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BIO 235 > Chapter 10 > Flashcards

Chapter 10 Flashcards

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Biology 101 flashcards
1
Q

The scientific study of muscles is known as:

A

myology

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2
Q

Skeletal muscle tissue

A

is so named because most skeletal muscles move the bones of the skeleton. Skeletal muscle tissue is
striated, voluntary

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3
Q

Striated

A

Alternating light and dark protein bands (striations) are seen when the tissue is examined with a microscope

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4
Q

cardiac muscle tissue

A

forms most of the heart wall. Cardiac muscle is also striated, but its action is
involuntary. The alternating contraction and relaxation of the heart
is not consciously controlled. Rather, the heart beats because it
has a natural pacemaker that initiates each contraction. This built-in
rhythm is termed autorhythmicity

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5
Q

Smooth muscle tissue

A

located in the walls of hollow internal structures, such as blood vessels, airways, and most organs in the abdominopelvic cavity. It is also found in the skin, attached to
hair follicles. Nonstriated, involuntary

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6
Q

Four Key functions of Muscular Tissue

A

Producing body movements, Stabilizing body positions, Storing and moving substances within the body, Generating heat

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7
Q

Special Properties of Muscular Tissue

A

Electrical excitability, Contractility, Extensibility, Elasticity

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8
Q

Each of your skeletal muscles is a separate organ composed of hundreds to thousands of cells, which are called:

A

muscle fibers (myocytes)

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9
Q

subcutaneous layer or hypodermis

A

Connective Tissue, separates muscle from skin, is composed of areolar connective tissue and adipose tissue. It provides a pathway for nerves, blood vessels, and lymphatic vessels to enter and exit muscles.

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10
Q

Fascia

A

Connective Tissue, is a dense sheet or broad band of irregular connective tissue that lines the body wall and limbs and supports and surrounds muscles and other organs of the body.

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11
Q

layers of connective tissue

A

Empimysium, Perimysium, Endomysium

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12
Q

Functions of Muscular Tissues:

A

Producing Motions, Stabilizing body positions, Storing and moving substances within the body, Generating heat (thermogenesis)

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13
Q

When the connective tissue elements
extend as a broad, flat sheet, it is called an:

A

aponeurosis

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14
Q

Skeletal muscles are supplied with:

A

nerves and blood vessels

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15
Q

The neurons that stimulate skeletal
muscle to contract are

A

somatic motor neurons.

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16
Q

The multiple nuclei of a skeletal muscle fiber are located just beneath
the:

A

sarcolemma

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17
Q

sarcolemma

A

the plasma membrane of a muscle cell

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18
Q

transverse (T)
tubules

A

Thousands of tiny invaginations of the sarcolemma, tunnel in from the surface toward the center of each
muscle fiber.

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19
Q

Within the sarcolemma is the:

A

sarcoplasm

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20
Q

sarcoplasm

A

the cytoplasm of a muscle fiber. Sarcoplasm includes a substantial amount of
glycogen, which is a large molecule composed of many glucose molecules. Also contains a protein called myoglobin

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21
Q

Myoglobin

A

protein, found only in muscle, binds oxygen molecules that diff use into muscle fibers from interstitial fluid. Myoglobin releases oxygen when it is needed by the mitochondria for ATP production.

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22
Q

At high magnification, the sarcoplasm appears stuffed with little threads.
These small structures are the:

A

myofibrils

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23
Q

A fluid-filled system of membranous sacs called the:

A

sarcoplasmic reticulum (SR) encircles each
myofibril

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24
Q

Dilated end sacs of the sarcoplasmic reticulum called:

A

terminal cisterns butt against the T tubule from both sides.

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25
Q

A transverse tubule
and the two terminal cisterns on either side of it form a:

A

triad

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26
Q

Within myofibrils are
smaller protein structures called:

A

filaments or myofilaments
Thin (actin) and Thick (myosin)

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27
Q

Filaments are composed in compartments called:

A

sarcomeres

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28
Q

Narrow, plate-shaped regions of dense protein material called:

A

Z discs- separate one sarcomere from the next

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29
Q

The darker middle part of the sarcomere is the

A

A band- extends the entire length of the thick
filaments

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30
Q

Toward each end of the A band is a:

A

zone of overlap, where the thick and thin filaments lie side by side

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31
Q

I band

A

is a lighter, less dense area that contains the rest of the thin filaments but no thick filaments and a Z disc passes through the center of each I band.

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32
Q

H zone

A

in the center of each A band contains thick but not thin filaments.

