The Artful Heart
As the prohibition against human dissection was abandoned in the Renaissance era, knowledge of anatomy and the heart grew significantly. Fascination with the heart led the artist and inventor Leonardo da Vinci (1452-1519) to create models and numerous finely detailed drawings of the organ. Da Vinci was one of many Renaissance artists who used dissection of the dead as a tool in the understanding of human life. His drawings clearly show the way the heart works as a pump and document the changes of aging blood vessels. But Da Vinci's drawings had little influence on contemporary medicine because they were held privately and were not seen by many physicians.
Andreas Vesalius (1514-1564) was far more influential among healers. His classic physiology text featured the first accurate descriptions and drawings of the heart to be publicized. Vesalius also challenged Galen's "hidden passage" idea, arguing that this was not possible given the physiology of the heart. His description of autopsy
reports revealed increasing understanding of the diversity of heart problems. One report described a huge mass of flesh in the left ventricle of a man's heart that weighed almost two pounds. Such an obstruction is known by contemporary physicians as a thrombus, a mass of blood tissue which can block blood vessels.
Another great influence in the development of knowledge about the heart was William Harvey (1578-1657), a physician whose findings about the blood and the circulatory system changed medicine profoundly. He was the first to show that blood traveled in a circle through the body. Harvey also understood the rhythmic nature of the heart's work. His work described the way blood was expelled from the heart with each contraction and entered the heart with every relaxation.
Though Harvey revealed the principles of blood circulation, he and his contemporaries did not understand the purpose of the lungs in the circulatory system. True understanding about the functioning of the lungs did not occur until the nineteenth century, when knowledge of chemistry advanced and researchers gained knowledge about the lungs' role in oxygenating blood for the tissues of the body.