Muscle Physiology 1

Role of ca2 if none troponin holds tropomyosin over

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Unformatted text preview: Cyclical formation of links between actin and myosin Result in sliding filaments towards the M line of sarcomere Myosin head undergoes conformation changes back and forth High energy form: ADP/Pi- myosin, high affinity for actin Low energy form: ATP- myosin, lowaffinity for actin Conformational changes rely on ATP hydrolysis via myosin ATPase Power stroke: myosin head propels thin filament toward center Movement of oar propelling boat Thick and thin filaments detach Oar breaks contact with the water Myosin head returns to initial position Oar moved to new position, cycle starts again Muscle cell continuously generates force during contraction Crossbridge cycles of different myosin molecules are out of phase Never break complete contact between thick and thin filaments during contraction. Necessary events: action potential in the sarcolemma causes contraction Dependent on neural input from motor neuron Requires calcium release from the sarcoplasmic reticulum. Role of Ca2+: If none: troponin holds tropomyosin over myosin binding sites on actin, reduces the crossbridges between actin and myosin, muscle relaxed If present: binds to...
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