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33
Q

Supporting proteins that hold the thick filaments together at the center
of the H zone form the

A

M zone- (M for middle of the sarcomere)

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34
Q

The two contractile proteins in muscle are:

A

Myosin and Actin

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35
Q

Motor proteins

A

pull various cellular structures to achieve movement by converting the chemical energy in ATP to the mechanical energy of motion, that is, the production of force

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36
Q

myosin tail

A

points towards the m line in the center of the sarcomere

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37
Q

The two projections of each myosin molecule (golf club heads) are
called

A

myosin heads

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38
Q

The main component of the thin filament is the protein:

A

actin

39
Q

On each actin
molecule is a

A

myosin-binding site, where a myosin head can attach.

40
Q

Two regulatory proteins of the thin filaments:

A

tropomyosin and troponin

41
Q

muscle contains
about a dozen

A

structural proteins- which contribute to the alignment, stability, elasticity, and extensibility of myofibrils. Several key structural proteins are titin, α-actinin, myomesin, nebulin, and dystrophin.

42
Q

Titin

A

the third most plentiful protein in skeletal
muscle (aft er actin and myosin). This molecule’s name reflects its huge
size. With a molecular mass of about 3 million daltons, titin is 50 times
larger than an average-sized protein.

43
Q

The Sliding Filament Mechanism

A

Muscle contraction occurs because myosin heads attach to and “walk”
along the thin filaments at both ends of a sarcomere, progressively pulling the thin filaments toward the M line. As the thin filaments slide inward, the I band and H zone narrow and eventually disappear altogether when the muscle is maximally contracted.

44
Q

The Contraction Cycle

A

ATP hydrolysis, Attachment of myosin to actin, Power stroke, Detachment of myosin from actin

45
Q

Excitation–Contraction Coupling

A

The sequence of events that links excitation (a muscle action potential) to contraction (sliding of the
filaments)

46
Q

Voltage-gated Ca2+ channels

A

located in the T tubule
membrane; they arranged in clusters of four known as tetrads. The main role of these voltage-gated Ca2+ channels in excitation contraction coupling is to serve as voltage sensors that trigger the
opening of the Ca2+ release channels

47
Q

Ca2+ release channels

A

are present in the terminal cisternal membrane of the SR.

48
Q

The terminal cisternal membrane of the sarcoplasmic reticulum also contains

A

Ca2+-ATPase pumps

49
Q

Inside the SR, molecules of a protein known as

A

calsequestrin- bind to Ca2+, allowing even more Ca2+ to be sequestered (stored) within
the SR.

50
Q

Length–Tension Relationship

A

indicates how the forcefulness of muscle contraction depends on the length of the
sarcomeres within a muscle before contraction begins

51
Q

The Neuromuscular Junction

A

Each somatic motor neuron has a threadlike axon that extends from the brain or spinal cord to a group of skeletal muscle fibers. A muscle fiber
contracts in response to one or more action potentials propagating
along its sarcolemma and through its system of T tubules. Muscle
action potentials arise at the neuromuscular junction (NMJ)

52
Q

A synapse

A

is a region where communication occurs between two neurons, or between a neuron and
a target cell—in this case, between a somatic motor neuron and a
muscle fiber

53
Q

At most synapses a small gap, called the:

A

synaptic cleft,
separates the two cells

54
Q

Instead, the first cell communicates with the second by releasing a
chemical messenger called a

A

neurotransmitter

55
Q

At the NMJ, the end of the motor neuron, called the:

A

axon terminal,
divides into a cluster of synaptic end bulbs

56
Q

Suspended in the cytosol within each synaptic end bulb are hundreds of membrane-enclosed sacs called

A

synaptic vesicles

57
Q

Inside each synaptic vesicle are thousands of molecules of

A

acetylcholine (ACh)

58
Q

The region of the sarcolemma opposite the synaptic end bulbs,
called the

A

motor end plate

59
Q

Within each motor end plate are 30 million to 40 million:

A

acetylcholine receptors- integral transmembrane proteins to which
ACh specifically binds.

60
Q

junctional folds

A

deep grooves in the motor end plate that provide a large surface area for ACh.

61
Q

nerve impulse elicits a muscle action
potential in the following way:

A

Release of acetylcholine, Activation of ACh receptors, Production of muscle action potential, Termination of ACh activity,

62
Q

Production of ATP in Muscle Fibers

A

(1) from creatine
phosphate, (2) by anaerobic glycolysis, and (3) by aerobic respiration

63
Q

While muscle fibers are relaxed, they
produce more ATP than they need for resting metabolism. Most of the
excess ATP is used to synthesize

A

creatine phosphate- an
energy-rich molecule that is found in muscle fibers

64
Q

Creatine

A

a small, amino acid–like molecule
that is synthesized in the liver, kidneys, and pancreas and then
transported to muscle fibers.

