human phys lec 11 - Cell...

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ell and molecular physiology of muscle contraction Cell and molecular physiology of muscle contraction
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pes of muscle Types of muscle Striated muscles Smooth muscles 1. Skeletal muscle Fast twitch Many types Includes any muscle that not obviously striated Slow twitch 2. Cardiac muscle entricular muscle is not obviously striated Blood vessels, intestine, stomach, urinary Ventricular muscle Atrial muscle Nodes and bladder, many others. conducting fibers From Latin striatus meaning ‘striped’
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Transmission EM image of skeletal muscle Light microscopy of skeletal muscle fibers
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ction potentials in skeletal muscle and cardiac muscle Action potentials in skeletal muscle and cardiac muscle Action potential in frog sartorius muscle fiber Action potential in frog heart muscle (ventricle) 0 mV 0 mV Time (ms) Adrian RH, Peachey LD (1973) urnal of Physiology 35: 103 31 1 second Macfarlane WV (1960) irculation Research : 47 6 80 mV Journal of Physiology 235: 103 131 Circulation Research 8: 47 56 These action potentials trigger contractions, but note the difference in the me urse of the spikes Much faster in skeletal muscle time course of the spikes. Much faster in skeletal muscle.
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Functional components of a striated muscle cell T tubule Sarcolemma Sarcoplasmic reticulum Mitochondrion Thin filament (actin) Thick filament (myosin) Sarcomere Myofibril The sarcomere is the basic contractile element of the muscle reek rco eaning Greek sarco meaning ‘meat’ or ‘flesh’ Greek meros meaning ‘part’
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T tubules are invaginations of the plasma membrane Sarcolemma (plasma membrane) Transverse tubule (T tubule) Sarcoplasmic reticulum (SR), ores Ca 2+ Sarcomere stores Ca
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ctin thin ne Structure of a single myofibril Z disk Z disk Actin thin filament M line I Band M line A Band Myosin thick filament I Band Sarcomere
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portant proteins of the rcomere M line Important proteins of the sarcomere Z disk (many proteins) Z disk Titin Myosin Actin Actin Troponin Tropomyosin Myosin
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Proteins of the Z line (as of 2009) Z line
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Myosin and actin change their alignment hen muscles generate force when muscles generate force Z line Z line Contraction Relaxation e e Z line Z line This is called the ‘sliding filament mechanism’ of muscle contraction It is the actin filaments that slide as a result of myosin function
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A myosin thick filament (made of several myosin molecules) Head groups oriented in opposite directions on the two ends of the thick filament Globular head region Binds to actin, hydrolyzes ATP
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This note was uploaded on 01/26/2012 for the course BIOL 3324 taught by Professor Ziburkus during the Spring '07 term at University of Houston.

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human phys lec 11 - Cell...

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