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A&P Exam 2 > Chapter 10 - Muscle Tissue - PART 4 > Flashcards

Chapter 10 - Muscle Tissue - PART 4 Flashcards

1
Q

We can consider muscle performance in terms of ____ and ____

A

force and endurance

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2
Q

What is the difference between force and endurance?

A

force = the maximum amount of tension produced by a particular muscle or muscle group

endurance = the amount of time during which the individual can perform a particular activity

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3
Q

What 4 things determine the performance capability of any skeletal muscle?

A

-the type
-the distribution
-the size of muscle fibers in the muscle
-the physical conditioning of training

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4
Q

The human body has ____ major types of skeletal muscle fibers:

A

-fast fibers
-slow fibers
-intermediate fibers

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5
Q

Most of the skeletal muscle fibers in the body are….

A

fast fibers

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6
Q

Why are “fast fibers” given that name?

A

because they can reach peak twitch tension in 0.01 seconds after stimulation

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7
Q

Give some characteristics of fast fibers

A

large in diameter
densely packed myofibrils
large glycogen reserves
relatively few mitochondria

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8
Q

Muscles dominated by fast fibers produce _____ contractions. Explain

A

POWERFUL contractions because the tension produced by a muscle fiber is directly proportional to the number of myofibrils

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9
Q

What is the drawback to fast fibers?

A

they fatigue rapidly because their contractions use ATP in massive amounts, and they have relatively few mitochondria to generate ATP

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10
Q

Prolonged activity of fast fibers is supported primarily by….

A

ANAEROBIC respiration

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11
Q

Slow fibers only have about ____ the diameter of fast fibers and take ____ time as long to reach peak tension after stimulation

A

half the diameter, 3 times as long

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12
Q

What is the good thing about slow fibers when comparing them to fast fibers?

A

they are specialized in ways that enable them to continue contracting long after a fast fiber becomes fatigued

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13
Q

Which fiber has the most mitochondria and thus is primarily supported by aerobic metabolism?

A

slow fibers

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13
Q

Which fiber has the most mitochondria and thus is primarily supported by aerobic metabolism?

A

slow fibers

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14
Q

How is it that slow fibers have a dramatically higher oxygen supply? What does this allow them to do?

A

slow fibers have an extensive network of capillaries. Helps with aerobic respiration

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15
Q

Slow muscle fibers contain the pigment ____ which does what?

A

MYOGLOBIN which is similar to hemoglobin in that it reversibly binds oxygen.

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16
Q

Slow muscles contain a lot of myoglobin. What does this enable them to do?

A

resting slow fibers can hold a substantial amount of oxygen reserves that can be mobilized during a contraction

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17
Q

What color are skeletal muscles dominated by slow fibers? why?

A

dark red because they have an extensive capillary supply and a high concentration of myoglobin

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18
Q

Are there more glycogen reserves in slow or fast fibers?

A

fast because slow fibers mainly break down lipids for energy

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19
Q

In appearance, intermediate fibers closely resemble….

A

fast fibers because they contain little myoglobin and are relatively pale

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20
Q

which are more resistant to fatigue - fast fibers or intermediate fibers?

A

intermediate

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21
Q

Muscles dominated by fast fibers appear ____ and are often called ____

A

appear PALE and are often called WHITE MUSCLES

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22
Q

Muscles dominated by slow fibers are known as…..

A

red muscles

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23
Q

Explain why chickens have “dark meat” and “light meat”

A

light meat = for quick movements such as flying. Dominated by fast fibers using anaerobic glycolysis

dark meat = for all day movements such as walking. dominated by slow fibers/ aerobic metabolism

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24
Q

Most human muscles appear _____. Why?

A

pink because they contain a mixture of fiber types

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25
Q

Where are there NO slow fibers in the human body?

A

the eye and hand, where swift, but brief contractions are required

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26
Q

Many __ and ___ muscles are dominated by slow fibers

A

back and calf

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27
Q

What determines the %age of fast and slow fiber in each muscle?

