Muscle Contraction 2011 class notes

Muscle Contraction 2011 class notes - Muscle Muscle...

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Muscle Contraction and Motor Units BIO 335 2011 Craig Evinger
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Why Have A Nervous System? The Only Reason To Have A Nervous System Is So You Can Move Around To Get Food
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A Nervous System Is For Movement A Nervous System Is For Movement – Sea Squirts Sea Squirts Larval tunicates are free wimming animals with a swimming animals with a full nervous system and sensory systems. Larval tunicates attach to rocks and mature into adults. As sessile nimls they digest animls, they digest almost their entire nervous and sensory ystems and spend their systems and spend their time extracting organisms that they ump through their gut. pump through their gut. http://www.reefkeeping.com/issues/2005-03/rs/index.php
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Muscle Depolarization: Excitation Muscle Depolarization: Excitation - Contraction Coupling Contraction Coupling A Sarcomere Is The Fundamental Unit Of Muscle Fiber Contraction Actin Myosin Sliding-Filament Hypothesis Ca ++ entry into the myofibril enables the thin filaments ( actin ) to slide along the thick filaments ( myosin ). This action shortens the muscle to generate force.
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Muscle Depolarization: Excitation Muscle Depolarization: Excitation - Contraction Coupling Contraction Coupling How Ca++ Produces Movement Of Actin Along The Myosin 1. ACh release at the neuromuscular junction opens nicotinic-gated ion channels that depolarize the muscle. The action potential that sweeps own the sarcolemma depolarizes T bules that down the sarcolemma depolarizes T-tubules that releases Ca ++ . 2. Free Ca ++ binds to troponin, which undergoes conformational change that shifts tropomyosin a conformational change that shifts tropomyosin so that it no longer blocks myosin binding sites on the actin. 3. Myosin heads binds to the unblocked actin and the myosin head rotates. 4. Myosin heads disengage from actin by converting ATP to ADP 5. The actin-myosin binding and unbinding cycle continues as long as free Ca ++ and ATP are present. M scle rela ation occ rs beca se the 6. Muscle relaxation occurs because the sarcoplasmic reticulum actively sequesters Ca ++ using an ATP driven pump. T i th i bi di it 7. Troponin covers the myosin binding sites. From G. Matthews, Neurobiology http://www.blackwellpublishing.com/matthews/myosin.html
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Muscle Depolarization: Excitation Muscle Depolarization: Excitation - Contraction Coupling Contraction Coupling A Sarcomere Is The Fundamental Unit Of Muscle Fiber Contraction Binding of the actin to the myosin generates force and can shorten the muscle to move the body.
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This note was uploaded on 12/06/2011 for the course BIO 335 taught by Professor Cabot during the Fall '08 term at SUNY Stony Brook.

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Muscle Contraction 2011 class notes - Muscle Muscle...

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