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BIOL 242 Unit 2 Flashcards > Chapter 10 Vocab > Flashcards

Chapter 10 Vocab Flashcards

1
Q

Muscle tissue types

A
  • skeletal muscle
  • cardiac muscle
  • smooth muscle
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2
Q

Common properties of muscle tissue

A
  • Excitability (responsiveness)
  • Contractility (ability of cells to shorten)
  • Extensibility (stretching)
  • Elasticity (recoil)
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3
Q

Functions of skeletal muscle

A
  • Producing movement
  • Maintaining posture and body position
  • Supporting soft tissues
  • Guarding body entrances and exits
  • Maintaining body temperature
  • Storing nutrients
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4
Q

Skeletal muscles contain

A
  • Skeletal muscle tissue (primarily)
  • Connective tissues
  • Blood vessels
  • Nerves
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5
Q

Skeletal muscles have three layers of connective tissue

A
  • Epimyseium
  • Perimysium
  • Endomysium
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6
Q

Epimysium

A
  • Layer of collagen fibers that surrounds the muscle
  • Connected to deep fascia
  • Separates muscle from deep fascia
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7
Q

`Perimysium

A

Surrounds muscle fiber cells (fascicles)

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8
Q

Perimysium contains

A
  • collagen fibers
  • elastic fibers
  • blood vessels
  • nerves
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9
Q

Endomysium

A

Surrounds individual muscle cells (muscle fibers)

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10
Q

Endomysium contains

A
  • capillary networks
  • myosatellite cells (stem cells) that repair damage
  • Nerve fibers
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11
Q

Collagen fibers of epimysium, perimysium and endomysium come together at ends of muscles to form

A

tendons (bundles) or aponeurosis (sheet)

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12
Q

Skeletal muscles have extensive vascular networks that

A
  • deliver oxygen and nutrients

- remove metabolic wastes

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13
Q

Voluntary muscles

A
  • Contract only when stimulated by central nervous system

- skeletal muscles are this

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14
Q

Skeletal muscle fibers…

A
  • are enourmous compared to other cells
  • contain hundereds of nuclei (multinucleated)
  • develop by fusion of embryonic cells (myoblasts)
  • also known as striated muscle cells due to striations
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15
Q

Sarcolemma

A
  • plasma membrane of a muscle fiber
  • surrounds the sarcoplasm (cytoplasm of a muscle fiber)
  • A sudden change in membrane potential initiates a contraction
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16
Q

Transverse Tubules (T tubules)

A
  • Tubes that extend from surface of muscle fiber deep into sarcoplasm
  • Transmit action potentials from sarcolemma into cell interior
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17
Q

Sarcoplasmic Reticulum (SR)

A
  • Tubular network surrounding each myofibril
  • similar to smooth ER
  • Forms chambers that attach to T tubules
  • Specialized for storage and release of calcium ions
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18
Q

Terminal Cisternae

A

Chambers that attach to T tubules

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19
Q

Triad

A

two terminal cisternae plus a T tubule

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20
Q

Calsequestrin

A

Binds calcium so that more can come in

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21
Q

Myofibrils

A
  • Lengthwise subdivions within a muscle fiber
  • Responsible for muscle contraction
  • made of bundles of protein filaments (myofilaments)
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22
Q

Myofilaments

A

Protein filaments that bundle up to make myofibril

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23
Q

Two types of myofilaments

A

Thin filaments: Composed of actin

Thick filaments: composed of myosin

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24
Q

Sarcomeres

A
  • smallest functional units of a muscle fiber

- interaction between filaments produce contraction

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25
Q

A bands

A

Dark bands part of striated filament of sarcomere

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26
Q

I bands

A

light bands part of striated filament of sarcomere. Contains thin filaments but not thick filaments

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27
Q

M line

A

center of A band. Proteins stabilize positions of thick filaments

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28
Q

H bands

A

On either side of M line. Has thick filaments but no thin filaments

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29
Q

Zone of Overlap

A

Dark region where thin and thick filaments overlap

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30
Q

Z lines

A

Bissect I bands. Mark boundaries between adjacent sarcomeres

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31
Q

Titin

A
  • Elastic protein
  • Extends from tips of thick filaments to Z line
  • keeps filaments in proper alignment
  • Aids in restoring sarcomere length
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32
Q

Thin Filaments

A

Contain F-actin, nebulin, tropomyosin, and troponin proteins

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33
Q

Filamentous actin (F-Actin)

A

Twisted strand composed of two rows of globular G-actin molecules. Active sites on G-band bind to myosin

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34
Q

Nebulin

A

holds F-actin strand together

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35
Q

Tropomyosin

A
  • Covers active sites on G-actin

- prevents actin-myosin interaction

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36
Q

Troponin

A
  • Globular protein.

