Muscular System Flashcards

1
Q

Function of Muscles (3)

A
  1. power locomotion
  2. produce heat
  3. produce electricity
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2
Q

3 types of muscle classification:

A
  1. red vs. white
  2. tonic vs. twitch
  3. skeletal vs. cardiac vs. smooth
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3
Q

What is the difference between red vs white muscles?

A

metabolism

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4
Q

Describe red (dark) meat

A
  1. resistant to fatigue (endurance)
  2. high mitochondria
  3. highly vascularized
  4. lots of myoglobin
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5
Q

Describe myoglobin

A
  1. carries oxygen to muscle tissues
  2. has 1 protein subunit & is quaternary in structure
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6
Q

Describe white meat

A
  1. fatigues easily
  2. less mitochondria
  3. less vascularization
  4. less of myoglobin
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7
Q

Tonic fibers:

A
  1. slow contraction & low force (resist fatigue)
  2. common in reptiles and amphibians -
  3. rare in mammals
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8
Q

Twitch fibers:

A
  1. fast contraction & high force (fatigue easily)
  2. common in mammals
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9
Q

Location of tonic fibers in mammals

A
  1. eye muscles
  2. middle ear mucles
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10
Q

Types of twitch fibers (3)

A
  1. Type I - slow-twitch oxidative fiber
  2. Type IIa - fast-twitch oxidative
  3. Type IIb - fast-twitch glycolytic
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11
Q

How do the twitch fiber types differ?

A

myosin isoform

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12
Q

Oxidative vs. glycolytic :

A

oxidative can do phosphorylation & electron transport chain because they have mitochondria vs. glycolytic must use glycolysis since there are no mitochondria

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13
Q

Oxidation vs. reduction

A

oxidation is lost (lose electron) vs. reduction is gained (gain electron)

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14
Q

Glycolysis vs. krebs vs. ETC

A

Glycolysis - occurs in cytoplasm - 2 net ATP ( no O2 needed)
Krebs - occurs in mitochondria - 2 net ATP (needs O2)
ETC - occurs in mitochondria w/ NADH/FADH2 - 34 net ATP (needs O2)

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15
Q

What is carb loading?

A

build-up glycogen stores in liver & skeletal muscles for quick easy access to energy (prior to marathon etc.)

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16
Q

Type I

A

Slow-twitch oxidative fiber
1. does not stop at glycolysis
2. lots of mitochondria
3. endurance
4. reddish color
5. many capillaries
6. little glycogen
7. high myoglobin

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17
Q

Type IIb

A

Fast-twitch glycolytic
1. glycolysis only
2. power & quickness not endurance
3. few mitochondria
4. few capillaries
5. high glycogen
6. low myoglobin

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18
Q

Type IIa

A

Fast-twitch oxidative
1. hybrid of other 2 (not very common)
2. contract fast, resist fatigue
- ex. someone who trains for the Tour de France

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19
Q

Marathon training alters fiber composition. What changes would occur?

A

Increase in Type I (slow-twitch oxidative) and Increase in vascularization

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20
Q

What are the 3 types of muscle fibers?

A
  1. cardiac
  2. skeletal
  3. smooth
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21
Q

Skeletal muscle fiber features (5)

A
  1. locomotory muscles
  2. voluntary
  3. striated
  4. multinucleate
  5. many mitochondria
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22
Q

Cardiac muscle fiber features (10)

A
  1. short, branched fibers
  2. striated
  3. 1-2 nuclei per fiber/cell
  4. many mitochondria
  5. few neuromuscular joints
  6. fibers join at intercalated discs
  7. form thick myocardium
  8. involuntary
  9. hormonal & nervous control
  10. self-stimulation via sinoatrial node (SA node)
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23
Q

How do cardiac muscle fibers connect and communicate?

