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Download 7Movement - Mission Hills High School
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Chapter 30 • How skeletal muscle contracts. • Cellular events that lead to muscle contraction. • Attached to bones by tendons and responsible for the movement of bones • Each long fiber is a single muscle cell • Each muscle fiber is a bundle of myofibrils which are made of thin filaments (actin) and thick filaments (myosin) • • • • • Smallest unit of contraction Z lines mark the borders of sarcomeres M line is the center of the sarcomere Sarcomeres contract when stimulated The sliding-filament model states that the actin (thin filaments) slide toward the M line so that they overlap the myosin (thick filaments) more during a contraction • Motor units are made of neurons and the muscle fibers they control • The area where the axon of the neuron contacts the muscle fibers is the neuromuscular junction • Action potentials release acetylcholine which stimulate the muscle fibers to contract https://www.youtube.com/watc h?v=BMT4PtXRCVA
