Lect19 - Feb1 - cardio II

Lect19 - Feb1 - cardio II - specialized cells - important...

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4 CV 4 Specialized Cells and Structures within the Heart Specialized Cells – cells with differing properties and functions Muscle Cells – Contractile Proteins & Generate Pressure. Atria & Ventricles Pacemaker Cells – Self Depolarize and Initiate Activation Heart Purkinje Fibers – Cells Specialized for Rapid Conduction Cells in AV Node – Slow Rate of Rise and Low Amplitude ! slow cell to cell spread of activation. Specialized Structures within the Heart SA Node – Activation normally originates from Pacemaker Cells Localized here. Internodal and Interatrial Preferential Conduction Pathways AV Node – Site conduction delay in atrioventricular activation. Filter atrial arrythymias from ventricles. Contains some Pacemaker Cells. His Bundle & Bundle Branch System – Composed of Purkinje Fibers. Specialized Ventricular Conducting System. – Purkinje Fibers can develop pacemaker activity. Figure 9-8 specialized cells - important for spread of activation through the heart. Cardiac muscle cells are myogenic (can self depolarize), no neural input needed. spread of activation throug hthe atria to the AV node. Conduction throug hte AV node is quite slow - 80-90% of time delay attributed to AV node. Also is a very small structure, cells have a slow rate of rise and low amplitude of AP. purkinje Fbers - no contractile proteins, specialized for conduction. Have the fastest rate of rise and highest amplitude AP HB/BB - specialized for synchronization of activation of muscle cells in the ventricles. Can live with atrial Fbrilation becasue the AV node Flters out some of the signals.
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January 20, 2011 5 CV 5 Topic 2: Cardiac Electrophysiology Chapter 9 Outline 1. Myogenicity of Vertebrate Heart 2. Action Potentials from Regions of the Heart 3. Ion Channel Activation & Generation of the Cardiac Action Potential – Purkinje Fiber & SA Nodal Pacemaker Cell 4. Sequence of Activation of the Heart – timing function of capacity of one group of cells to generate action potentials in the adjacent cells.
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Lect19 - Feb1 - cardio II - specialized cells - important...

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