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Anatomy and Physiology 210 > Chapter 10: Muscle Tissue > Flashcards

Chapter 10: Muscle Tissue Flashcards

1
Q

Functions of skeletal muscle

A
  • move the body
  • maintain posture
  • protect and support
  • regulate elimination of materials
  • produce heat
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2
Q

Characteristics of skeletal muscle

A
  • excitability
  • conductivity
  • contractility
  • extensibility
  • elasticity
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3
Q

Organ

A

two or more types of tissue that work together to perform a specific function

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4
Q

Skeletal muscle

A

is an organ composed of muscle fibers, connective tissue layers, blood vessels, and nerves

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5
Q

3 layers of connective tissue layers of wrapping of a skeletal muscle

A

1- epimysium
2- perimysium
3- endomysium

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6
Q

Epimysium

A

dense irregular connective tissue wraps whole muscle

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7
Q

Perimysium

A

dense irregular connective tissue wraps fascicle; many blood vessels/nerves

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8
Q

Endomysium

A

areolar connective tissue wraps individual fiber; electrical insulation, capillary support, binding of neighboring cells

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9
Q

Tendon

A

cordlike structure of dense regular connective tissue

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10
Q

Aponeurosis

A

flattened sheet of dense irregular connective tissue

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11
Q

Deep fascia

A

separates individual muscles

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12
Q

Superficial fascia

A

separates muscles from skin

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13
Q

Know the structural organization of skeletal muscle

A
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14
Q

Is skeletal muscle vascularized?

A

yes, highly

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15
Q

Is skeletal muscle innervated? If so, by what?

A

yes, by somatic motor neurons

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16
Q

Somatic motor neurons

A

extend from the brain and spinal cord to skeletal muscle fibers

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17
Q

Axon

A

nerve fiber

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18
Q

Sarcoplasm

A

cytoplasm in skeletal muscle fibers

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19
Q

Multinucleated

A

multiple nuclei

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20
Q

Myoblasts

A

groups of embryonic muscle cells that fuse to form single skeletal muscle fibers during development

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21
Q

Satellite cells

A

adult stem cells

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22
Q

Know the development of skeletal muscle

A
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23
Q

Structure and organization of a skeletal muscle fiber

A
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24
Q

Sarcolemma

A

plasma membrane of a skeletal muscle fiber

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25
Q

T-tubules (transverse tubules)

A

deep invaginations within the sarcolemma that extend into the skeletal muscle fiber as a network of narrow, membranous tubules to the sarcoplasmic reticulum

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26
Q

Myofibrils

A

protein myofilaments surrounded by sarcoplasmic reticulum and extend the length of muscle fiber

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27
Q

Sarcoplasmic reticulum

A

an internal membrane complex that is similar to smooth ER in other cells; contains calcium pumps that release Ca2+ into the sarcoplasm

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28
Q

Terminal cisternae

A

enlarged calcium ion reservoirs

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29
Q

Triad

A

2 cisternae with a T-tubule in between

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30
Q

Myofilaments

A

contractile proteins within myofibrils;
2 types:
1- thick filaments
2- thin filaments

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31
Q

Thick filaments

A

consist of bundles of ONLY myosin protein strands; each strand with a globular head and elongated tail

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32
Q

Thin filaments

A

twisted strands of actin protein; F-actin (filamentous) composed of G-actin (globular); G-actin has a myosin binding site; tropomyosin and troponin placed along F-actin strand

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33
Q

Tropomyosin

A

short, thin, twisted filament that is a “stringlike” protein

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34
Q

Troponin

A

globular, or “ball-like”, protein attached to tropomyosin; contains the binding site for Ca2+

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35
Q

Sarcomeres

A

myofilaments arranged in repeating units

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36
Q

Z discs

A

composed of specialized proteins that are positioned perpendicular to the myofilaments and serve as anchors for the thin filaments

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37
Q

I bands

A

light-appearing regions that contain only thin filaments and Z disc; get smaller when muscle contracts (can disappear with maximal contraction)

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38
Q

A band

A

a dark-appearing region that contains thick filaments and overlapping thin filaments; contains H zone and M line; makes up general region of sarcomere

