Search results
Results from the WOW.Com Content Network
The depolarization front is carried through the atria along semi-specialized conduction pathways including Bachmann's bundle resulting in uniform shaped waves. Depolarization originating elsewhere in the atria (atrial ectopics) result in P waves with a different morphology from normal.
Because the pacemaker potential represents the non-contracting time between heart beats , it is also called the diastolic depolarization. The amount of net inward current required to move the cell membrane potential during the pacemaker phase is extremely small, in the order of few pAs, but this net flux arises from time to time changing ...
The rapid depolarization of the cell, during phase 0, causes the membrane potential to approach sodium's equilibrium potential (i.e. the membrane potential at which sodium is no longer drawn into or out of the cell). As the membrane potential becomes more positive, the sodium channels then close and lock, this is known as the "inactivated" state.
The P wave represents depolarization of the atria. Atrial depolarization spreads from the SA node towards the AV node, and from the right atrium to the left atrium. The P wave is typically upright in most leads except for aVR; an unusual P wave axis (inverted in other leads) can indicate an ectopic atrial pacemaker. If the P wave is of ...
The SA node sends the depolarization wave to the atrioventricular (AV) node which—with about a 100 ms delay to let the atria finish contracting—then causes contraction in both ventricles, seen in the QRS wave. At the same time, the atria re-polarize and relax. The ventricles are re-polarized and relaxed at the T wave.
During ventricular systole the ventricles contract and vigorously pulse (or eject) two separated blood supplies from the heart—one to the lungs and one to all other body organs and systems—while the two atria relax (atrial diastole). This precise coordination ensures that blood is efficiently collected and circulated throughout the body.
Schematic representation of a normal sinus rhythm EKG wave. In electrocardiography, the PR interval is the period, measured in milliseconds, that extends from the beginning of the P wave (the onset of atrial depolarization) until the beginning of the QRS complex (the onset of ventricular depolarization); it is normally between 120 and 200 ms in duration.
This is the depolarization phase. When the membrane potential reaches the threshold potential (around -20 to -50 mV), the cell begins to rapidly depolarise (become more positive). [16] This is mainly due to the flow of Ca 2+ through L-type calcium channels, which are now fully open. During this stage, T-type calcium channels and HCN channels ...