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Flashcards in muscular system Deck (198):
1

Name 2 root words for muscle.

myo and sarco

2

the study of muscles

myology

3

a skeletal muscle cell

myofiber or muscle fiber

4

under conscious control

voluntary

5

not under conscious control

involuntary

6

striped or banded in appearance

striated

7

long, striated, multinucleate, voluntary cylinders

skeletal muscle

8

short, branched, striated, uni-nucleate and involuntary muscle

cardiac muscle

9

fusiform, uni-nucleate, non-striated, and involuntary

smooth muscle

10

4 characteristics of muscle tissue

1. excitability - can react to stimuli
2. elasticity - snaps back to shape
3. extensibility - can stretch
4. contractility - can shorten

11

5 functions of muscle

1. cause movement
2. produce body heat
3. protect internal organs
4. guard entrances and exits to the body
5. give posture and body position and stabilize joints

12

Why do muscles need a good nerve and blood supply?

nerves tell it to contract
blood brings in food and oxygen and carries away waste

13

outer CT covering, over the entire muscle

epimysium

14

covering over muscle fascicles

perimysium

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covering over individual muscle fibers

endomysium

16

What do the epimysium, perimysium and endomysium form at the ends of a muscle?

tendon or aponeurosis

17

What is the difference between a tendon and an aponeurosis?

tendon - cord - Achilles (calcaneal)
aponeurosis - sheet - lumbar, galea

18

What travels throughout the perimysium?

blood supply and nerves

19

where a muscle starts, usually on the less movable bone

origin

20

where a muscle ends, usually on the more movable bone

insertion

21

what a muscle does

action

22

the nerve supply to a muscle

innervation

23

when the epimysium is fused to the periosteum

direct attachment

24

Which is more common, an indirect or a direct attachment? Why?

indirect - Most muscles have a tendon or aponeurosis because there is less bulk, and it can pass over joints more easily.

25

muscle cell membrane

sarcolemma

26

muscle cell cytoplasm

sarcolemma

27

muscle ER

SR - sarcoplasmic reticulum

28

contractile organelle in a muscle - cylinders of thick and thin myofilaments

myofibril

29

contractile unit of a myofibril - from z line to z line

sarcomere

30

the stored glycogen granules in a muscle

glycosomes

31

pigment in muscle that stores oxygen

myoglobin

32

How many myofibrils are in a single muscle fiber?

hundreds to thousands - 80% of fiber volume

33

the lighter region of the striations - made of thin fibers

I band

34

the darker region of striations - made of the length of the thick fibers

A band

35

holds actin threads together and forms a sarcomere

z lines

36

holds thick fibers together at middle of sarcomere

m line

37

the region where there are both thick and thin fibers

zone of overlap

38

the regulatory proteins on the actin

troponin and tropomyosin

39

the protein thick fibers are made up of

myosin

40

the protein that most of the thin filament is made up of

actin

41

the myosin heads form this when they connect to the actin

cross bridges

42

the place on the actin where the myosin head attaches

active site (binding site)

43

the lighter region in the middle of the A band, where there is no overlap

H zone

44

ATPase is what - Where is it found in muscle?

enzyme that breaks down ATP - found on the myosin head

45

the elastic protein filament that extends from the thick filament to the Z line and helps it spring back to place

titin

46

the end sacs of the SR that hold calcium

terminal cisternae (cistern)

47

the protrusions of the sarcolemma into the interior of the muscle fiber

t-tubules

48

2 terminal cisternae and 1 t-tubule

triad

49

What does the triad correspond to on the sarcomere? Why is this location important?

zone of overlap - so calcium is released to the correct location

50

a structural protein that links the thin filaments to the sarcolemma

dystrophin

51

the model of muscle contraction

sliding filament theory

52

do the actin or myosin molecules shorten when a muscle contracts? Explain.

No, they slide past one another as the myosin heads grab and pull on the actin threads. The actin slides toward the M line.