A

our genes

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28
Q

Athletic training can increase the ratio of ____ to ______

A

intermediate fibers to fast fibers

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29
Q

As a result of repeated, exhausted stimulation, muscle fibers develop more _____, _____, and _____

A

more mitochondria, higher concentration of glycolytic enzymes, and more glycogen reserves (have more MYOFIBRILS- EACH CONTAINING MORE THIN AND THICK FILAMENTS)

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30
Q

The effects of repeated, exhaustive stimulation is the net effect of _____

A

hypertrophy (enlargement of the stimulated muscle)

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31
Q

In hypertrophy, does the # of muscle fibers change significantly?

A

no-the muscle as a whole enlarges because each muscle fiber increases in diameter

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32
Q

What is atrophy?

A

a skeletal muscle that is not regularly stimulated by a motor neuron loses muscle tone and mass. The muscle becomes flaccid and the muscle fibers become smaller and weaker

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33
Q

Is muscle atrophy reversible?

A

at first it is - but dying muscle fibers cannot be replaced

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34
Q

Skeletal muscles depend on ____ for stimulation

A

motor neurons

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35
Q

What happens to muscles in POLIO?

A

the virus attacks motor neurons in the spinal cord and brain, causing muscular paralysis and atrophy

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36
Q

Anaerobic endurance is the length of time in which….

A

muscular contraction can continue to be supported by glycolysis and by the existing energy reserves

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37
Q

Conditioning for anaerobic endurance improves an individual’s _____

A

power

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38
Q

Anaerobic endurance is limited by which 3 things?

A

-The amount of ATP and CP available
-The amount of glycogen available for breakdown
-the ability of the muscle to tolerate the lactic acid generated during the anaerobic period

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39
Q

50 meter swim
pole vaulting
competitive weight lifting

-does this require above average levels of AEROBIC or ANAEROBIC endurance?

A

ANAEROBIC - brief, intense workouts that stimulate muscle hypertrophy

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40
Q

Aerobic endurance is the amount of time a muscle can….

A

contract while supported by mitochondrial activities

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41
Q

Do AEROBIC activities promote muscle hypertrophy?

A

NO

42
Q

Which type of endurance improves an individual’s ability to continue an activity for longer periods of time?

A

aerobic endurance

43
Q

During exercise, blood vessels in the skeletal muscles do what?

A

they dilate to increase more blood flow and bring oxygen and nutrients to the active muscle tissue

44
Q

Why are warm up periods important before a workout?

A

because they stimulate circulation in the muscles before the serious workout begins and activate the enzyme that breaks down glycogen to release glucose

45
Q

What is a preferred energy source for endurance atheletes?

A

glucose - thats why they “bulk up” on carbohydrates several days before the event

46
Q

Trying to improve aerobic endurance generally involves….

A

sustained levels of muscular activity such as jogging

47
Q

improvements in aerobic endurance can result from 2 factors:

A
  1. Alterations in the characteristics of muscle fibers
  2. Improvements in cardiovascular performance
48
Q

“alterations in the characteristics of muscle fibers improve aerobic endurance”
EXPLAIN THIS STATEMENT

A

fast fibers develop into characteristics of intermediate fibers which improves aerobic endurance

49
Q

“Improvements in cardiovascular performance improve aerobic endurance”
EXPLAIN THIS STATEMENT

A

-blood flow is accelerated increasing delivery of oxygen to the active muscles
-increase in capillaries, improving blood flow at the cellular level

50
Q

why is “cross-training” recomended?

A

alternate an aerobic activity with an anaerobic activity
-this enhances health by both increasing muscle mass and aerobic endurance

51
Q

Identify the 3 types of skeletal muscle fibers

A

-fast fibers(white muscle fibers)
-slow fibers (red muscle fibers)
-intermediate fibers

52
Q

Why would a sprinter experience muscle fatigue before a marathon runner would?

