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Unformatted text preview: Skeletal Muscle Attached to bones and responsible for their movement Skeletal muscle bundle of long fiber fiber is a single cell with multiple nuclei myofibrils Myofibrils= muscle + small fibers Myofibrils composed of 2 types of my filaments: Thick and Thin Thick: myosin molecules Thin: 2 strands of actin and 1 strand of regulatory protein Structure of a Sarcomere Sarcomere: 1 repeating unit Z line: attaches to thin filament I band: gap with only thin filament A band: length of thick filament H zone: only thick filament Sliding of filaments Sliding-filament model : As sarcomere shortens, the thick and thin filaments overlap one another Sliding due to actin and myosin interaction Myosin head and interaction with actin Myosin head powers muscle contractions and binds to ATP to hydrolyze it to ADP + P i that triggers steps for myosin to bind to actin forming cross bridges to pull thin filament toward the center of the sarcomere Creatine phosphate and glycogen allows for repetitive contractions Creatine: make ATP quickly by transferring P i to ADP Glycogen: breaks down glucose to generate ATP through glycolysis...
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- Spring '08