SC BIOL 460 - Smooth Muscle and the Heart (3 pages)

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Smooth Muscle and the Heart

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Smooth Muscle and the Heart


single and multiunit of smooth muscle and the heart/circulatory system

Lecture number:
Lecture Note
University Of South Carolina-Columbia
Biol 460 - General Physiology
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BIOL 460 1st Edition Lecture 18 Outline of Last Lecture I Muscle Twitch II Skeletal Muscle Fiber Types III Cardiac Muscle IV Smooth Muscle Outline of Current Lecture I Smooth Muscle a Multiunit b Single unit c Excitation contraction coupling II The Heart Circulatory System Chapter 9 Current Lecture Smooth Muscle Review 1 Innervated by autonomic neurons 2 Two types a Multiunit iris of eye individual smooth muscle cells all receiving innervation by one axon b Single Unit i Much more common ii Walls of hollow organs iii Innervation by synapses en passant iv Cells are connected together with gap junctions v All contract together vi Generate peristaltic waves 3 Non striated no A and I bands no sarcomeres 4 Cells are spindle shaped uninucleate 5 No z discs thin filaments attach to sarcolemma or masses of protein called dense bodies 6 Thick myofilaments are less common much more actin than myosin 16 1 ratio These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute 7 Thick myofilaments are composed of myosin organized with cross bridges parallel to shaft unlike skeletal muscle 8 No bare zone without cross bridges 9 LOOK AT FIGURE 12 37 10 Single unit SM innervation occurs via gap junctions 11 Smooth muscle a More thin thick ratio 16 1 than skeletal muscle 2 1 b No bare zone on thick myofilament c Cross bridges parallel to myosin band d Makes smooth muscle better able to stretch e Slow sustained contractions slow myosin ATPase s 12 Excitation Contraction coupling in Smooth muscle a Trigger is Ca2 from extracellular environment NOT FROM SR b Sarcolemma contains Ca2 VGC c EPSPs Graded contractions result of amount of Ca2 going in cell d Low Ca2 weak contraction e High Ca2 strong contraction f No troponin or tropomyosin g Ca2 in cell bonds to calmodulin making Ca2 calmodulin complex h Activates myosin light chain kinase i Phosphorylates myosin light chains j Cross bridges attach to

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