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Anatomy and Physiology > Muscular System > Flashcards

Muscular System Flashcards

1
Q

muscles

A

convert chemical energy into mechanical energy

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2
Q

muscle functions

A
  1. motility
  2. maintain posture
  3. stabilize joints
  4. generate heat
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3
Q

characteristics of muscle tissue

A

excitability
contractility
extensibility
elasticity

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4
Q

excitability

A

receives and responds to stimuli

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5
Q

contractility

A

forcibly shortens in length

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6
Q

extensibility

A

stretched or extended

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7
Q

elasticity

A

recoil to original resting length

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8
Q

three types of muscle tissue

A

skeletal
cardiac
smooth

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9
Q

skeletal muscle tissue

A

attaches to and covers bony skeleton
responsible for body motility
contracts rapidly but fatigues easily
controlled at neuromuscular junctions

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10
Q

parts of muscle organ

A

muscle fibers
blood vessels (O2, nutrients, wastes)
nerves (control)
connective tissues (support and reinforce)

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11
Q

types of connective tissue sheaths

A

epimysium
perimysium
endomysium

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12
Q

epimysium

A

dense irregular tissue surrounding muscle
keeps fascicles together

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13
Q

perimysium

A

dense irregular tissue surrounding fascicle
keeps muscle fibers together

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14
Q

endomysium

A

areolar tissue surrounding fiber

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15
Q

direct muscle attachment

A

epimysium fuses to periosteum of bone
muscle to bone

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16
Q

indirect muscle attachment

A

connective tissue extends beyond muscle as tendon or aponeurosis to connect to bone, cartilage, or other muscle

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17
Q

sarcolemma

A

muscle plasma membrane
glycosomes- glycogen storage
myoglobin
mitochondria

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18
Q

T-tubules

A

invaginations of membrane
conduct electrical impulses to deepest region of muscle
stimulated by nervous system
cause release of calcium from SR

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19
Q

sarcoplasm

A

cytoplasm of muscle cell

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20
Q

sarcoplasmic reticulum SR

A

smooth ER that stores calcium and surrounds myofibrils
lies next to T-tubules

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21
Q

muscle fiber cells

A

each fiber is one long, multinucleated cell
10-100 micrometers diameter, 30cm long
made up of 80% myofibrils

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22
Q

myofibril

A

contractile organelle
made up of myofilaments and sarcomeres

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23
Q

myofilaments

A

actin (thin) and myosin (thick) motor proteins

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24
Q

sarcomere

A

smallest functional unit for contractions
region between two Z discs - stacked end to end within myofibrils
made up of myofilaments

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25
Q

striations

A

dark A bands- overlap of myosin and actin
light I bands- ends of sarcomere, not much overlap

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26
Q

elastic filaments

A

align myosin and actin
help with recoil after stretching

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27
Q

dystrophin

A

anchors actin filaments to sarcolemma and extracellular matrix

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28
Q

thick myosin filaments

A

compose central A band
rod-like tail with globular heads
head forms cross bridges
ATPase

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29
Q

thin actin filaments

A

globular proteins joined together to form filament
compose I band and partially overlapping A band
active sites for myosin binding

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30
Q

tropomyosin

A

regulates contractions
covers active sites on actin - prevents grabbing from myosin heads

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31
Q

troponin

A

regulates contractions
moves tropomyosin off active site
binds calcium

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32
Q

sliding model of contraction

A

myosin moves thin actin filaments toward center of sarcomere
entire muscle shortens as multiple sarcomeres contract in unison

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33
Q

cross bridge cycling steps

A
  1. myosin head attaches to actin forming cross bridge- attached ADP and Pi
  2. Pi released, initiating power stroke- myosin head pivots and bends as it pulls on actin sliding it toward M line, then ADP releases
  3. new ATP attaches to myosin head, releases link between myosin and actin
  4. ATP split into ADP and Pi, myosin head energized and cocked into high energy conformation
  5. repeat step 1
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34
Q

muscle needs to contract

A

ATP
calcium
signal from nervous system

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35
Q

rigor mortis

A

muscles stiffen 3-4 hours after death
dying cells cannot exclude calcium, still flows and stimulates muscle contraction
ATP no longer produced
cannot release actin and myosin filaments
muscle proteins eventually breakdown

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36
Q

nerve impulse

A

stimulates skeletal muscle contraction
creates action potential across sarcolemma and down T-tubules
stimulates release of calcium from SR

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37
Q

neuromusclar junction

A

motor neuron connects with muscle cell

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38
Q

3 components of neuromuscular junction

A

axon terminal
motor end plate
synaptic cleft

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39
Q

axon terminal

A

contains vesicles with neurotransmitter acetylcholine

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40
Q

motor end plate

A

contains acetylcholine receptors

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41
Q

synaptic cleft

A

space separating axon end from muscle fiber

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42
Q

excitation-contraction coupling

A

action potential reaches end of axons
Ach released to cleft
Ach binds to receptors on motor plate
depolarization
action potential propagates along T-tubules
calcium released from SR
calcium binds to troponin, troponin moves tropomyosin off actin binding site

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43
Q

depolarization

A

positive Na+ ions flood cell
creates action potential across membrane

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44
Q

when can cell be stimulated again?

