WITHOUT THE WORK OF WILLIAM HARVEY WE WOULD STILL BE LIVING IN A MAKE-BELIEVE WORLD WITH OUR BODIES

The discovery of blood circulation was described by an Egyptian centuries before any European reached the same conclusion. William Harvey (1578-1657) was both a physician and a remarkable natural historian. He was also the founder of modern physiology. His great achievement was the demonstration of circulation of the blood, a discovery which replaced centuries of theory and speculation, with knowledge firmly based on accurate observation and experiment. Harvey was born in Folkestone in Kent in 1578, the son of a yeoman. Harvey graduated MD in Padua in 1602 and returned to London. Harvey's monumental work "De Motu Cordis" was published in 1628.

Using experiments in animals such as the snake, he demonstrated that the blood passed from the veins to the right side of the heart (the right ventricle), and that the imagined pores in the septum of the heart did not exist; also that the right ventricle propelled the blood into the lungs. Then the blood returned to the left side of the heart. The left ventricle was thicker and more powerful than its counterpart on the right side, because it pumped blood, not just through the lungs, but throughout the entire body. Harvey clearly demonstrated that blood in the arteries was always carried away from the heart, and how the valves in the veins, originally described by his teacher Fabricius, ensured that the venous blood always flowed towards the heart. He calculated how much blood might be propelled from the heart with each heart beat and showed there was no likelihood that the liver could synthesize sufficient blood to enter the heart as proposed by the Galenists. From ingenious, but classically simple experiments and observations, Harvey concluded that the only explanation for the heart's action must be that a defined amount of blood constantly circulated throughout the body.

Dr. William Harvey shall always be revered for his pioneering work on our internal systems.