A

A sprinter requires large amounts of energy for a short burst of time. To supply this energy, the sprinter uses anaerobic metabolism which is less efficient and produces acidic waste products which leads to muscle fatigue

however, marathon runners derive most of their energy from aerobic metabolism which is more efficient and produces fewer waste products

53
Q

Which activity would be more likely to create an oxygen debt:

-swimming laps
-lifting weights

A

Activities that require short periods of strenuous activity produce a greater oxygen debt because such activities rely heavily on anaerobic metabolism.
WEIGHT LIFTING WOULD PRODUCE AN OXYGEN DEBT

54
Q

Which type of muscle fibers would you expect to predominate in the large leg muscles of someone who excels at endurance activities such as cycling or long distance running?

A

individuals who excel at endurance activities have a higher than normal percentage of SLOW FIBERS. Slow fibers are better adapted to this type of activity than fast fibers, which are less vascular and fatigue faster

55
Q

Like skeletal muscle fibers, cardiac muscle cells contain _____ and ______

A

organized myofibrils with the presence of many aligned sarcomeres(gives a striated appearance)

56
Q

Name some differences between cardiac muscle cells and skeletal muscle fibers

A

-cardiac muscle cells are smaller
-cardiac muscle cells are typically branched while skeletal are not
-cardiac cells only have 1 nucleus
-t tubules encircle the sarcomeres at Z LINES rather than at the zones of overlap
-no triads
-the SR of a cardiac cell lacks terminal cisternae
-totally dependent on aerobic metabolism
-have intercalated discs

57
Q

Describe the similarity and difference between the action potential in a skeletal muscle cell and a cardiac muscle cell

A

-in both, action potential triggers the release of calcium ions from the SR and the contraction of sarcomeres

-however, an action potential in cardiac muscle cells also makes the sarcolemma more permeable to extracellular calcium ions. Their contractions require both intracellular and extracellular calcium ions

58
Q

cardiac muscle cells are almost totally dependent on ____ metabolism for the energy they need to continue contracting

A

aerobic

59
Q

The sarcoplasm of a cardiac muscle cell contains large numbers of _____, as well as abundant reserves of _____ which store oxygen needed to break down energy reserves in times of peak activity

A

mitochondria, myoglobin

60
Q

What is present at an intercalated disc?

A

the sarcolemmas of 2 adjacent cardiac muscle cells are bound together by GAP JUNCTIONS and DESMOSOMES

61
Q

the gap junctions at an intercalated disc allows for…..

A

ions and small molecules to move from one cell to another (action potential)

62
Q

at an intercalated disc, the ____ are essentially locked together

A

myofibrils

63
Q

cardiac muscle cells contract without _____ stimulation. What is the term for this?

A

cardiac muscle cells contract without NEURAL STIMULATION. this property is called AUTOMATICITY

64
Q

What cells determine the timing of contractions of cardiac muscle cells?

A

pacemaker cells

65
Q

____ can alter the pace set by the pacemaker cells and adjust the amount of tension produced during a contraction

A

the nervous system

66
Q

Do cardiac muscle cell contractions last longer or shorter than the contractions of skeletal muscle fibers?

A

cardiac lasts about 10x longer

67
Q

do cardiac muscle cells readily fatigue?

A

NO

68
Q

Do cardiac muscle cells undergo wave summation or tetanic contractions? why or why not

A

NO.
A heart in a sustained tetanic contraction could not pump blood

69
Q

What does it mean that cardiac muscle cell is called a “functional syncytium”

A

cardiac muscle cells are joined by gap junctions, which allows ions and small molecules to flow directly between cells. as a result, action potentials generated in 1 cell spread rapidly to adjacent cells. This, all the cells contract simultaneously as if they were a single unit (a synctium)

70
Q

Smooth muscle tissue forms ______ around other tissues in almost every organ

A

sheets

71
Q

In the digestive and urinary systems, rings of smooth muscle, called _____ regulate the movement of materials along internal passageways

A

SPHINCTERS

72
Q

Smooth muscles play a role in which 6 body systems?

A

-Integumentary
-cardiovascular
-digestive
-urinary
-respiratory
-reproductive

73
Q

how does smooth muscle play a role in the integumentary system

A

smooth muscles around blood vessels regulate the flow of blood to the superficial dermis. smooth muscles of the arrector pili elevate hairs

74
Q

how does smooth muscle play a role in the cardiovascular system?