A

after repolarization is complete
refractory period- cant restimulate muscle cell after first stimulation

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45
Q

3 mechanisms to remove signal to repolarize

A
  1. acetylcholine destruction by acetylcholinesterase
  2. repolarization of membrane- back to resting potential
  3. resting intracellular calcium levels restored
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46
Q

mesodermal myoblasts

A

fuse together and develop sarcomeres for skeletal muscles
cannot divide again or repair itself

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47
Q

satellite cells

A

muscle stem cells, can give rise to new myoblasts and satellite cells
amount declines with age
muscle fibers can lengthen or thicken

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48
Q

motor unit

A

one motor neuron and all the muscle fibers it signals
number of fibers varies from 4 to hundreds
one nerve axon branches and forms many junctions

49
Q

muscle twitch

A

response to single stimulation

50
Q

latent period

A

action potential is spreading across sarcolemma

51
Q

period of contraction

A

myosin fibers pull actin fibers
cross bridge cycling

52
Q

period of relaxation

A

calcium pumped back into smooth ER
finished muscle contraction and cell resets

53
Q

temporal/wave summation

A

frequent stimuli increase contractile force
produces smooth continual muscle contractions by rapidly stimulating specific fibers
relaxation time between twitches decreases, calcium gets higher

54
Q

unfused tetanus

A

rapid stimuli
sustained muscle contraction

55
Q

fused tetanus

A

higher stimulus frequency
no relaxation between stimuli

56
Q

recruitment

A

overtime, stimulus recruits more and more muscle fibers to do work
multiple bigger motor units control strength of contraction

57
Q

threshold stimulus

A

stimulus which first observable contraction occurs

58
Q

maximum stimulus

A

all motor units recruited
strongest stimulus that causes contractile force
most contraction muscle can do

59
Q

size principle

A

smallest/most excitable motor units activated first
largest/slowest motor units activated last

60
Q

motor units stimulated asynchronously

A

some units in unfused tetanus, some resting
prolonged contractions by delaying fatigue

61
Q

types of muscle contractions

A

muscle tone
isotonic
isometric

62
Q

muscle tone

A

stretch receptors stimulate low level of contraction
maintains posture and joints
no net movement
keeps muscles healthy and ready

63
Q

isotonic

A

muscle shortens
muscle develops enough tension to lift weight

64
Q

isometric

A

no length change
load is greater than force possible to lift
reaches peak tension developing capability

65
Q

the greater the load…

A

the briefer the duration of muscle shortening
the slower the muscle shortening

66
Q

overload principle

A

forcing muscle to work promotes increased muscular strength
adapt to increasing demands- accumulate more organelles- gets larger
muscles must be overloaded to produce further gains

67
Q

4 components that determine strength of muscle contraction

A

frequency of stimulation
number of muscle fibers recruited
size of muscle fibers
degree of muscle stretch (filament overlap)

68
Q

3 sources of ATP generation

A
  1. creatine phosphate
  2. anaerobic glycolysis
  3. aerobic respiration
69
Q

creatine phosphate

A

stored in muscle cells
maximum power for 15 seconds
CP + ADP –> ATP + creatine

70
Q

anaerobic glycolysis

A

no oxygen required
one glucose = 2 ATP
energy for 30-40 seconds

71
Q

aerobic respiration

A

requires oxygen and glycogen
glucose produces 32 ATP
slower- more energy for longer time periods

72
Q

aerobic endurance

A

amount of time muscle can use aerobic respiration

73
Q

anaerobic threshold

A

point at which muscle must convert to anaerobic glycolysis

74
Q

what is used for short surges of power?

A

ATP stores in muscle
creatine phosphate
anaerobic glycolysis

75
Q

what is used for long exercise?

A

aerobic respiration

76
Q

what is used for prolonged/lack of oxygen exercise?

A

anaerobic glycolysis

77
Q

muscle fatigue

A

inability to contraction despite stimulus
due to ionic imbalances or decreased glycogen

78
Q

ionic imbalances in muscle fatigue

A

K ions accumulating in T tubules interferes with SR calcium release
inorganic phosphate released from creatine interfere with SR calcium or myosin release

79
Q

recovery

A

oxygen reserves in myoglobin replenished
lactic acid converted to pyruvic acid/glucose
glycogen, ATP, and CP stores replenished

80
Q

excess postexercise oxygen consumption

A

extra amount of O2 needed to restore balance

81
Q

fast vs slow muscle fiber types

A

different speeds of contraction based on:
myosin ATPase rate
activity of motor neuron
release of calcium