53

a nerve impulse

action potential

54

a place where a nerve and muscle meet

neuromuscular or myoneural junction

55

neurons that stimulate muscles

motor neurons

56

neurons that take information to the CNS

sensory neurons

57

the gap between a neuron and a muscle or another neuron

synaptic cleft

58

the sacs of chemicals in a synaptic knob

synaptic vesicles

59

the chemicals that send nerve messages across the synapse

neurotransmitters

60

the neurotransmitter in a neuromuscular junction

ACh - acetylcholine

61

what are the folds in the motor end plate, and what is their purpose

junctional folds - increase SA - more receptors

62

the cell membrane before the synapse

presynaptic membrane

63

the cell membrane after the synapse

postsynaptic

64

the sarcolemma of a muscle at the point of the synapse

motor end plate

65

the enzyme that breaks down ACh

AChE - acetylcholinesterase

66

What is the importance of AChE?

allow the message to stop

67

food poisoning that prevents the release of ACh causing paralysis

botulism

68

an autoimmune disease that attacks the ACh receptors causing paralysis

MG - myasthenia gravis

69

the electrical condition of the motor end plate before it receives the message

polarized - having 2 opposite charges on different sides of the membrane

70

What happens to the sarcolemma's polarity as it sends the message?

depolarized - loses its charge difference

71

What has to happen to the sarcolemma's charge before it can send another message?

repolarized - get the opposite charges again

72

How is the membrane repolarized?

sodium-potassium pump

73

local depolarization

end plate potential

74

the period of time during which the membrane cannot respond to another stimulus because it isn't completely repolarized

refractory period

75

What are the two types of refractory period, and how are they different?

1. absolute refractory period - absolutely no response no matter how strong the stimulus
2. relative refractory period - will respond if stimulus is strong enough

76

Why does cardiac muscle need a longer refractory period?

We want the heart to fill with blood before contracting again.

77

stiffness after death

rigor mortis

78

What causes rigor mortis?

no ATP or energy so cross bridges don't release

79

When does rigor mortis finally stop?

after myofilaments start to decay

80

When does rigor mortis start? When is its peak time? When does it typically cease?

starts - 3 to 4 hours after death
peak - 12 hours after death
stops 48 to 60 hours after death

81

Other than time, what affects rigor mortis?

environmental conditions like temperature

82

the force exerted by a contracting muscle

muscle tension

83

the opposing force to muscle contraction

load

84

when the load is not moved but the tension increases

isometric

85

when the load is moved

isotonic

86

one motor neuron and all its fibers

motor unit

87

How do muscles generate more power?

more motor units are recruited

88

Compare motor units in the eye and leg.

eye - small and precise
leg - large and powerful

89

a graph of a single contraction/relaxation sequence in a muscle - a muscle twitch

myogram

90

the period at the beginning of the myogram where there is not a response yet

latent period

91

the upward tracing as tension increases

contraction phase

92

the downward tracing as tension decreases

relaxation

93

as the stimuli come a little faster and the next twitch is higher

wave summation

94

when the muscle reaches maximum tension with some relaxation

incomplete tetanus

95

when the stimuli come so fast that no relaxation is seen in the graph

complete tetanus

96

All actual muscle activity is what kind of myogram?

complete tetanus

97

when our muscles can respond to different needs like lifting something light or something heavy

graded muscle response

98

How can we get a graded muscle response? 2 ways

1. stronger stimulus
2. higher frequency stimulus

99

the minimum stimulus necessary to cause a response - 2 terms

1. threshold
2. liminal

100

a stimulus below that necessary to cause a response - 2 terms

1. subthreshold
2. subliminal

101

getting more motor units involved - 2 terms

1. recruitment
2. multiple motor unit summation

102

the strongest stimulus that can increase contractile force

maximal stimulus

103

How does recruitment progress?

smallest motor units first - largest and least reactive last

104

usually not all motor units are working at the same time so others can rest and take over when needed

asynchronous

105

when some muscle fibers are contracted at any given time

muscle tone

106

What are the 2 biggest advantages of having muscle tone?

1. higher metabolism - burn food more
2. more stability for joints - muscles are ready to contract if needed

107

What are the two parts of an isotonic contraction, and how are they different?

