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Muscle Contraction. Function. Movement L ocomotion ; blood pressure ; propulsion Support Soft Tissues S upport the weight of visceral organs; shield internal tissues Maintain Posture & Body Position Body Temperature Guard Entrances & Exits. Neural Impulse. Motor Neuron Fires
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Function • Movement • Locomotion; blood pressure; propulsion • Support Soft Tissues • Support the weight of visceral organs; shield internal tissues • Maintain Posture & Body Position • Body Temperature • Guard Entrances & Exits
Neural Impulse • Motor Neuron Fires • Acetylcholine is released from axon terminal and binds to the motor end plate on the other end of the synapse • http://www.youtube.com/watch?v=L2p73iuKJGY&feature=related
Muscular Impulse • Acetylcholine travels down transverse tubes • Initiates a muscular impulse
Sliding Filament Model • Ca2+ is released from the cisternae of the sarcoplasmic reticulum • Ca2+ binds to Troponin, which moves Tropomyosin, exposing myosin binding sites • Myosin cross-bridges (Myosin heads) bind to Actin
Sliding Filament Model • ADP is released, causing myosin to “flex” • ATP binds to cross-bridge, releasing myosin from actin • Repeat steps 4 -5 • http://www.youtube.com/watch?v=f0mDFP7qn1Y&feature=fvst(2:00 – 8:00) • http://www.youtube.com/watch?v=gJ309LfHQ3M
Ending Contraction • Nerve impulse stops – ending release of acetylcholine • Acetylcholinesterasedecompses leftover acetylcholine • Ca2+ are pumped back in to cisternae • Making binding sites on actin filament unavailable
Types of Muscle Fibers Fast Fibers Slow Fibers Smaller than fast Take 3 times as long to contract Continue contracting after fast muscles are fatigued Dark meat • Most muscle fibers in the body • Contract in 0.01 second or less • Powerful contractions • White meat