A

smooth muscles encircling blood vessels control the distribution of blood and help regulate blood pressure

75
Q

how does smooth muscle play a role in the respiratory system?

A

smooth muscles contract or relax to alter the diameters of the respiratory passageways and change resistance to airflow

76
Q

how does smooth muscle play a role in the digestive system?

A

smooth muscle in the walls of the digestive tract play a role in moving materials along the tract

77
Q

All 3 types of muscle tissue contain __ and ___

A

actin and myosn

78
Q

All 3 types of muscle tissue contain __ and ___

A

actin and myosin

79
Q

Are actin and myosin organized in sarcomeres in smooth muscle cells?

A

NO

80
Q

a smooth muscle cell is _____ shaped and _____

A

spindle shaped and unstriated

81
Q

Where are thick filaments in a smooth muscle cell?

A

they are scattered throughout the sarcoplasm

82
Q

Where are thin filaments in smooth muscle cells?

A

thin filaments are attached to DENSE BODIES - structures distributed throughout the sarcoplasm in a network of intermediate filaments composed of the protein DESMIN

83
Q

When a contraction occurs in a smooth muscle cell….

A

the cell twists like a corkscrew because dense bodies are not arranged in straight lines

84
Q

Adjacent smooth muscle cells are bound together at…..

A

dense bodies, transmitting the contractile forces from cell to cell throughout the tissue

85
Q

smooth muscles are surrounded by ___ tissue

A

connective

86
Q

do collagen fibers in SMOOTH muscle tissue unite to form tendons or aponeurosis?

A

NO

87
Q

What is the trigger for smooth muscle contraction?

A

the appearance of free calcium ions in the sarcoplasm

88
Q

Once in the sarcoplasm of a smooth muscle cell, calcium ions interact with _______, a calcium binding protein

A

calmodulin

89
Q

Calmodulin then activates the enzyme _____

A

myosin light change kinase——enables myosin heads to attach to actin

90
Q

The ability of smooth muscle to function over a wide range of lengths is called ____

A

plasticity

91
Q

Plasticity is especially important in ___ organs

A

digestive, such as the stomach, that greatly change in volume

92
Q

Is the power of contractions in smooth muscle cells comparable with those of skeletal muscle fibers?

A

despite lacking sarcomeres, YES

93
Q

Smooth muscle cells are either classified as ______ or _____

A

multiunit or visceral

94
Q

What is a multiunit smooth muscle cell?

A

they are innervated in motor neurons comparable to those of skeletal muscles, but each smooth muscle cell can be attached to more than one motor neuron

95
Q

visceral smooth muscle cells lack a direct contact with any _______

A

motor neuron

96
Q

Multiunit smooth muscle cells resemble skeletal muscle fibers and cardiac cells in that….

A

neural activity produces an action potential that travels over the sarcolemma

97
Q

multiunit smooth muscle cells, however, are different than skeletal or cardiac cells in that….

A

smooth muscle cells contract more slowly

98
Q

Where are multiunit smooth muscle cells found?

A

-in the iris of the eye
-walls of large arteries
-portions of the male reproductive tract
-arrector pili muscles of the skin

99
Q

multiunit smooth muscles do NOT typically occur in….

A

the digestive tract

100
Q

visceral smooth muscle cells are arranged in ___ or ____

A

sheets or layers

101
Q

Identify the structural characteristics of smooth muscle tissue

A

lack sarcomeres and thus are nonstriated. Additionally, the thin filaments are anchored to dense bodues

102
Q

why are cardiac and smooth muscle contractions more affected by extracellular calcium than skeletal muscle contractions?

A

because in cardiac and smooth muscles, most of the calcium ions that trigger a contraction come from the extracellular fluid. Whereas in skeletal muscle, most of the calcium ions come from the sarcoplasmic reticulum

103
Q

Why can smooth muscles contract over a wider range of resting lengths than a skeletal muscle can?

A

the looser organization of actin and myosin filaments in smooth muscle allows smooth muscle to contract over a wider range of resting lengths

A&P Exam 2 (19 decks)

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