View full lesson: http://ed.ted.com/lessons/how-the-heart-actually-pumps-blood-edmond-hui For most of history, scientists weren't quite sure why our hearts were beating or even what purpose...
========== For most of history, humans had no idea what purpose the heart served. In fact, the organ so confused Leonardo da Vinci, that he gave up studying it. Although everyone could feel their own heart beating, it wasn't always clear what each thump was achieving. Now we know that the heart pumps blood. But that fact wasn't always obvious, because if a heart was exposed or taken out, the body would perish quickly. It's also impossible to see through the blood vessels, and even if that were possible, the blood itself is opaque, making it difficult to see the heart valves working. Even in the 21st century, only a few people in surgery teams have actually seen a working heart. Internet searches for heart function, point to crude models, diagrams ...