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Published byWarren Johnson Modified over 9 years ago
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Name the following movements: ◦ Increasing angle of joint (ex. Straightening arm) ◦ Moving around longitudinal axis: ◦ Moving a limb away from midline of body:
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Muscle Fascicle (Muscle bundles) Muscle fibers (muscle cells) Myofibrils Myofilaments (thick and thin)
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Cell membrane of skeletal muscle cells
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1 muscle fiber = many myofibrils 1 myofibril = many thick and thin filaments The thick and thin filaments form the smallest functional unit of muscle the sarcomere
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Made of proteins ◦ Structural: make up the structural framework of muscles ◦ Contractile: involved in the process of contraction ◦ Regulatory: not part of contraction, but they regulate it
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Actin (thin filament) has binding sites for myosin
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1950s – scientists observed that the length of thick and thin filaments stayed the same during muscle contraction This led to the Sliding Filament Theory: ◦ During muscle contraction, the thick and thin filaments do not shorten, but slide on one another which results in the shortening of the sarcomere and the entire muscle
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1. Myosin head binds to ATP 2. Myosin head gets energized
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3. Crossbridge forms between myosin head and actin
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4. Power stroke causes filaments to slide
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5. Another ATP molecule binds to myosin head causing it to release from actin and return to original position
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http://www.youtube.com/watch?v=Ct8AbZn_ A8A http://www.youtube.com/watch?v=Ct8AbZn_ A8A
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How is the sliding filament theory similar to these doors?
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Troponin and Tropomyosin (regulatory proteins) depend on Calcium ions Troponin: has binding site for calcium ions Tropomyosin: covers binding site on actin
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What would happen if there are no Calcium ions present?
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6 most important chemicals (molecules): ◦ Myosin, actin, tropomyosin, troponin, ATP, Calcium
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Kahoot.it
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