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51 Cards in this Set
- Front
- Back
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endomysium |
separates individual muscle fibers from one another |
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perimysium |
separates 10-100 muscles fibers into fascicles |
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fascicles |
bundles of 10-100 muscle fibers |
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epimysium |
outermost layer surrounds numerous bundles of fascicles |
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skeletal muscle cells arise from _________ as _________ |
mesenchyme, myoblasts |
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do mature muscle cells divide? |
no |
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how are muscles cells grown? |
hypertrophy |
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can you repair heavily damaged muscle cells? |
no |
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sacromere |
fundamental functional unit of the myofibril |
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proteins that make up myofibril |
contractile proteins, regulatory proteins, structural proteins |
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contractile proteins |
generate force during contraction |
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regulatory proteins |
switch the contraction process on and off |
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structural proteins |
align the thick and thin filaments provide elasticity and extensibility link myofibrils to the sarcolemma |
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myosin |
contractile protein thick filament motor protein converts atp to motion hexagonal symmetry of heads |
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actin |
contractile protein thin filament linear arrays of actin provide the track that myosin moves on |
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tropomyocin |
regulatory protein covers myosin-binding sites, blocks myosin binding to actin |
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troponin |
regulatory protein with ca++, causes tropomyocin to uncover myosin binding sites so contraction can occur |
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titin |
structural protein stabilizes myosin provides elasticity and extensibility of myofibrils extends from z disc to m line |
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myomesin |
structural protein binds think filaments together, anchors titin at M line |
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alpha-actin |
structural protein binds thin filaments together, anchors titin at z disc |
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dystrophin |
structural protein links thin protein to the sarcolemma |
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contraction |
with ca++: -myosin heads attach to thin filament and walk at both ends of the sacromere, pulling the thin filaments toward the center and shortening the muscle |
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atp energy |
pumps ca2+ back into sarcoplasmic reticulum |
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cellular atp reserve has enough energy for |
1-2 seconds of contraction (has to be regenerated) |
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excess atp is used to synthesize |
creatine phosphate, a more stable energy source -- Provides ~15 seconds of contraction |
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when creatine is exhausted |
switch to anaerobic fermentation |
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anaerobic fermentation |
muscles obtain glucose from blood, stored glycogen -without oxygen, glycolysis can generate a net gain of 2 atp from every glucose molecule, converting glucose to lactic acid -provides enough atp for about 30-40 seconds maximum activity |
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aerobic metabolism |
after 40 s of anaerobic, respiratory and cardiovascular systems can deliver oxygen fast enough to meet demands -pyruvate converted to acetyl-CoA, enters citric acid cycle in mitochondria -gives 38 molecules of atp/glucose molecule, wasting CO2 and water -30 mins, energy equally from sugar and fatty acid >30 mins, just fatty acid |
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E(xcess)P(ost-exercise)O(xygen)C(onsumption) |
replenishes atp and creatine phosphate stores replaces oxygen reserves on myoglobin oxygen to liver oxygen to other cells |
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red muscle fibers |
high myoglobin content dark meat more mitochondria more blood capillaries |
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white muscle fibers |
low myoglobin count white meat |
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types of muscle fiber |
slow oxidative fast oxilative-glycolitic fast glycolytic |
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slow oxidative fibers |
smallest least powerful dark red mostly aerobic metabolism slow contractions 100-200 ms twitch resistant to fatigue sustained contractions for hours posture (neck, back, legs) |
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fast oxidative-glycolitic fibers |
intermediate size lots of myoglobin and capillaries dark red mostly aerobic, some anaerobic moderate resistance to fatigue faster contraction <100 ms twitch walking and sprinting (legs) |
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fast glycolitic fibers |
largest powerful contractions low myoglobin few blood capillaries few mitochondria mostly glycolysis (anaerobic) fast contractions fatigue quickly intense anaerobic movement for short duration (shoulders, arms) |
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fiber distribution |
most muscles are mixtures of all in varying proportions depending on action, training, and genetics |
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force of contraction |
single fiber: controlled by impulse rate entire muscle: controlled by impulse rate and number of triggered fibers |
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maximum tension is dependent on: |
size of motor unit rate of impulse arrival amount of stretch before contraction nutrient availability |
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twitch contraction |
response to a single action potential 20-200 ms |
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latent period |
delay between stimulus and contraction (2 ms) |
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contraction period |
10-100 ms ca++ binds to troponin myosin binding sites are exposed on actin crossbridges form |
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relaxation period |
ca++ transported to sr myosin binding sites covered by tropomyosin myosin heads detach from actin |
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muscle tone |
small amount of tension due to weak contractions of motor units small groups of motor units are alternatively active and inactive to sustain muscle tone keeps skeletal muscles firm maintains posture flaccid with loss of nerve input |
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isotonic contraction |
constant tension while muscle changes length for moving objects |
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concentric contraction |
muscle shortens |
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eccentric contraction |
muscle lengthens |
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isometric contraction |
tension is not great enough to cause muscle to change its length i.e. holding a book steady in outstretched arms |
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cramps are caused by |
inadequate blood flow, low electrolytes, overuse, and dehydration |
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tics |
involuntary spasmodic contractions of normally voluntary muscles |
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fasciculation |
brief twitch of an entire motor unit |
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fibrillation |
spontaneous contraction of a single muscle fiber |
