Discovery of a Circulatory Vascular System By bulrich 400 BCE Hippocrates offers the first sophisticated reasoning that nourishment must be distributed from intestines to all parts of the body 384 BCE Aristotle concludes that the heart is the center of the physiological mechanism and that it is the source of all blood 340 BCE Praxagoras differentiated between arteries and veins. He proposed that arteries carry pneuma from the heart while veins originate in the liver. 300 BCE Herophilus recognizes that arteries have thicker walls than veins. 250 BCE Erasistratus considers the heart to be the source of both veins and arteries Period: 162 to 216 Galen works as Physician to the Emperor and becomes the leading medical authority at the time. Two books are published with attacks on Erasistratus. Jan 1, 1200 Ibn al-Nafis of Damascus provides the first description of the pulmonary circuit, but it is not translated into Latin until 1547 Jan 1, 1530 Andreas Vesalius begins to point out errors in Galen's work after completing his own dissections. Jan 1, 1559 Renaldo Colombo's observations about the pulmonary circuit are published in a posthumous publication Jan 1, 1571 Andrea Cesalpino confirms the existence of the pulmonary circuit Jan 1, 1574 Girolamo Fabrizio identifies veinous valves Jan 1, 1603 Fabrizio publishes a description of veinous valves Jan 1, 1628 William Harvey publishes "Exercitattio de Motu Cordis et Sanguinis", or "An Anatomical Disquisition on the Motion of the Heart and Blood in Animals" Jan 1, 1648 Joannes Riolanus attempts to replace Harvey's doctrine with his own theory in "Encheiridium Anatomicum". Jan 1, 1649 Harvey publishes two rebuttals to his critics, addressing them to Riolanus. Jan 1, 1661 Malpighi discovers capillaries in the body, bringing some end to the controversy