A

electrically linked by gap junctions

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24
Q

Locations of smooth muscle

A
  1. GI tract
  2. arrector pili
  3. iris of eye
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25
Q
A

intercalated disc (cardiac)

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26
Q
A

desmosome (cardiac)

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27
Q
A

intercalated disc (cardiac)

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28
Q
A

cardiac muscle (cardiac)

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29
Q
A

sarcolemma (cardiac)

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30
Q
A

nucleus (cardiac)

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31
Q
A

mitochondrion (cardiac)

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32
Q
A

gap junction

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33
Q

Smooth Muscle Features (8)

A
  1. short, almond (spindle) shaped
  2. single nucleus
  3. involuntary
  4. no striations
  5. myofilaments, but no sarcomeres
  6. myofilaments attach to dense bodies (equivalent to sarcomere)
  7. slow, sustained contraction
  8. controlled by hormones & nerves
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34
Q

What is the relative speed of smooth muscle contraction and relaxation compared to skeletal & cardiac muscle?

A

slow

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35
Q

What are the 2 contraction patterns of smooth muscle

A
  1. phasic contraction
  2. tonic contraction
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36
Q

Phasic contraction & example

A

relaxed/uncontracted is normal state (contract & then be done) - peristalsis in esophagus

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37
Q

Tonic contraction & example

A

contracted is normal state & occasionally relaxes - pyloric sphincter

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38
Q

What are the Fascia layers

A
  1. superficial fascia (hyodermis)
  2. deep fascia
  3. subserous fascia
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39
Q

Deep fascia function & structure

A

fx: wrap around muscles & keeps them separate from each other (slide no friction) - also separates muscles, nerves, and vessels
structure: dense, regular CT

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40
Q

Subserous fascia function & structure

A

fx: inside lining of body cavity (makes up coelom)
structure: areolar CT & parietal peritoneum (secretes serous fluid)

41
Q
A

tendon (DR)

42
Q
A

deep fascia

43
Q
A

fascicle

44
Q
A

muscle fiber/cell

45
Q
A

endomysium

46
Q
A

perimysium

47
Q
A

epimysium (DI)

48
Q

Parts of a muscle from biggest to smallest with membrane

A

Muscle (epimysium) -> Muscle fascicle (perimysium) -> muscle fiber (endomysium) -> myofibril (sarcolemma) -> myofilaments = actin & myosin

49
Q

Myofibril components (4)

A
  1. sacrolemma =
50
Q

Myofibril components (4)

A
  1. sarcolemma = plasma membrane
  2. sarcoplasm = cytoplasm
  3. sarcoplasmic reticulum = Smooth ER
  4. t-tubule (transverse) = continuous with sarcolemma & openings through sarcolemma
51
Q

What repairs organelles and fixes the damage done to muscle fibers?

A

satellite cells

52
Q

What are the 2 myofilaments?

A
  1. thick filaments (myosin ~250 strands)
  2. thin filaments (actin - 2 helix strands)
53
Q

Define sarcomere:

A

contracting part of a myofibril (contractile unit)

54
Q

What blocks the actin head from binding, allowing the muscles to relax?

A

tropomyosin

55
Q

What’s the function of the sarcoplasmic reticulum?

A

store calcium for contraction

56
Q

Nebulin

A

helps align actin

57
Q

Z-disk

A

separates one sarcomere from the next

58
Q

M-line

A

center/middle of sarcomere - anchor

59
Q

Titin

A

provides elasticity & stabilized myosin

60
Q

H-zone

A

wide band around M-line - it changes shape - has only myosin no actin

61
Q

Relate muscle state and size of H-zone

A

muscle contracts - H zone decreases
muscle relaxes - H zone increases

62
Q

I-band

A

thin filament only

63
Q

A-band

A

has entire thick filament

64
Q

Which sarcomere regions stay the same during contraction?

A

A-band

65
Q

Which sarcomere regions decrease in length during contraction?

A

H-zone (gone), I-band (smaller)

66
Q
A

troponin

67
Q
A

actin

68
Q
A

thin filament

69
Q
A

tropomyosin

70
Q
A

myosin head

71
Q
A

thick filament

72
Q
A

Z disk

73
Q
A

M line

74
Q

Identify (blue line, green line, red circular line, purple thick band)

A

Blue - nebulin
Green - titin
Red - actin
Purple - myosin

75
Q

Which band is dark and which band is light?

