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Anoxic depolarization is a progressive and uncontrollable depolarization of neurons during stroke or brain ischemia in which there is an inadequate supply of blood to the brain. [1] Anoxic depolarization is induced by the loss of neuronal selective membrane permeability and the ion gradients across the membrane that are needed to support ...
P-wave changes in left and right atrial hypertrophy. Bifid P waves (known as P mitrale) indicate left-atrial abnormality - e.g. dilatation [6] or hypertrophy. [1] If at least three different shaped P waves can be seen in a given ECG lead tracing, this implies that even if one of them arises from the SA node, at least two others are arising ...
The most obvious abnormal finding will be abnormal P waves. One of three options can occur: [12] 1. There are no P waves. This is because of either failure of retrograde flow to the atria or the P wave is hidden in the QRS. If the P wave is hidden that implies the atria depolarize at the same time as the ventricles. 2.
In contrast, that same depolarization would produce minimal deflection in V 1 and V 2 because the vectors are perpendicular, and this phenomenon is called isoelectric. Normal rhythm produces four entities – a P wave, a QRS complex, a T wave, and a U wave – that each have a fairly unique pattern. The P wave represents atrial depolarization.
The process of depolarization is entirely dependent upon the intrinsic electrical nature of most cells. When a cell is at rest, the cell maintains what is known as a resting potential. The resting potential generated by nearly all cells results in the interior of the cell having a negative charge compared to the exterior of the cell.
This is the property of the AV node that prevents rapid conduction to the ventricle in cases of rapid atrial rhythms, such as atrial fibrillation or atrial flutter. The AV node's normal intrinsic firing rate without stimulation (such as that from the SA node) is 40–60 times/minute. [ 13 ]
The excitatory neurotransmitters, the most common of which is glutamate, then migrate via diffusion to the dendritic spine of the postsynaptic neuron and bind a specific transmembrane receptor protein that triggers the depolarization of that cell. [1] Depolarization, a deviation from a neuron's resting membrane potential towards its threshold ...
The two bundle branches taper out to produce numerous Purkinje fibers, which stimulate individual groups of myocardial cells to contract. [5] The spread of electrical activity through the ventricular myocardium produces the QRS complex on the ECG. Atrial repolarization occurs and is masked during the QRS complex by ventricular depolarization on ...