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Depolarization is essential to the function of many cells, communication between cells, and the overall physiology of an organism. Action potential in a neuron, showing depolarization, in which the cell's internal charge becomes less negative (more positive), and repolarization, where the internal charge returns to a more negative value.
The P wave is a summation wave generated by the depolarization front as it transits the atria. Normally the right atrium depolarizes slightly earlier than left atrium since the depolarization wave originates in the sinoatrial node, in the high right atrium and then travels to and through the left atrium.
The ECG will show a terminal R wave in lead V1 and a slurred S wave in lead I. Left bundle branch block widens the entire QRS, and in most cases shifts the heart's electrical axis to the left. The ECG will show a QS or rS complex in lead V1 and a monophasic R wave in lead I.
The action potential of a ventricular myocyte. In electrocardiography, the ventricular cardiomyocyte membrane potential is about −90 mV at rest, [1] which is close to the potassium reversal potential. When an action potential is generated, the membrane potential rises above this level in five distinct phases. [1]
Different wave shapes generated by different parts of the heart's action potential The ECG complex. P=P wave, PR=PR interval, QRS=QRS complex, QT=QT interval, ST=ST segment, T=T wave Principle of ECG formation. The red lines represent the depolarization wave, not bloodflow. An electrocardiogram is a recording of the electrical activity of the ...
The QRS complex is the combination of three of the graphical deflections seen on a typical electrocardiogram (ECG or EKG). It is usually the central and most visually obvious part of the tracing. It corresponds to the depolarization of the right and left ventricles of the heart and contraction of the large ventricular muscles.
[1] [2] This means that all atrial cells can contract together, and then all ventricular cells. Different shapes of the cardiac action potential in various parts of the heart Rate dependence of the action potential is a fundamental property of cardiac cells and alterations can lead to severe cardiac diseases including cardiac arrhythmia and ...
Electrical waves track a systole (a contraction) of the heart. The end-point of the P wave depolarization is the start-point of the atrial stage of systole. The ventricular stage of systole begins at the R peak of the QRS wave complex; the T wave indicates the end of ventricular contraction, after which ventricular relaxation (ventricular diastole) begins.