A

A band is dark due to thick filament - I band is light from lack of thick filament

76
Q

Identify parts of sarcomere

A

A. M line
B. I band
C. A band
D. H zone
E. Z disk

77
Q

What stimulates muscles?

A

motor neurons

78
Q

Motor unit

A

all fibers stimulated by same motor neuron

79
Q

Neuromuscular junction

A

attachment from neuron to muscle fiber (attaches at motor end plate)

80
Q
A

A. synaptic knob
B. synaptic cleft
C. motor end plate
D. synaptic vesicles
E. sarcolemma
F. sarcoplasm
G. Acetylcholine (Ach)
H. Ach receptor
I. Acetylcholinesterase (AChE)

81
Q

Process of muscle contraction (7 steps)

A
  1. Ach released at motor end plate. Initiates an action potential down t-tubule
  2. Ca 2+ ions released from sarcoplasmic reticulum
  3. Ca 2+ bind troponin. Tropomyosin shifts exposing myosin-binding sites on actin
  4. myosin heads pivot and pull thin filament toward M line
  5. ATP binds to myosin heads, causing it to detach from actin
  6. Cycle repeats if Ca 2+ still bound to troponin and myosin binding site open on actin
  7. If AChE breaks down Ach in synaptic cleft, the impulse stops. Ca 2+ returns to SR & tropomyosin shifts to block myosin binding sites.
82
Q

Rigor Mortis

A

Ca 2+ in SR starts to release as body decomposes which causes a contraction and then they get stuck (myosin heads bound and no ATP to release them) - after awhile enough decomposition would occur to detach and relax

83
Q

Muscle relaxers action

A

blocks release of Ca2+ from SR

84
Q

Troponin Test (T-Test)

A

troponins signal heart attack- find troponins in blood that shouldn’t be there notify to the MI

85
Q

What determines force of muscular contraction?

A
  1. myosin-actin overlap in sarcomere
  2. elastic components of muscle
  3. cross-sectional area
86
Q

What is the optimal sarcomere length & overlap of actin/myosin? Why?

A

2.0-2.3 μm - because there is a perfect amount of actin to attach to myosin heads (no actin where there are no myosin heads and no myosin heads where there is no actin)

87
Q

Speed of shortening is greater in long muscles (3)?

A
  • equal time to get to 1/2 resting length
  • speed= distance/time
  • sarcomeres have additive effect on speed
88
Q

2 different types of fiber orientation

A
  1. parallel
  2. pennate
89
Q

Parallel fiber orientation:

A
  • fibers parallel to tension
  • move light load
90
Q

Pennate fiber orientation:

A
  • fibers oblique to tension
  • move heavy load
  • more fibers in a small space
91
Q

Different types of pennate orientation and examples

A

bipennate - rectus femoris
multipennate - deltoid

92
Q

What is a physiological cross section?

A

it runs perpendicular to muscle fibers - pennate increases

93
Q

Antagonistic muscles define and example

A

muscles that work against each other - biceps (flexor) vs triceps (extensor)

94
Q

Flexion

A

moves bones closer together

95
Q

Extension

A

moves bones away fromeach other

96
Q

Synergistic muscles define and example

A

both muscles have the same action but have different insertion points (biceps brachii & brachialis)

97
Q

How does exercise affect muscles (4)?

A
  1. small increase in fiber #’s (not adding more cells)
  2. increase muscle cross-sectional area (increase width)
  3. most increase. in muscle mass due to adding myofilaments (increase muscle fiber diameter)
  4. if you don’t use it you lose it
98
Q

How does aging affect muscles (3)?

A
  1. skeletal muscle fibers decrease in diameter (loss of myofibrils, myoglobin, glycogen, strength and endurance)
  2. increased thickness of connective tissue (less flexibility)
  3. speed of recovery decreases (loss of satellite cells)