- Binds tropomyosin, G-actin, and Ca

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37
Q

Ca + Troponin

A

Releases Tropomyosin

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38
Q

Thick Filaments

A
  • each contain about 300 myosin molecules

- core of titin recoils after stretching

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39
Q

Each myosin molecule consists of

A

Tail and head

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40
Q

Myosin tail

A

Binds to other myosin molecules

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41
Q

Myosin head

A
  • made of two globular protein subunits

- Projects toward nearest thin filament

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42
Q

Sliding-filament theory steps

A

1) H bands and I bands narrow
2) Zone of overlap widen
3) Z lines move closer together
4) Width of A bands remains constant
- Thus thin filaments must slide towards center of sarcomere

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43
Q

Excitable membranes

A
  • Found in skeletal muscle fibers and neurons

- Depolarization and repolarization events product action potentials

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44
Q

Action potentials

A

Electrical impulses

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45
Q

Skeletal muscle fibers contract due to

A

Stimulation by motor neurons

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46
Q

Neuromuscular junction (NMJ)

A
  • Synapse between a neuron and a skeletal muscle fiber
  • Axon terminal of motor neuron releases a neurotransmitter into synaptic cleft
  • ACh binds to and opens a chemically gated Na channel on muscle fiber
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47
Q

Neurotransmitter of neuromuscular junction

A

Acetylecholine (ACh)

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48
Q

Mechanism for action potential

A

ACh binds to and opens chemically gated Na channel on muscle fiber. Na enters cell and depolarizes motor end plate

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49
Q

Synaptic cleft

A

Narrow space that separates axon terminal of neuron from opposing motor end plate

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50
Q

Excitation-Contraction coupling

A
  • Action potential travels down T Tubules to triads
  • Ca binds to troponin and changes its shape
  • Troponin-tropomyosin complex changes position
  • Contraction cycle is initiated
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51
Q

roponin-tropomyosin complex changes position

A

It exposes active sites on thin filaments

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52
Q

Contraction Cycle

A

1) Contraction cycle begins
2) Active-site exposure
3) Cross-bridge formation (myosin binds to actin)
4) Myosin head pivoting (power stroke)
5) Cross-bridge detachment
6) Myosin reactivation

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53
Q

Generations of muscle tension

A
  • When muscle cells contract, they produce tension (pull)
  • To produce movement, tension must overcome load (resistance)
  • The entire muscle shortens at the same rate
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54
Q

Speed of shortening of muscles depends on

A

Cycling rate (number of power strokes per second)

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55
Q

Duration of a contraction depends on

A
  • Duration of neural stimulus
  • presence of free calcium ions in cytosol
  • Availability of ATP
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56
Q

As Ca is pumped back into SR and Ca conc in cytosol falls

A

1) Ca detaches from troponin
2) Troponin returns to original position
3) Active sites are re-covered by tropomyosin and the contraction ends

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57
Q

Rigor mortis

A

-Fixed muscular contraction after death

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58
Q

Rigor mortis results when

A
  • ATP runs out and ion pumps cease to function

- Calcium ions build up in cytosol

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59
Q

The amount of tension produced depends on the

A
  • Number of power strokes performed
  • Fiber’s resting length at time of stimulation
  • Frequency of stimulation
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60
Q

Length-tension relationship

A
  • Tension produced by a muscle fiber relates to the length of the sarcomeres
  • Max tension produced when maximum number of cross bridges formed
61
Q

Max tension occurs when

A

Zone of overlap is large

62
Q

Frequency of stimulation

A

Single neural stimulation produces a single contraction, or twitch

63
Q

Requirement of sustained muscular contraction

A

Requires many repeated stimuli

64
Q

Myogram

A

Graph showing tension development in muscle fibers

65
Q

Single twitch has three periods

A

Latent, contraction, relaxation

66
Q

Latent period

A

Action potential moves across sarcolemma. SR releases Ca

67
Q

Contraction phase

A
  • Calcium ions bind to troponin and cross-bridges form

- tension builds to a peak

68
Q

Relaxation phase

A
  • Ca levels in cytosol fall

- Cross-bridges detach and tension decreases

69
Q

Treppe

A

-Stair-step increase in tension

70
Q

Treppe caused by

A

Repeated stimulation immediately after relaxation phase. Produces a series of contractions with increasing tension

71
Q

Treppe typically seen in

A

Cardiac muscle and not skeletal muscle

72
Q

Wave summation

A

-Increasing tension due to summation of twitches

73
Q

Cause of wave summation

A

Repeated stiumulations before the end of relaxation period

74
Q

Tetanus

A

Maximum tension

75
Q

incomplete tetanus

A
  • Muscle produces near-max tension

- Caused by rapid cycles of contraction and relaxation

76
Q

Complete tetanus

A
  • higher stimulation frequency eliminates relaxation phase
  • Muscle is in continuous contraction
  • All potential cross-bridges form
77
Q

Tension produced by skeletal muscles

A

Depends on the number of stimulated muscle fibers

78
Q

Motor unit

A

Motor neuron and all of the muscle fibers it controls.

