click on the video below to observe a beating heart
The next video gives a simple and clear explanation of the chambers, valves and heart sounds
This next video below shows how the atria and ventricles contract in relation to the valve sounds:
Finally, an excellent view from above showing how the systole and diastole synchronize together. The letters stand for valves: M is mitral, T is tricuspid, A is Aortic and P is pulmonary. where you see the word "squirt", it indicates ventricular contraction. Where you see "fill" is the atrial contraction.
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