Lecture 5 - NPB113 Contractile Properties of Cardiac Muscle...

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1 January 21, 2010 NPB113 Contractile Properties of Cardiac Muscle 5-1 Outline Definition of terms and description of concepts. Model of sarcomere showing relationship among parallel and series elastic elements and contractile element in muscle contraction. Sequence of mechanical events in muscle contraction and the dissipation of contractile energy. Dissipation of contractile energy and affects on series elastic element, sarcomere length and whole muscle length for an isotonic muscle contraction. Dissipation of contractile energy and affects on series elastic element, sarcomere length and whole muscle length for an isometric contraction. Affect of load on sarcomere shortening and whole muscle length.
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2 January 21, 2010 NPB113 Contractile Properties of Cardiac Muscle 5-2 Outline, cont Length-Tension Relationship for cardiac muscle. Affect of muscle fiber length on calcium release and cross-bridge formation Force-Velocity Relationship – affect of load on rate of cross-bridge cycling and rate of whole muscle shortening. Affect of Muscle Fiber Length on tension development & on Force-Velocity Relationship. Po & Vmax Affect of Contractility on tension development and on Force-Velocity Relationship Po & Vmax
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3 January 21, 2010 NPB113 Contractile Properties of Heart Muscle 5-3 Definition of Terms for Understanding Contractile Properties of Cardiac Muscle and the Heart Preload portion of the total load on the muscle or heart that sets sarcomere length or the muscle fiber length. Portion of the total load acting on muscle prior to the onset of contraction. For the heart, it is the end diastolic volume . Afterload portion of the total load on the muscle that is met after the onset of contraction. Portion of the total load acting on muscle after contraction begins. For the heart, it is the aortic diastolic pressur e. Total Load = total load against which the muscle contracts or the whole heart pumps. Total Load = Preload + Afterload For the heart, Total Load = End Diastolic Volume (Preload) + Aortic Diastolic Pressure ( Afterload .)
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4 January 21, 2010 NPB113 Contractile Properties of Heart Muscle 5-4 Definition of Terms & Concepts, Cont Isotonic Contraction Contraction in which the whole muscle shortens externally and the muscle fibers shorten internally; sarcomere and external whole muscle shortens (whole muscle shortens and the load is moved). Isometric Contraction
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This note was uploaded on 04/09/2010 for the course NPB npb 113 taught by Professor Goldberg during the Spring '10 term at UC Davis.

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Lecture 5 - NPB113 Contractile Properties of Cardiac Muscle...

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