulin

A

activates myosin kinase (myosin light chain kinase)

78
Q

Activated myosin kinase phosphorylates myosin head

A

activating it

Leads to crossbridge formation with actin

79
Q

Relaxation requires:

A

Ca2+ detachment from calmodulin
Active transport of Ca2+ into SR and extracellularly
Dephosphorylation of myosin to inactive myosin

80
Q

Energy efficiency of smooth muscle contraction

A

Slower to contract and relax but maintains contraction for prolonged periods with little energy cost.

81
Q

Most smooth muscle maintain

A

moderate degree of contraction constantly without fatiguing

Referred to as smooth muscle tone

82
Q

Makes ATP via

A

aerobic respiration pathways

83
Q

Regulation of contraction

A

Controlled by nerves, hormones, or local chemical changes

84
Q

Neural regulation

A

Neurotransmitter binding causes either graded (local) potential or action potential

85
Q

Neural regulation(results)

A

Results in increases in Ca2+ concentration in sarcoplasm

86
Q

Neural regulation(response)

A

depends on neurotransmitter released and type of receptor molecules

87
Q

One neurotransmitter

A

can have a stimulatory effect on smooth muscle in one organ, but an inhibitory effect in a different organ.

88
Q

Hormones and local chemicals

A

Some smooth muscle cells have no nerve supply

89
Q

Depolarize

A

spontaneously or in response to chemical stimuli that bind to G protein–linked receptors

90
Q

Chemical factors

A

can include hormones, high CO2, pH, low oxygen.

91
Q

Some smooth muscles

A

respond to both neural and chemical stimuli

92
Q

Response to stretch

A

Stress-relaxation response

93
Q

Stress-relaxation response

A

responds to stretch only briefly, then adapts to new length

94
Q

Stress-relaxation response functions

A

Retains ability to contract on demand

Enables organs such as stomach and bladder to temporarily store contents

95
Q

Length and tension changes

A

Can contract when between half and twice its resting length

Allows organ to have huge volume changes without becoming flabby when relaxed

Chapter 9 Muscles and Muscle Tissue (5 decks)

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