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anatomy > Lecture Exam 3 Review > Flashcards

Lecture Exam 3 Review Flashcards

1
Q

What are the functions of muscle tissue?

A

produce movement, stabilize body position/posture, regulate organ volume, generate heat, propel fluids and food matter through various body systems

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2
Q

What is the scientific study of muscles?

A

myology

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3
Q

Describe skeletal muscle tissue

A

moves bones of the skeleton, striated, mainly voluntary, controlled by somatic neurons

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4
Q

Describe cardiac muscle tissue

A

makes up most of the heart wall, striated, involuntary, autorhythmic, regulated by autonomic neurons and hormones

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5
Q

Describe smooth muscle tissue

A

located in the walls of hollow internal structures such as blood vessels, airways, and most organs in the abdominopelvic cavity, and in the skin attached to hair follicles, nonstriated, involuntary, autorhythmic in some digestive muscles, regulated by autonomic neurons and hormones

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6
Q

What are the properties of muscle tissue?

A

electrical excitability, contractility, extensibility, elasticity

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7
Q

What is electrical excitability?

A

the ability to respond to certain stimuli by producing electrical signals called action potentials

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8
Q

What is contractility?

A

the ability of muscular tissue to contract forcefully when stimulated by a nerve impulse

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9
Q

What is extensibility?

A

the ability of muscular tissue to stretch, within limits, without being damaged

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10
Q

What is elasticity?

A

the ability of muscular tissue to return to its original length and shape after contraction or extension

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11
Q

What are muscle cells called?

A

myocytes/muscle fibers

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12
Q

How does subcutaneous tissue relate to the muscles?

A

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

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13
Q

What is fascia?

A

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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14
Q

What are the functions of fascia?

A

holds muscles with similar functions together, allows free movement; carries nerves, blood vessels, and lymphatic vessels; fills spaces between muscles

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15
Q

What are the 3 protective layers of connective tissues in muscles?

A

epimysium, perimysium, endomysium

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16
Q

What is the epimysium?

A

outer layer, encircling the entire muscle, dense irregular connective tissue

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17
Q

What is the perimysium?

A

dense irregular connective tissue, surrounds groups of 10-100+ muscle fibers separating them into fascicles

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18
Q

What is the endomysium?

A

penetrates the interior of each muscle fascicle and separates individual muscle fibers from one another; mostly reticular fibers

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19
Q

What is a tendon?

A

attaches a muscle to the periosteum of a bone

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20
Q

What is an aponeurosis?

A

when connective tissue elements extend as a broad, flat sheet

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21
Q

What is sarcolemma?

A

plasma membrane of a muscle fiber

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22
Q

What are T tubules?

A

tiny tube-shaped invaginations of the sarcolemma that tunnel in from the surface toward the center of each muscle fiber, filled with interstitial fluid

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23
Q

What is sarcoplasm?

A

the cytoplasm of a muscle fiber, includes a lot of glycogen

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24
Q

What is glycogen?

A

a large molecule composed of many glucose molecules that can be used for ATP synthesis

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25
Q

What is myoglobin?

A

inside the sarcoplasm, only in muscles, binds oxygen molecules that diffuse into muscle fibers from interstitial fluid, releases oxygen when it is needed by the mitochondria for ATP production

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26
Q

What are myofibrils?

A

contractile organelles of skeletal muscle

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27
Q

What is the sarcoplasmic reticulum?

A

fluid-filled system of membranous sacs that encircle each myofibril

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28
Q

What are terminal cisterns?

A

dilated end sacs of SR that butt against the T tubule from both sides forming a triad; release of Ca2+ from the terminal cisterns triggers a muscle contraction

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29
Q

What are filaments?

A

smaller protein structures within myofibrils

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30
Q

What are thin filaments composed of?

A

actin

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31
Q

What are thick filaments composed of?

A

myosin

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32
Q

What are sarcomeres?

A

basic functional units of a myofibril

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33
Q

What 3 types of proteins form myofibrils?

A

contractile, regulatory, structural

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34
Q

What do contractile proteins do?

A

generate force during contraction; myosin and actin

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35
Q

What do regulatory proteins do?

A

help switch the contraction process on and off

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36
Q

What do structural proteins do?

A

keep the thick and thin filaments in the proper alignment, give the myofibrils elasticity and extensibility, and link the myofibrils to the sarcolemma and extracellular matrix

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37
Q

What do motor proteins do?

A

pull various cellular structures to achieve movement by converting the chemical energy in ATP to the mechanical energy of motion

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38
Q

What 2 binding sites are located on myosin heads?

A

actin and ATP

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39
Q

What is ATPase?

A

an enzyme that hydrolyzes ATP to generate energy for muscle contraction

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40
Q

What are Z discs?

A

narrow, plate-shaped regions of dense material that separate one sarcomere from the next

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41
Q

What is the A band?

A

dark, middle part of sarcomere that extends the entire length of thick filaments and includes those parts of thin filaments that overlap thick filaments

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42
Q

What is the I band?

A

lighter, less dense area of sarcomere that contains remainder of thin filaments but no thick filaments; a Z disc passes through center of each I band

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43
Q

What is the H band?