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39
Q

H zone

A

central portion of A band; only thick filaments; disappears with maximal muscle contraction

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40
Q

M line

A

middle of H zone and centermost region of A band; attachment site for thick filaments

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41
Q

Molecular structure of thick and thin filaments

A
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42
Q

Structure of a sarcomere

A
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43
Q

Striations

A

repeating light and dark bands of the overlapping myofilaments that form unique striped patterns within the skeletal muscle fiber

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44
Q

Connectin

A

stabilizes thick filaments from Z disc to M line; has spring like properties (passive tension)

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45
Q

Dystrophin

A

links internal myofilament proteins to external proteins; anchors some myofibrils to sarcolemma proteins; abnormalities of this protein cause muscular dystrophy

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46
Q

Myoglobin

A

within cells allow storage of oxygen used for aerobic ATP production; unique to muscle tissue; binds oxygen when muscle is at rest

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47
Q

Glycogen

A

stored for when fuel is needed quickly (storage form of glucose)

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48
Q

Creatinine phosphate

A

can quickly give up its phosphate group to help replenish ATP supply; unique to skeletal muscle tissue; anaerobic

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49
Q

Motor unit

A

a motor neuron and all the muscle fibers it controls

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50
Q

Neuromuscular junction

A

location where motor neuron innervates muscle; site of communication between motor neuron and motor end plate of muscle

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51
Q

Structure of a motor unit

A
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52
Q

Structure and organization of a neuromuscular junction

A
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53
Q

Smaller motor units

A

have less than five muscle fibers and allow for precise control of smaller force output

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54
Q

Large motor units

A

have thousands of muscle fibers and allow for production of large amounts of force but not precise control

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54
Q

Synaptic knob

A

houses synaptic vesicles with acetylcholine (ACh); calcium pumps establish calcium gradient, with more outside the neuron

55
Q

Motor end plate

A

specialized region of sarcolemma with numerous folds; has many ACh receptors which are opened by binding of ACh and allow Na+ entry and K+ exit

56
Q

Synaptic cleft

A

separates the synaptic knob from the motor end plate; acetylcholinesterase (AChE) resides here and is an enzyme that breaks down ACh molecules

57
Q

Muscle fibers exhibiting RMP

A

RMP inside the cell is -90mV compared to fluid outside the cell; threshold potential is -65mV

58
Q

Skeletal muscle fiber at rest

A
59
Q

End-plate potential (EPP)

A

the minimum voltage change (or threshold) in the motor end plate that can trigger opening of voltage-gated channels in the sarcolemma to initiate an action potential

60
Q

Excitation of a skeletal muscle

A

1- binding of ACh at the motor end plate
2- excitation-contraction coupling
3- sarcomere: cross-bridge cycling

61
Q

Events in skeletal muscle contraction

A
62
Q

Neuromuscular junction: excitation of a skeletal muscle tissue

A
63
Q

Sarcolemma, t-tubules, and sarcoplasmic reticulum: excitation-contraction coupling

A
64
Q

Sarcomere: cross-bridge cycling

A
65
Q

Depolarization

A

the reversal in polarity at the sarcolemma (- to +)

66
Q

Repolarization

A

changes the membrane potential from positive to negative

67
Q

Refractory period

A

the muscle cannot be stimulated

68
Q

Crossbridge cycling

A

multiple repetitions to attach, pull, release, and reset lead to fully contracted sarcomere

69
Q

Power stroke

A

when the myosin head swivels

70
Q

Tetanus

A

overstimulation of a muscle that leads to spastic paralysis

71
Q

Botulism

A

muscular paralysis caused by a toxin that’s ingested

72
Q

Sarcomere shortening

A
73
Q

3 ways to generate additional ATP in skeletal muscle

A

1- creatine phosphate
2- glycolysis
3- aerobic cellular respiration

74
Q

Creatine phosphate
(Phosphagen System)

A
  • unique to skeletal muscles
  • high-energy bond found between creatine and phosphate
  • phosphate can be transferred to ADP to form ATP
    -catalyzed by creatine kinase
75
Q

