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 thin myofilaments and cross bridge cycle k Turning contraction of i Ca2 pumped out of sarcopasm via Ca2 pumps ii Myosin phosphatase dephosphorylates myosin light chains The Heart Circulatory System Chapter 13 1 2 3 4 5 6 7 8 Right atrium Right ventricle Left atrium Left ventricle Atria separated by interatrial septum Ventricles separated by interventricular septum Fibrous skeleton band of connective tissue in walls of ventricles and valves Valves prevent backflow a AV valves i R tricuspid ii L bicuspid iii Flaps are connective tissue iv Underside connected to connective tissue fibers chordae tenineae other end connects to papillary muscles in ventricle v This holds the valve in place so they don t open the other way during contraction vi Murmurs 1 Backflow due to damaged valve 2 Caused by streptococcus pyrogenase antibodies for strep attach to connective tissues in body causing destruction of those cells 3 Don t class all the way incompetent

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