A

narrow region in center of each A band that contains thick filaments but no thin filaments

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44
Q

What is the M line?

A

region in center of H zone that contains proteins that hold thick filaments together at center of sarcomere

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45
Q

What is actin?

A

main component of thin filaments, on each actin molecule is a myosin-binding site where a myosin head can attach

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46
Q

What are the two regulatory proteins in muscles?

A

troponin and tropomyosin

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47
Q

What is tropomyosin?

A

a component of thin filament; when skeletal muscle fiber is relaxed, tropomyosin covers myosin-binding sites on actin molecules, thereby preventing myosin from binding to actin

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48
Q

What is troponin?

A

component of thin filament; when calcium ions binds to troponin, it changes shape, this conformational change moves tropomyosin away from myosin-binding sites on actin molecules, and muscle contraction subsequently begins as myosin binds on actin

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49
Q

What is titin?

A

a structural protein that connects Z disc to M line of sarcomere, thereby helping stabilize thick filament position; it can stretch and then spring back unharmed, and thus accounts for much of the elasticity and extensibility of myofibrils

50
Q

What is α-actinin?

A

structural protein of Z discs that attaches to actin molecules of thin filaments and to titin molecules

51
Q

What is myomesin?

A

structural protein that forms M line of sarcomere; binds to titin molecules and connects adjacent thick filaments to one another

52
Q

What is nebulin?

A

structural protein that wraps around entire length of each thin filament; helps anchor thin filaments to Z discs and regulates length of thin filaments during development

53
Q

What is dystrophin?

A

structural protein that links thin filaments of sarcomere to integral membrane proteins in sarcolemma, which are attached in turn to proteins in connective tissue matrix that surrounds muscle fibers; thought to help reinforce sarcolemma and help transmit tension generated by sarcomeres to tendons

54
Q

Define skeletal muscle

A

organ made up of muscle fascicles that contain muscle fibers, blood vessels and nerves; wrapped in epimysium

55
Q

Define muscle fascicle

A

bundle of muscle fibers wrapped in perimysium

56
Q

Define muscle fiber

A

long cylindrical cell covered by endomysium and sarcolemma; contains sarcoplasm, myofibrils, many peripherally located nuclei, mitochondria, T tubules, sarcoplasmic reticulum, and terminal cisterns; has a striated appearance

57
Q

Define myofibril

A

threadlike contractile elements within sarcoplasm of muscle fiber that extend entire length of fiber; composed of filaments

58
Q

Define filaments/myofilaments

A

contractile proteins within myofibrils that are of two types: thick filaments composed of myosin and thin filaments composed of actin, tropomyosin, and troponin; sliding of thin filaments past thick filaments produces muscle shortening

59
Q

What is the sliding filament mechanism?

A

the process of skeletal muscle shortening during contraction by thick and thin filaments sliding past one another

60
Q

What is the contraction cycle?

A

repeating sequence of events that causes the filaments to slide

61
Q

What is step 1 of the contraction cycle?

A

ATP hydrolysis- myosin head hydrolyzes ATP and becomes energized and oriented

62
Q

What is step 2 of the contraction cycle?

A

attachment of myosin to actin- myosin head binds to actin, forming a cross-bridge

63
Q

What is step 3 of the contraction cycle?

A

power stroke- myosin head pivots, pulling the thin filament past the thick filament toward the center of the sarcomere

64
Q

What is step 4 of the contraction cycle?

A

detachment of myosin from actin- as myosin head binds ATP, the cross-bridge detaches from actin

65
Q

Where is calcium stored?

A

sarcoplasmic reticulum

66
Q

What are voltage-gated Ca2+ channels?

A

located in the T tubule membrane; arranged in tetrads; serve as voltage sensors that trigger the opening of the Ca2+ release channels

67
Q

What are Ca2+ release channels?

A

release calcium from the SR for muscle contraction

68
Q

What is the length-tension relationship?

A

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

69
Q

What is the neuromuscular junction (NMJ)?

A

the synapse between a somatic motor neuron and a skeletal muscle fiber; includes all synaptic end bulbs on one side of synaptic cleft, the synaptic cleft, motor end plate of muscle fiber on the other side

70
Q

synapse

A

a region where communication occurs between 2 neurons or between a neuron and a target cell

71
Q

synaptic cleft

A

a small gap that separates the 2 cells at most synapses

72
Q

neurotransmitter

A

chemical messenger that allows the cells to communicate across the gap

73
Q

axon terminal

A

end of a motor neuron

74
Q

synaptic end bulbs

A

in clusters, neural part of NMJ

75
Q

synaptic vesicles

A

membrane-enclosed sacs suspended in the cytosol within each synaptic end bulb, contains thousands of molecules of acetylcholine

76
Q

acetylcholine (ACh)

A

neurotransmitter released at the NMJ

77
Q

motor end plate

A

region of the sarcolemma opposite the synaptic end bulbs, muscular part of NMJ, contains ACh receptors

78
Q

acetylcholine receptors

A

integral transmembrane proteins to which ACh specifically binds, abundant in junctional folds

79
Q

junctional folds

A

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

80
Q

what type of channel are ACh receptors?

