Blood Circulation 400 Years after its Discovery

INTRODUCTION Modern medical science was born in the Post-Renaissance or counter-reformation era and began to consolidate in the mid-seventeenth century thanks to the work of physicists, physiologists and biologists who were direct or indirect disciples of Galileo. At that time there was a tendency for scientific studies to move away from conservative and traditionalist universities to concentrate in groups of private researchers. Thus the first scientific academies were created, the “Lincean” (Lincei) Academy in Rome (1603), to which Galileo belonged since 1610, and later the Royal Society in London. In turn, authors began to publish their scientific writings in their national languages. We owe cardiovascular physiology to the studies of the English doctor William Harvey, who was able to combine some previous anatomical observations with the first quantitative medical experiments he performed. His great discovery was to show that the heart sends the blood to the whole body and that it returns in its entirety to the heart in a closed circuit, a process that takes place continually and with all the blood. This discovery is considered as the only advance in physiology of the early seventeenth century. But in addition to the importance of this discovery, Harvey pioneered another aspect: he was the initiator of the scientific method. He referred to genuine, unimagined experiments, which he furnished with irrefutable quantitative demonstrations. It has been fairly asserted that his discovery of blood circulation was the first adequate explanation of an organic process and the starting point of the path to experimental physiology. However, in his monograph on the generation of animals entitled “De generatione animalium”, published in 1651, along with some paragraphs where he shows his scientific reasoning, there are others with confusing, vague and capricious statements, remnants of the pre-scientific era of which the author had not completely departed. It can be affirmed, therefore, that modern medical science did not arise suddenly and globally, but was gradually structured from the middle of the seventeenth century following the path traced by William Harvey in the light of Galileo’s thought.