Glycolysis (Anaerobic Cellular Respiration)

A
  • occurs in cytosol
  • does not require oxygen
  • glucose is converted to 2 pyruvate molecules
  • 2 ATP released per glucose molecule
76
Q

Aerobic Cellular Respiration

A
  • makes the most ATP supply
  • requires oxygen
  • occurs within mitochondria
  • pyruvate (from Glycolysis) broken down
  • produces approximately 34 ATP
  • triglycerides and amino acids can also be used as fuel to produce ATP
77
Q

Metabolic processes for generating ATP

A
78
Q

Lactate formation

A

pyruvate converted to lactate when O2 is low; lactate can be used as fuel by skeletal muscle fiber

79
Q

Utilization of energy sources

A
80
Q

Oxygen debt

A

amount of additional O2 needed after exercise to restore pre-exercise conditions

81
Q

Additional oxygen required to

A
  • replace O2 on hemoglobin and myoglobin
  • replenish glycogen
  • replenish ATP and creatine phosphate
  • convert lactic acid back to glucose
82
Q

Skeletal muscle fibers classified based on:

A
  • type of contraction generated
  • means for supplying ATP
83
Q

Type of contraction generated

A
  • power: related to the diameter of muscle fiber
  • speed and duration
  • fast-twitch fibers are more powerful and have quicker and briefer contractions than slow-twitch fibers
84
Q

Speed and duration related to

A
  • type of myosin ATPase
  • quickness of action potential propagation
  • quickness of Ca2+ reuptake by sarcoplasmic reticulum
85
Q

Skeletal fibers classified based on means for supplying ATP

A
  • oxidative fibers (fatigue resistant)
  • glycolytic fibers (fatigable)
86
Q

Oxidative fibers

A

use aerobic cellular respiration; have extensive capillaries, many mitochondria, lots of myoglobin

87
Q

Glycolytic fibers

A

use anaerobic cellular respiration; have fewer capillaries, fewer mitochondria, fewer myoglobin, and large glycogen reserves

88
Q

3 types of skeletal muscle fibers

A

1- slow oxidative (SO) fibers (type I)
2- fast oxidative (FO) fibers (type IIa, intermediate)
3- fast glycolytic (FG) fibers (type IIx, fast anaerobic)

89
Q

Slow oxidative (SO) fibers

A
  • contractions= slower and less powerful
  • high endurance since ATP supplied aerobically
  • slender, red in color due to myoglobin
90
Q

Fast oxidative (FO) fibers

A
  • contractions= fast and powerful
  • primarily aerobic respiration
  • intermediate size, light red color
91
Q

Fast glycolytic (FG) fibers

A
  • contractions= fast and powerful
  • contractions are brief, as ATP production is primarily anaerobic
  • thick, white in color due to lack of myoglobin
  • most common type
92
Q

Hand muscles

A

have high percentage of fast glycolytic fibers for quickness

93
Q

Sprinters

A

have higher percentage of fast glycolytic fibers (fatigable)

94
Q

Back muscles

A

have high percentage of slow oxidative fibers to continually maintain postural support

95
Q

Long-distance runners

A

have higher proportion of slow-oxidative fibers (endurance) in legs

96
Q

Muscle tension

A

force generated when a muscle is stimulated to contract (twitch)

97
Q

Muscle twitch

A

a single, brief contraction from a single stimulus

98
Q

Threshold

A

the minimum voltage needed to stimulate the skeletal muscle to generate a twitch

99
Q

Latent period

A

time after stimulus, but before contraction begins; no change in tension

100
Q

Contraction period

A

time when tension is increasing; begins during power strokes as thick pulls thin filaments

101
Q

Relaxation period

A

time when tension is decreasing; begins with release of cross-bridges; generally, lasts a little longer than a contraction period

102
Q

Muscle twitch

A
103
Q

Recruitment (Multiple Motor Unit Summation)

A
  • muscle is stimulated repeatedly
  • as voltage increases, more units are recruited to contract
  • muscles can exhibit varying degrees of force
  • above a certain voltage, all units are recruited and maximum contraction occurs
  • a muscle relaxes completely before the next contraction
104
Q

