Dysrythmias - Cardiac Cell Types \u2022 Pacemaker Cells \u2022 Myocardial Cells Myocardial Cells Primary Function \u2022 Contraction and relaxation Primary

Dysrythmias - Cardiac Cell Types • Pacemaker Cells •...

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Cardiac Cell Types • Pacemaker Cells • Myocardial Cells Myocardial Cells Primary Function Contraction and relaxation Primary property Contractility Pacemaker Cells Specialized pacemaker cells in the sinoatrial node normally determine the overall rate of contractions • The central nervous system does not directly create the impulses to contact the heart, but only sends signals to speed up or slow down the heart rate through the autonomic nervous system using two modes: (1) sympathetic (stress) and (2) parasympathetic system Pacemaker Cells • Primary functions • Generation and conduction of electrical impulses. Primary properties • Automaticity • Contractility Pacemaker Cells • Parasympathetic (restful) modulation, rather than controlling each beat. Pacemaker Cells • 1. Sinoatrial Node (SA) is located in the right atrium at the epicardinal surface.( Primary) • 2. Atrioventricular Junctional area lies just beneath the right atrial endocardium close to the tricuspid valve. • 3. Bundle Branch system extends
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down the left and right ventricles. Properties of Cardiac Cells AUTOMATICITY : Ability of cardiac cells to spontaneously initiate an electrical impulse. EXCITABILITY or IRRITABILITY: A characteristic shared by all cardiac cells that refers to the ability of cardiac muscle cells which are electrically irritable, to respond to electrical impulse because of ionic imbalance. CONDUCTIVITY : The ability of cardiac cells to receive and transmit electrical stimuli from one cell membrane to an adjacent cell member CONTRACTILITY
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