65
Q

Anaerobic Glycolysis

A

Glycolysis occurs in the cytosol and produces a net gain of two molecules of ATP. The entire process by which the breakdown of glucose gives rise
to lactic acid when oxygen is absent or at a low concentration is referred as anaerobic glycolysis

66
Q

Aerobic Respiration

A

a series of oxygen-requiring reactions (the Krebs cycle and the electron transport chain) that produce ATP, carbon
dioxide, water, and heat

67
Q

Muscular tissue has two sources of oxygen:

A

(1) oxygen that diffuses into muscle fibers from the blood and (2) oxygen released by myoglobin within muscle fibers

68
Q

The inability of a muscle to maintain force of contraction aft er prolonged activity is called

A

muscle fatigue

69
Q

oxygen debt

A

been used to refer to the added oxygen, over and
above the resting oxygen consumption, that is taken into the body after exercise. This extra oxygen is used to “pay back” or restore metabolic conditions to the resting level in three ways: (1) to convert lactic acid back into glycogen stores in the liver, (2) to resynthesize creatine phosphate and ATP in muscle fibers, and (3) to replace the oxygen
removed from myoglobin.

70
Q

recovery oxygen uptake

A

a better term than oxygen debt for the elevated use of oxygen after exercise

71
Q

Motor unit

A

consists of a somatic motor neuron plus all of the skeletal muscle fibers it stimulates

72
Q

twitch contraction

A

the brief contraction of all muscle fibers in a motor unit in response to a single action potential in its motor neuron.

73
Q

The record of a muscle contraction is called a

A

myogram

74
Q

4 periods of muscle contractions

A

latent period, contraction period, relaxation period and refractory period

75
Q

This phenomenon, in which stimuli arriving at
different times cause larger contractions, is called

A

wave summation

76
Q

When a
skeletal muscle fiber is stimulated at a higher rate of 80 to 100 times
per second, it does not relax at all. The result is

A

fused tetanus- a sustained contraction in which individual twitches
cannot be detected

77
Q

When a skeletal muscle fiber is stimulated at a rate of 20 to
30 times per second, it can only partially relax between stimuli. The
result is a sustained but wavering contraction called

A

unfused (incomplete) tetanus

78
Q

The process in which the number of active motor units increases
is called

A

motor unit recruitment

79
Q

Muscle Tone

A

a small amount of tautness or tension in the muscle due to
weak, involuntary contractions of its motor units.

80
Q

When the motor neurons serving a skeletal muscle
are damaged or cut, the muscle becomes

A

flaccid

81
Q

Muscle contractions may be either

A

isotonic or isometric

82
Q

isotonic contraction

A

the tension (force of contraction) developed in the muscle remains almost constant while the muscle changes its length

83
Q

Two types of isotonic contractions:

A

eccentric and concentric

84
Q

isometric contraction

A

the tension generated is not enough to exceed the resistance of the object to be moved, and the muscle does not change its length.

85
Q

Types of skeletal muscle fibers

A

red muscle fibers, white muscle fibers

86
Q

Slow oxidative (SO) fibers:

A

appear dark red because they contain large amounts of myoglobin and many blood capillaries. Because they have many large mitochondria, SO fibers generate ATP mainly
by aerobic respiration, which is why they are called oxidative fibers.

87
Q

Fast oxidative–glycolytic fibers

A

largest fibers. Like slow oxidative fibers, they contain large amounts of myoglobin and many blood capillaries. Thus, they also have a dark red
appearance. FOG fibers can generate considerable ATP by aerobic respiration, which gives them a moderately high resistance to fatigue.

88
Q

Fast glycolytic (FG) fibers

A

low myoglobin content, relatively
few blood capillaries, and few mitochondria, and appear white in
color. They contain large amounts of glycogen and generate ATP
mainly by glycolysis. Due to their ability to hydrolyze ATP rapidly,
FG fibers contract strongly and quickly. These fast-twitch fibers are
adapted for intense anaerobic movements of short duration, such
as weight lifting or throwing a ball, but they fatigue quickly.

89
Q

cardiac muscle tissue

A

The principal tissue in the heart wall

90
Q

intercalated
discs

A

unique to cardiac muscle fibers. These microscopic structures are irregular
transverse thickenings of the sarcolemma that connect the ends of
cardiac muscle fibers to one another.

91
Q

Intercalated discs contain:

A

desmosomes,
which hold the fibers together, and gap junctions, which allow muscle action potentials to spread from one cardiac muscle fiber to another

92
Q

smooth muscle tissue

A

involuntary, two types: visceral (most common) and multi-unit smooth muscle tissue

93
Q
A

BIO 235 (10 decks)

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