1. concentric - shortening
2. eccentric - lengthening - stronger

108

usable cellular energy

ATP - adenosine triphosphate

109

Where is the energy stored in ATP, and how does the cell get the energy?

phosphate bonds - break bonds

110

a chemical that can store phosphate to phosphorylate ADP and make ATP

CP - creatine phosphate

111

How long can stored energy in muscles last?

14-16 seconds

112

What does the body have to do after the muscles use all their stored energy?

make more by respiration

113

What are the 2 kinds of respiration, and how do they compare?

1. aerobic - more efficient (with oxygen) - makes more energy and less waste
2. anaerobic - less efficient (without oxygen) - makes less energy and more waste

114

What are the end products of aerobic respiration, and what happens to them?

CO2 and H2O - exhale them

115

What are the end products of anaerobic respiration, and what happens to them?

lactic acid - circulates in blood until it can be removed - makes muscles tired and sore

116

another name for anaerobic respiration

glycolysis

117

What does glycolysis literally mean, and how much energy is produced?

breakdown of glucose into 2 pyruvic acids - 4 ATP - 2 are invested so a net of 2ATP per glucose

118

What are the advantages of anaerobic respiration?

starts quickly and can progress faster - also when there is no oxygen present

119

How long can anaerobic exercises last?

a minute

120

What organelle does aerobic respiration? How much ATP is generated?

mitochondrion - 32 ATP per glucose

121

the length of time a muscle can use aerobic respiration

aerobic endurance - anaerobic threshold

122

the main muscle that causes a movement - 2 terms

1. agonist
2. prime mover

123

the muscle that works opposite the agonist

antagonist

124

a muscle that helps with a motion but is not the main muscle

synergist

125

a muscle that stabilizes a joint to allow another to work

fixator

126

Give 2 examples of antagonistic muscle pairs

1. biceps and triceps
2. quadriceps and hamstrings

127

Give 7 ways muscles are named.

1. location
2. shape
3. relative size
4. direction of fibers
5. number of origins
6. location of attachment
7. action

128

the inability to contract with sufficient neural stimulation

fatigue

129

What has to happen for a muscle to recover from activity?

1. release heat
2. pay back oxygen debt by breathing heavily
3. replace energy reserves - ATP, glycogen, CP
`

130

when a muscle loses mass due to inactivity

atrophy

131

when a muscle gains mass due to use

hypertrophy

132

force generated by cross bridges

internal tension

133

force transferred from cross bridges to load

external tension

134

how much overlap determines the strength of a contraction - ideal is 80-100% of resting length
- can't contract with too much or too little overlap

length-tension relationship

135

immature muscle cells

myoblasts

136

what happens to myoblasts

fuse to make a myotube

137

what do we call myoblasts that don't fuse, and for what are they used

satellite cells - repair of damaged muscle

138

What happens to satellite over time - so how is muscle repaired?

are used up - get fibrosis instead of regeneration

139

In what direction does muscle develop?

head to toe
proximal to distal

140

Who has more muscle mass, men or women and why?

men - due to testosterone which stimulates muscle development

141

synthetic male sex hormones

anabolic steroids

142

world's most common genetic disorder, affects muscle - muscle first enlarges due to fat and then atrophies

muscular dystrophy

143

the most common form of MD - what causes it

Duchenne muscular dystrophy - lack of the protein dystrophin

144

What is the most common cause of death in muscular dystrophy?

respiratory failure

145

gradual loss of muscle mass with age

sarcopenia

146

a condition that limits blood flow to the muscles of the appendages (particularly the legs) causing pain during walking

intermittent claudidication

147

What should be done first for minor muscle injuries?

