On the Motion of the Heart and Blood in Animals

Harvey presented his revolutionary theory of blood circulation which challenged the prevailing Galenic view that had dominated medical thought for centuries. The Galenic view suggested that blood was produced in the liver and then consumed by the bodys organs. Harveys observations and experiments led him to propose a different model: Theory of Circulation: Harvey proposed that blood circulated continuously through the body in a closed system. He described the heart as a pump that drives the circulation of blood through a network of arteries and veins. Function of the Heart and Valves: Harvey explained that the hearts contraction (systole) and relaxation (diastole) drove the movement of blood. He also described the function of heart valves which prevented the backward flow of blood. Evidence from Experimentation: Harvey supported his theory with extensive observations and experiments on animals and humans. He demonstrated the one-way flow of blood and provided evidence that the hearts contraction was responsible for its movement. Capillaries: Harvey proposed the existence of tiny vessels (capillaries) connecting arteries and veins allowing the exchange of nutrients and waste products between blood and tissues.