Treppe

A

increase in contraction strength

105
Q

Wave summation

A

occurs when stimulations are delivered to a muscle fiber faster than it is able to completely relax

if stimulus frequency is set at about 20 per second,
- relaxation is not completed between twitches
- contractile forces add up to produce higher tensions

106
Q

Incomplete tetany

A

if frequency is increased further; tension increases and twitches overlap

107
Q

Tetany

A

if frequency is increased further still; tension is a smooth line, without relaxation; high frequency stimuli lead to fatigue

108
Q

Fatigue

A

no tension production

109
Q

Skeletal muscle response to change in stimulus intensity

A
110
Q

Skeletal muscle response to change in stimulus frequency

A
111
Q

Muscle tone

A

the amount of tension in muscle

112
Q

Resting muscle tone

A

random contraction of small numbers of motor units causes the skeletal muscle to develop tension

113
Q

Isometric contraction

A

although tension increases (force), it’s still less than the resistance (weight); muscle length stays the same

114
Q

Isotonic contraction

A

when skeletal muscle tension results in movement of the muscle; the tone of the muscle remains the same but the length changes

115
Q

Isometric vs. Isotonic contraction

A
116
Q

Fiber at shortened length (contracted) generates

A

weaker force; filament movement is limited (already close to Z disc)

117
Q

Fiber at resting length generates

A

maximum contractile force; optimal overlap of thick and thin filaments

118
Q

Fiber at extended length (stretched) generates

A

weaker force; minimal thick and thin filaments overlap for cross-bridge formation

119
Q

Concentric contraction

A

the shortening of muscle length

120
Q

Eccentric contraction

A

lengthening of muscle

121
Q

Muscle length and tension relationship during muscle contraction

A
122
Q

Length-tension curve

A
123
Q

Maximizing force of contraction

A
124
Q

Muscle fatigue

A
  • reduced ability to produce muscle tension
  • primarily caused by a decrease in glycogen stores during prolonged exercise
  • insufficient Ca2+ to enter synaptic knob
  • decreased number of synaptic vesicles
  • altered ion concentrations impair action potential conduction and Ca2+ release from sarcoplasmic reticulum
  • less Ca2+ available for troponin
125
Q

Changes in muscle from a sustained exercise program

A
  • endurance exercise leads to better ATP production
  • resistance exercise leads to hypertrophy; limited amount of hyperplasia (increased number of fibers)
126
Q

Changes in muscle from lack of exercise

A

atrophy= decrease in size due to lack of use

127
Q

Fibrosis

A

muscle mass is often replaced by adipose connective tissue and dense regular connective tissue; decreased flexibility

128
Q

Loss of muscle mass with age

A
  • slow loss begins in a person’s mid-30s due to a decrease in activity
  • decreased size, power, and endurance of skeletal muscle
  • loss in fiber number and diameter
    decreased oxygen storage capacity
  • decreased circulatory supply to muscles with exercise
129
Q

Cardiac muscle tissue

A
  • individual muscle cells arranged in thick bundles within the heart wall
  • has one or two nuclei
  • have large numbers of mitochondria and use aerobic respiration
  • autorhythmic pacemaker that stimulates cardiac muscle cells
  • branching cells
130
Q

Intercalated discs

A

individual cells are joined to adjacent muscle cells at these specialized junctions

131
Q

Smooth muscle tissue

A

found in organs of many body systems:
- cardiovascular system= blood vessels
- respiratory system= bronchioles
- digestive system= small & large intestine
- urinary system= ureters
- female reproductive system= uterus
- others= iris of the eye

132
Q

Smooth muscle cell shape

A
  • fusiform
  • central nucleus
  • small
133
Q

Smooth muscle cell characteristics

A
  • sarcolemma with various types of Ca2+ channels
  • transverse tubules absent
  • sarcoplasmic reticulum sparse
134
Q

Smooth muscle arrangement of anchoring proteins and contractile proteins

A
  • dense bodies
  • dense plaques

Anatomy and Physiology 210 (13 decks)

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