A

ligand-gated ion channels

81
Q

What is step 1 of generating a muscle action potential?

A

nerve impulse stimulates voltage-gated channels to open and release Ca2+, synaptic vesicles release ACh into the synaptic cleft

82
Q

What is step 2 of generating a muscle action potential?

A

ACh binds to the ACh receptor in a junctional fold, ion channel opens which allows Na+ to flow across the membrane

83
Q

What is step 3 of generating a muscle action potential?

A

inflow of Na+ makes the inside of the muscle fiber more positively charged, change in membrane potential triggers a muscle action potential which propagates along the sarcolemma into the system of T tubules, SR releases stored Ca2+ into the sarcoplasm and the muscle fiber contracts

84
Q

What 3 ways can muscle fibers produce ATP?

A

creatine phosphate, anaerobic glycolysis, and aerobic respiration

85
Q

How does creatine phosphate produce ATP?

A

formed from ATP while the muscle is relaxed, transfers a high-energy phosphate group to ADP, forming ATP during muscle contraction

86
Q

How long does energy produced from creatine phosphate last?

A

15 seconds

87
Q

How does anaerobic glycolysis produce ATP?

A

breakdown of muscle glycogen into glucose and production of pyruvic acid from glucose via glycolysis produce both ATP and lactic acid; because no oxygen is needed, this is an anaerobic pathway

88
Q

How does aerobic respiration produce ATP?

A

within the mitochondria, pyruvic acid, fatty acids, and amino acids are used to produce ATP via aerobic respiration, an oxygen-requiring set of reactions

89
Q

How long does the energy produced from anaerobic glycolysis last?

A

2 minutes

90
Q

How long does the energy produced from aerobic respiration last?

A

several minutes to hours

91
Q

What two ways does muscle tissue receive oxygen?

A

diffused from the blood or released from myoglobin

92
Q

What is muscle fatigue?

A

the inability of a muscle to maintain force of contraction after prolonged activity

93
Q

What are some potential causes of muscle fatigue?

A

inadequate release of calcium ions from SR, depletion of creatine phosphate, insufficient oxygen, depletion of glycogen and other nutrients, buildup of lactic acid and ADP, failure of action potentials in the motor neuron to release enough ACh

93
Q

What is oxygen debt/recovery oxygen uptake?

A

added oxygen, over and above, the resting oxygen consumption, that is taken back into the body after exercise

94
Q

frequency of stimulation

A

number of nerve impulses per second

95
Q

motor unit

A

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

96
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

97
Q

myogram

A

record of a muscle contraction

98
Q

latent period

A

brief delay between application of stimulus and the beginning of contraction

99
Q

What happens during the latent period?

A

the muscle action potential sweeps over the sarcolemma and Ca2+ is released from the SR

100
Q

What happens during the contraction period?

A

Ca2+ binds to troponin, myosin-binding sites on actin are exposed, cross-bridges form, peak tension develops in the muscle fiber

101
Q

What happens during the relaxation period?

A

Ca2+ is actively transported back into the SR, myosin-binding sites are covered by tropomyosin, myosin heads detach from actin, tension in muscle fiber decreases

102
Q

refractory period

A

a characteristic of all muscle and nerve cells where there is lost excitability

103
Q

wave summation

A

stimuli arriving at different times causes larger contractions, second contraction stronger than the first

104
Q

unfused tetanus

A

skeletal muscle fiber is stimulated between 20-30 times per second and only partially relaxes between contractions

105
Q

fused tetanus

A

skeletal muscle fiber is stimulated between 80-100 times per second and does not relax at all; a sustained contraction in which individual twitches cannot be detected

106
Q

motor unit recruitment

A

process in which the number of active motor units increases; weakest motor units recruited first, with progressively stronger motor units added if the task requires more force

107
Q

muscle tone

A

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

108
Q

flaccid

A

state of limpness in which muscle tone is lost

109
Q

isotonic contraction

A

the tension developed in the muscle remains almost constant while the muscle changes its length

110
Q

concentric isotonic conctraction

A

if the tension generated is great enough to overcome, the resistance of the object to be moved, the muscle shortens and pulls on another structure such as a tendon, to produce movement and reduce the angle at a joint

111
Q

eccentric isotonic contraction

A

the tension exerted by the myosin cross-bridges resists movement of a load and slows the lengthening process

112
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 in length

113
Q

mesoderm

A

what the muscles of the body are derived from

114
Q

somites

A

columns of mesoderm that have undergone segmentation into a series of cube-shaped structures

115
Q

myotome

A

forms the skeletal muscles of the trunk and limbs

116
Q

dermatomal mesenchyme

A

forms the connective tissues including the dermis of the skin and subcutaneous tissue

117
Q

schlerotome

A

gives rise to the vertebrae and ribs

118
Q

intercalated discs

A

irregular transverse thickenings of the sarcolemma that connect the ends of cardiac muscle fibers to one another

119
Q

hypertrophy

A

enlargement of existing cells

120
Q

hyperplasia

A

increase in the number of fibers

anatomy (22 decks)

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