  • May contain few muscle fibers of thousands
  • All contract at the same time (fibers)
79
Q

Fasciculation

A
  • Involuntary “muscle twitch”

- Unlike a true twitch, it involves more than one muscle fiber

80
Q

Recruitment

A
  • Increase in the number of active motor units

- produces smooth, steady increase in tension

81
Q

Max tension in recruitment

A

achieved when all motor units reach complete tetanus

82
Q

Sustained contractions in recruitments

A
  • Produce less than max muscle tension

- motor units are allowed to rest in rotation

83
Q

Muscle tone

A
  • Normal tension and firmness of a muscle at rest

- Elevated muscle tone increases resting energy consumption

84
Q

Without causing movement, motor units actively

A
  • Stabilize positions of bones and joints

- Maintain balance and posture

85
Q

Types of muscle contraction

A

Isotonic and isometric. Based on pattern of tension production

86
Q

isotonic contraction

A

Skeletal muscle changes length

-resulting in motion

87
Q

Isotonic concentric contraction

A
  • muscle tension>load (resistance)

- Muscle shortens

88
Q

-Isotonic eccentric contraction

A

-Muscle tension

89
Q

Isometric contractions

A
  • skeletal muscle develops tension that never exceeds the load
  • Muscle does not change length
90
Q

Load and speed of contraction

A
  • are inversely related
  • the heavier the load, the longer it takes for movement to begin
  • Tension must exceed the load before shortening can occur
91
Q

Elastic forces during muscle relaxation and return to resting length

A
  • Tendons recoil after a contraction

- helps return muscle fibers to resting length

92
Q

Opposing muscle contractions during muscle relaxation and return to resting length

A

-Opposing muscles return a muscle to resting length quickly

93
Q

Gravity

A

Assists opposing muscles

94
Q

ATP is the only energy source used

A

directly for muscle contraction

95
Q

Contracting muscles use

A

alot of ATP

96
Q

Muscle store enough ATP to

A

start contraction

97
Q

More ATP must be generated to

A

sustain a contraction

98
Q

At rest, Skeletal muscle fibers produce

A

more ATP than needed

99
Q

ATP transfers energy to

A

Creatine

100
Q

Creatine phosphate (CP)

A

Used to store energy and convert ADP to ATP

101
Q

Creatine kinase

A

Catalyzes conversion of ADP to ATP using energy stored in CP

102
Q

ATP is generated by

A
  • Direct phosphorylation of ADP by CP
  • Anaerobic metabolism (glycolysis)
  • Aerobic metabolism (Citric acid cycle and electron transport chain)
103
Q

Glycolysis main points

A
  • Anaerobic process
  • important energy source for peak muscular activity
  • Breaks down glucose from glycogen stored in skeletal muscles
  • produces two ATP per molecule of glucose
104
Q

Aerobic metabolism

A
  • Primary energy source of resting muscles

- breaks down fatty acids

105
Q

Muscle metabolism

A

Skeletal muscle at rest metabolize fatty acids and store glycogen and CP

106
Q

During moderate activity (muscle metabolism)

A

muscles generate ATP through aerobic breakdown of glucose, primarily

107
Q

At peak activity, (muscle metabolism)

A

pyruvate produces via glycolysis is converted to lactate

108
Q

Recovery period

A

The time required after exertion for muscle to return to normal

109
Q

Lactate removal and recycling (Cori cycle)

A
  • Lactate is transferred from muscles to the liver
  • Liver converts lactate to pyruvate
  • Most pyruvate molecules are converted to glucose
  • Glucose is used to rebuilt glycogen reserves in muscle cells
110
Q

Oxygen debt

A

also called excess postexercise oxygen consumption (EPOC)

111
Q

After exercise or other exertion

A
  • Body needs more oxygen than usual to normalize metabolic activities
  • breathing rate and depth are increased
112
Q

Heat production and loss

A

Active skeletal muscle release up to 85 percent of heat needed to maintain normal body temp

113
Q

Several hormones increase metabolic activites in skeletal muscles

A
  • Growth hormone
  • testosterone
  • thyroid hormones
  • epinephrine
114
Q

Force

A

the maximum amount of tension produced

115
Q

Endurance

A

the amount of time an activity can be sustained

116
Q

Force and endurance depend on

A
  • types of muscle fibers

- Physical conditioning

117
Q

Three types of skeletal muscle fibers

A
  • Fast fibers
  • slow fibers
  • intermediate fibers
118
Q

Fast fibers

A
  • Majority of skeletal muscle fibers
  • Contract very quickly
  • large diameter
  • large glycogen reserves
  • few mitochondria
  • produce strong contractions, but fatigue quickly
119
Q

