Lecture 21, Ch. 49

Lecture 21, Ch. 49 - 3- Releasing ADP and (Pi), myosin...

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Lecture #21      Date ____ Chapter 49 ~ Sensory and Motor Mechanisms
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Vertebrate Skeletal Muscle Contract/relax: antagonistic pairs w/skeleton Muscles: bundle of…. Muscle fibers: single cell w/ many nuclei consisting of…. Myofibrils: longitudinal bundles composed of…. Myofilaments: •Thin~ 2 strands of actin protein and a regulatory protein •Thick~ myosin protein Sarcomere: repeating unit of muscle tissue, composed of…. Z lines~ sarcomere border I band~ only actin protein A band~ H zone~ central sarcomere; only myosin
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Sliding-filament model Theory of muscle contraction Sarcomere length reduced Z line length becomes shorter Actin and myosin slide past each other (overlap increases)
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Actin-myosin interaction 1- Myosin head hydrolyzes ATP to ADP and inorganic phosphate (Pi); termed the “high energy configuration” 2- Myosin head binds to actin; termed a “cross bridge”
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Unformatted text preview: 3- Releasing ADP and (Pi), myosin relaxes sliding actin; low energy configuration 4- Binding of new ATP releases myosin head Creatine phosphate~ supplier of phosphate to ADP Muscle contraction regulation, I Relaxation : tropomyosin blocks myosin binding sites on actin Contraction : calcium binds to toponin complex; tropomyosin changes shape, exposing myosin binding sites Muscle contraction regulation, II Calcium (Ca+)~ concentration regulated by the. Sarcoplasmic reticulum~ a specialized endoplasmic reticulum Stimulated by action potential in a motor neuron T (transverse) tubules~ travel channels in plasma membrane for action potential Ca+ then binds to troponin Muscle contraction QuickTime and a Cinepak decompressor are needed to see this picture....
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Lecture 21, Ch. 49 - 3- Releasing ADP and (Pi), myosin...

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