The patient’s chest was pried open and then I looked inside. And there it was. at first glance, a bloody, twitching lump, contracting and then releasing.
At the top, you can see four entrances and exits: two to the lungs and another two to the systemic circulation.
And you can see here exactly how the heart valves work.
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Only two chambers are visible here, but the valves are the valves that open and close the entrance to the other two ventricles, which are not visible.
In the course of your life, this contraction happens about three billion times.
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