Slow fibers

A
  • slow to contract and slow to fatigue
  • small diameter
  • numerous mitochondria
  • High oxygen supply from extensive capillary network
  • contain myoglobin (red pigment that binds oxygen)
120
Q

Intermediate fibers

A
  • Mid-sized
  • little myoglobin
  • slower to fatigue than fast fibers
121
Q

White muscles

A
  • mostly fast fibers

- pale

122
Q

Red muscles

A
  • mostly slow fibers

- dark

123
Q

Most human muscles

A

contain a mixture of fiber types and are pink

124
Q

Muscle hypertrophy

A

Muscle growth from heavy training

125
Q

Hypertrophy causes increases in

A
  • diameter of muscle fibers
  • number of myofibrils
  • number of mitochondria
  • glycogen reserves
126
Q

Muscle atrophy

A

Reduction of muscle size, tone, and power due to lack of activity

127
Q

Changes in muscle tissue as we age

A
  • Skeletal muscle fibers become smaller in diameter
  • skeletal muscle fibers become less elastic
  • Tolerance for exercise decreases
  • Ability to recover from muscular injuries decreases
128
Q

Fibrosis

A

Increase in fibrous connective tissue

129
Q

Muscle fatigue

A

When muscle can no longer perform at a required level

130
Q

Muscle fatigue correlated with

A
  • Depletion of metabolic reserves
  • damage to sarcolemma and sarcoplasmic reticulum
  • decline in pH, which affects calcium ion binding and alters enzyme activities
  • weariness due to low blood pH and pain
131
Q

Anaerobic endurance

A
  • uses fast fibers and stimulates hypertrophy

- improved by frequent, brief, and intensive workouts

132
Q

Aerobic endurance

A
  • supported by mitochondria
  • does not stimulate muscle hypertrophy
  • training involves sustained, low levels of activity
133
Q

Improvements in aerobic endurance result from

A
  • alterations in the characteristics of muscle fibers

- improvements in cardiovascular performance

134
Q

Cardiac muscle cells

A
  • found only in the heart
  • have excitable membranes
  • striated like skeletal muscle cells
135
Q

Cardiac muscle cell characteristics

A
  • small
  • typically branched with single nucleus
  • Have short, wide T tubles (no triads)
  • have SR without terminal cisternae
  • almost totally dependent on aerobic metabolism
  • contact each other via interacalated discs
136
Q

Intercalated discs

A
  • Specialized connections

- Join sarcolemmas of adjacent cardiac muscle cells by gap junctions and desmosomes

137
Q

Intercalated disc function

A
  • Stabilizing positions of adjacent cells
  • maintaining three-dimensional structure of tissue
  • allowing ions to move from one cell to another
138
Q

Automaticity (cardiac muscle)

A

Contraction without neural stimulation

controlled by pacemaker cells

139
Q

Functional characteristics of cardiac muscle

A
  • nervous system can alter pace and tension of contractions
  • contractions last 10 times longer than those in skeletal muscle, and refractory periods are longer
  • wave summation and tetanic contractions are prevented due to special properties of sarcolemma
140
Q

Smooth muscle tissue exists in

A
  • Integumentary system
  • Cardiovascular and respiratory system
  • Digestive and urinary systems
  • reproductive system
141
Q

Structural characteristics of smooth muscle

A
  • long, slender, spindle-shaped cells
  • single, central nucleus
  • no T tubules, myofibrils, or sarcomeres
  • Scattered thich filaments with many myosin heads
  • thin filaments attached to dense bodies
  • no tendons or aponeuroses
142
Q

Smooth muscle functional characteristics

A
  • Excitation-contraction coupling
  • length-tension relationships
  • control of contractions
  • smooth muscle tone
143
Q

Excitation-contraction coupling

A
  • Free Ca in cytoplasms triggers contraction

- Ca binds calmodulin

144
Q

Calmodulin

A
  • Activated myosin light chain kinase

- allows myosin heads to attach to actin

145
Q

Length-tension relationship

A
  • Due to lack of sarcomeres, tension and resting length not directly related
  • even a stretched smooth muscle can contract
146
Q

Plasticity

A

the ability to function over a wide range of lengths

147
Q

Mutliunit smooth muscle cells

A
  • innervated in motor units

- each cell may be connected to more than one motor neuron

148
Q

Visceral smooth muscle cells

A
  • Not connected to motor neurons
  • arranged in sheets or layers
  • Rhythmic cycles of activity are controlled by pacesetter cells
149
Q

Smooth muscle tone

A
  • normal backgrond level of actvity

- can be decreased by neural, hormonal, or chemical factors

BIOL 242 Unit 2 Flashcards (1 decks)

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