82
Q

oxidative vs glycolytic muscle fiber types

A

rely on different ATP production rates

83
Q

fast glycolytic fibers

A

anaerobic respiration
fatigue easily
thick, rapid power
hitting baseball

84
Q

slow oxidative fibers

A

aerobic respiration
fatigue resistance, endurance
thin, little power
marathoners

85
Q

fast oxidative fibers

A

in between
contract quickly
oxygen dependent
sprinting, walking

86
Q

aerobic exercise increases:

A

muscle capillaries
number of mitochondria
myoglobin synthesis

87
Q

resistance exercise increases:

A

muscle fiber hypertrophy
number of mitochondria
myofibrils
glycogen stores
connective tissue sheaths

88
Q

powerful levers

A

effort further away from fulcrum than the load
mechanical advantage

89
Q

speech levers

A

effort is closer to fulcrum than load
mechanical disadvantage

90
Q

first class levers

A

fulcrum between effort and load
strength or speed

91
Q

second class levers

A

load between fulcrum and effort
wheelbarrow
strength
least common

92
Q

third class levers

A

effort between fulcrum and load
tweezers
speed/range of motion
most common

93
Q

cardiac muscle tissue

A

only found in heart
pacemaker sets contraction rate - gap junctions
intercalated discs connect cells
doesn’t fatigue
lots of mitochondria

94
Q

characteristics of smooth muscle

A

sheets of spindle shaped cells
connected by gap junctions
endomysium surrounds them

95
Q

location of smooth muscle

A

hollow visceral organs
respiratory, digestive, urinary, reproductive tracts

96
Q

peristalsis

A

alternating contraction of longitudinal and circular layers of smooth muscle
2 layers are running perpendicular to each other

97
Q

longitudinal layer contraction

A

organ shortens, circumference increases

98
Q

circular layer contraction

A

organ elongates, circumference decreases

99
Q

varicosities

A

swollen regions of autonomic nerve fibers on smooth muscle fibers

100
Q

diffuse junctions

A

wide synaptic cleft where varicosities release neurotransmitters

101
Q

regulation of smooth muscle contraction

A

neural
hormonal
chemical

102
Q

neural regulation of smooth muscle

A

autonomic nervous system uses variety of different neurotransmitters to determine contraction or relaxation

103
Q

hormonal/chemical regulation of smooth muscle

A

neuronal signal not always needed
spontaneous contractions
hormones or chemicals can alter calcium

104
Q

differences between smooth and skeletal

A

smooth :
greater stretch and tension
slow, prolonged contractile activity
calcium from extracellular space
calmodulin regulation (no troponin)
actin and myosin arranged diagonally with intermediate filament bundles
regenerate throughout adulthood

105
Q

stress relaxation response

A

adaption to stretch/larger volume
allow time before contracting

106
Q

smooth muscle contraction

A

spontaneous general depolarization
cells connected by gap junctions
calcium floods from extracellular space and SR
calcium binds to calmodulin to activate myosin light chain kinase
actin and activated myosin create sliding filaments with ATP
calcium released back to extracellular space after

107
Q

prolonged contraction in smooth muscle

A

myosin takes longer to release from actin
slow ATPase activity

108
Q

multiunit smooth muscle

A

innervated independent fibers activated by hormones or neurotransmitters from autonomic system
lungs airways, large arteries, pupils, arrector pili

109
Q

unitary smooth muscle

A

innervated by varicosities activated spontaneously or by hormones/neurotransmitters, signal transduced through gap junctions
lining of all hollow organs except heart

110
Q

muscle cramps

A

sudden involuntary contractions of skeletal muscle
overexertion, dehydration, poor blood flow, ionic imbalance
stretching

111
Q

twitching eyelids

A

involuntary spasm of eyelid muscle
fatigue, stress, caffeine
repeated twitching, light sensitivity, blurry vision
more sleep, less caffeine, eye drops

112
Q

muscular dystrophy

A

muscle destroy disease
fibers atrophy and replaced by fat and connective tissue deposits

113
Q

Duchenne’s muscular dystrophy

A

x-linked recessive disease (mother to son)
progresses upward from extremities
die of respiratory failure in 20-30s
lack of dystrophin protein that connects actin to ECM
steroids, PT, drugs, ventilation, experimental

114
Q

Becker’s muscular dystrophy

A

dystrophin is partially functional
slower and less predictable
survive to mid to late adulthood

115
Q

myasthenia gravis

A

autoimmune disorder with unknown cause
loss of acetylcholine receptors on motor end plate
muscle weakness
drugs

116
Q

dystonia

A

involuntary sustained contractions
miscommunication between brain and muscle
tremor and twitching
drugs, therapy, surgery, brain stimulation

117
Q

ptosis

A

drooping eyelid
weakness of muscle that raises eyelid, damage to nerves that control that muscle
caused by aging, injury, disease
surgery

118
Q

osgood-schlatter disease

A

painful swelling of bump on anterior tibial tubercle
overuse and repetitive injuries during growth
seen in youth sports
rest and reduce stress

119
Q

strabismus

A

eye muscles are not properly coordinated

Anatomy and Physiology (12 decks)

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