RICE - rest, ice, compression, elevation

148

a sudden, involuntary muscle twitch

spasm

149

a pulled muscle with excessive stretching and some torn fibers due to overuse

strain

150

inflammation of muscle

myositis

151

muscle pain

myalgia

152

disease of muscle

myopathy

153

How are muscle fibers classified? 2 ways

1. speed of contraction - size of fiber (fast and slow twitch)
2. how they make energy (glycolytic and oxidative)

154

How do glycolytic fibers get energy?

glycolysis - anaerobic

155

How do oxidative fibers get their energy?

aerobic respiration - with oxygen

156

fast twitch fiber scientific name

slow oxidative

157

slow twitch fiber scientific name

fast glycolytic

158

intermediate fiber scientific name

fast oxidative

159

What are fast twitch fibers best at?

endurance

160

What are slow twitch fibers best at?

power - sprints and jumps

161

What is the advantage of intermediate fibers?

can be trained to get better at both power and endurance

162

which fibers are thin because they don't have a lot of stored energy or many myofibrils but with many mitochondria and good blood supply

slow oxidative - slow twitch

163

which fibers are thick with lots of stored energy and myofibrils but without a good blood supply and without many mitochondria

fast glycolytic - fast twitch

164

Which fiber type would be called red meat? Why

slow - good blood supply

165

Which fiber type would be called white meat? Why?

fast - poor blood supply

166

Where do the characteristics of the fast oxidative fibers fit in with the other two?

intermediate - pink, medium amounts of most everything

167

What determines the predominate fiber type?

genetics - interspersed throughout the muscle
- but within a motor unit, they are all the same

168

How does load affect contraction speed?

greater load slows contraction speed

169

a disease of chronic inflammation of muscles, its CT and tendons

fibromyalgia or fibromyositis

170

protrusion of an organ through a body cavity wall

hernia

171

a non-sex linked type of MD, less common than Duchenne MD

myotonic dystrophy

172

a disease of sustained, powerful muscular contractions caused by a toxin released from bacteria

tetanus

173

Why are people more likely to get tetanus from a puncture wound?

doesn't bleed and flush out the wound

174

What is another name for the disease tetanus and why?

lockjaw - jaw muscles are often affected first

175

What does aerobic exercise do to promote endurance?

more capillaries, more mitochondria, more myoglobin

176

What kind of muscle activity promotes hypertrophy?

resistance exercises like weightlifting

177

What happens to a muscle to make a muscle hypertrophy?

larger fibers rather than more fibers - more CT, splitting of fibers

178

What are 5 differences between skeletal and smooth muscle?

1. less CT
2. different neuromuscular junction - has varicosities and diffuse junctions or swellings instead of the classic bulb...
3. less developed sarcoplasmic reticulum
4. no striations - no sarcomeres
5. have a third kind of myofilament called an intermediate filament which attaches to the sarcolemma at regular intervals by something called a dense body

179

What are the two layers of smooth muscle?

1. longitudinal layer - makes lumen shorter
2. circular layer - constricts lumen

180

the wavelike contractions of smooth muscle that move food through the digestive tract - alternating longitudinal and circular contraction

peristalsis

181

What is different about the thick filaments of smooth muscle?

fewer and with heads along the entire length

182

What is different about the regulation and calcium binding site of smooth muscle?

has a chemical called calmodulin instead of troponin

183

What is the major difference in the arrangement of thick and thin fibers in smooth muscle?

diagonal so they twist when they contract

184

Why are smooth muscle fibers synchronized?

gap junctions allow transmission from fiber to fiber

185

What is the purpose of pacemaker cells?

self-excitatory cells that set the rhythm but can be affected by neural stimulation or hormones

186

a circular muscle that opens or closes a hole

sphincter

187

examples of sphincters

orbicularis oris and orbicularis oculi

188

muscles with a broad origin and a tendon insertion

convergent

189

example of convergent muscles

pectoralis major

190

muscles whose fibers run side by side - what is the advantage?

parallel - most movement

191

example of parallel muscles

sartorius

192

muscles whose fibers come in on an oblique angle to the tendon - like a feather

pennate

193

pennate on 1 side, 2 sides, many sides - what is the advantage?

unipennate, bipennate, multipennate - most power - especially multipennate

194

muscles with a big belly and a torpedo shape

fusiform

195

what provides leverage for muscles?

bones

196

what is the fulcrum for the muscles?

joints

197

What are the 3 types of lever systems? Give an example for each.

1st - seasaws and scissors
2nd - wheelbarrow
3rd - tweezers

198

most muscles in the body are what type of lever?

3rd class lever