Search results
Results from the WOW.Com Content Network
The endothelium that lines blood vessels is known as vascular endothelium, which is subject to and must withstand the forces of blood flow and blood pressure from the cardiovascular system. To withstand these cardiovascular forces, endothelial cells must simultaneously have a structure capable of withstanding the forces of circulation while ...
This system is especially significant ... The Bayliss effect in vascular smooth muscles cells is a ... (depolarization potentials spaced closely together in time so ...
Isolated heart conduction system showing atrioventricular node. The AV node receives two inputs from the right atrium: posteriorly, via the crista terminalis, and anteriorly, via the interatrial septum. [8] Contraction of heart muscle cells requires depolarization and repolarization of their cell membranes. Movement of ions across cell ...
The conduction system consists of specialized heart muscle cells, situated within the myocardium. [3] There is a skeleton of fibrous tissue that surrounds the conduction system which can be seen on an ECG. Dysfunction of the conduction system can cause irregular heart rhythms including rhythms that are too fast or too slow.
During frame 7, the depolarization is traveling through the largest amount of tissue in the atria, which creates the highest point in the P wave. Frames 11–12 depict the depolarization traveling through the AV node. Like the SA node, the AV node is too small for the depolarization of its tissue to be detected on most ECGs.
The pattern of prepotential or spontaneous depolarization, followed by rapid depolarization and repolarization just described, are seen in the SA node and a few other conductive cells in the heart. Since the SA node is the pacemaker, it reaches threshold faster than any other component of the conduction system.
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 plateau lasts on the order of 100 ms. At the time that calcium channels are getting activated, channels that mediate the transient outward potassium current open as well. This outward potassium current causes a small dip in membrane potential shortly after depolarization. This current is observed in human and dog action potentials, but not ...