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17 Cards in this Set
- Front
- Back
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Thick myofilament |
made of Myosin protein |
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Thin myofilament |
made of Actin protein |
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H zone |
Bit in middle w/ only myosin Shorter during contraction, bc actin filaments slide over it, covering it |
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A band |
Length of a myosin filament, including the H zone and the area of overlap of myosin and actin Same length during contraction (These are Dark hence A band) |
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I Band |
Space between 2 myosins containing only actin Gets shorter in contraction (These are light hence I band) |
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Z line |
Ends of each sarcomere |
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M line |
Middle of myosin filaments |
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Physical differences between fast twitch and slow twitch |
Fast twitch Whitish in colour; little myoglobin therefore can't store much O2
Few mitochondria or blood vessels, b/c E released quickly through anaerobic resp.
Slow twitch Reddish in colour; lots of myoglobin Lots of mitochondria and blood supply |
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Role of Ca2+ ions |
Change shape of tropomyosin, so it moves out of actin-myosin binding site
Activate ATP hydrolase (As well as role in cholinergic synapses, where they trigger synaptic vesicles to move towards presynaptic membrane etc.) |
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Role of ATP |
E for myosin head to bend E to break actin-myosin cross bridge Actively transport Ca2+ back to the sarcoplasmic reticulum |
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Binding sites on myosin head |
Each head has a binding site for: actin ATP |
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Sarcomere |
Cell membrane of muscle fibre cells |
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Transverse (T) tubules |
Inward folds of the sarcolemma; help to spread electrical impulses throughout sarcoplasm so they reach all parts of the muscle fibre |
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Sarcoplasmic reticulum |
Network of internal membranes, which runs through sarcoplasm. Stores and releases Ca2+ ions |
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Myofibrils |
Long, cylindrical organelles which make up muscle fibres. Made up of myosin and actin proteins |
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Where is ATP obtained from? |
Aerobic respiration; mostly from ox. phosph. Anaerobic resp; glycolysis, but pyruvate produces lactate, which builds up and fatigues muscles ATP-Phosphocreatine (PCr) System; anaerobic and alactic. PCr runs out after few seconds, therefore v.short burst of vigorous exercise e.g. tennis serve. |
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ATP-PCr System |
Phosphate taken from Phosphocreatine (PCr) to phosphorylate ADP PCr stored inside cells, and runs out after few seconds Some of creatine broken down into creatinine; removed via kidneys. Creatinine levels higher in people w/ kidney damage, and people who exercise reg. and have high muscle mass. |
