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Movement using ATP

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This is the video on muscle contraction to be watched as part of the webquest on photosynthesis and cellular respiration.

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we move our bodies by shortening or Contracting are muscles take a closer look a muscle consists of parallel muscle fibers each fiber is a single cell in close contact with a motor neuron each muscle cell contains bundles of parallel myofibrils shown in red surrounded by endoplasmic reticulum or ER an action potential rolling down a motor neuron initiates an action potential in the muscle cell the action potential spreads along the membrane and down to bills that extend the cytoplasm causing the myofibrils to contract  each myofibril consists of a series of sarcomeres arranged end-to-end play soccer is the contractile unit of muscle which sarcomere consists of thick filaments of myosin shown in purple and thin filaments of actin shown in Orange a sarcomere contracts when actin filaments slide past its myosin filaments contraction shortens the sarcomere but does not change the length of the actin or myosin filaments the myosin filaments have heads that bind and pull actin repeatedly shortening the sarcomere how do the myosin heads pull actin in a relaxed muscle the myosin binding sites on actin are blocked by a protein blacks and ADP and phosphate are bound to each myosin head an action potential causes the ER to release calcium ions which bind to the protein complex causing it to shift and expose the myosin binding sites the myosin head binds to actin when ADP and phosphate are the myosin head bands pulling the actin this is called the Powerstroke next ATP binds to the myosin head causing it to from Acton when the ATP is broken down to ADP and phosphate the myosin head extends  the sequence repeats as long as Kelsey ions are present Vine Powerstroke detach x 10 the combined work of many myosin heads what is the actin filaments to slide past the myosin filaments when the action potentials stopped calcium ions are pumped back into the ER the binding sites on actin are again blocked and the muscle relaxants during muscle contraction actin filaments are pulled toward the center of the sarcomere the simultaneous contraction of the sarcomere what's the myofibrils and the entire muscle cell contract this is how a muscle cell responds to action potentials in the motor neuron when many muscle cells contract together the result is movement

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Movement using ATP

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