cardiac_physiology - Nasser-Eddin M, Ph.D Electrophysiology...

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Unformatted text preview: Nasser-Eddin M, Ph.D Electrophysiology and biomechanics of the cardiovascular system: an overview OVERVIEW OVERVIEW Cardiovascular electrophysiology Cardiovascular biomechanics Atria Ventricles Introduction Introduction ARTERIES distribute blood from the heart VEINS bring blood back to the heart Introduction Introduction Electrophysiology Biomechanics Objectives: 1. Understand normal activation sequence, conduction velocities, and intrinsic pacemaker rates in the human heart 2. Understand the anatomical and physiological basis of the P wave, PR interval, QRS complex, ST segment, T waves, QT interval and U waves. Electrophysiology Biomechanics • An inherent and rhythmic electrical activity is the reason for the heart’s lifelong beat. • The primary function of cardiac myocytes is to contract. Electrical changes within the myocytes initiate this contraction. • Cardiac cells, like all living cells in the body, have an electrical potential across the cell membrane. If measurements are taken with a resting ventricular myocyte, a membrane potential of about –90 mV will be recorded. Outside: • Positive ions = Na + (+ a small [ ] of k+), Ca ++ • Negative ions = Cl- Inside: • Positive ions = K + (+ a small [ ] of Na + ) • Negative ions = Proteins and phosphates ions Small over-quantity of positive ions Small over-quantity of negative ions Concentrations of ions across the myocyte membrane: Electrophysiology Biomechanics Myocytes can answer to a stimulus (excitability). Reaction = Opening of sodium channels of the membrane Opened channel Closed Na channel Increase of + inside Decrease of + outside Electrophysiology Biomechanics Massive entry of Na + ==> Depolarization where the Na channels are opened- 90mV →- 60mV →- 50¡mV → ......
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This note was uploaded on 02/07/2011 for the course MECH 633 taught by Professor Mohammadnasserdine during the Spring '10 term at American University of Beirut.

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cardiac_physiology - Nasser-Eddin M, Ph.D Electrophysiology...

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