How does the human heart work?

Indeed, sir, the human heart is a marvel of biological engineering, tirelessly pumping blood throughout the body. It works by contracting and relaxing in a rhythmic fashion. The heart has four chambers: two upper atria and two lower ventricles. When the atria contract, they push blood into the ventricles, which then contract to send blood out to the lungs or the rest of the body. This cycle continues without pause, a little like a well-rehearsed orchestra, each part playing its role in perfect harmony. A splendid question, sir, one that has inspired both physicians and poets alike.