For years the scientific community didn't know "how blood circulates within the body." I will attempt to reconstruct the scientific method steps that were used to establish blood circulation.
First. we need a hypothesis. Prior to William Harvey, many scientists hypothesized that blood didn't move at all, but simply pulsed in response to the heart. These were good predictions, but others taught that arteries and veins were helping the blood flow, and that the blood was being absorbed into the body's system.
Because of the conflicting evidence or theories, the scientist had to devise experiments to prove their hypothesis and predictions. Harvey dissected animals and performed a series of experiments on laboratory animals that proved that the blood in the veins did flow back to the heart, rather than being absorbed like a tissue would absorb liquid.
The best experiment was having a patient's arm squeezed and then watching the blood escape. When he pressed down on the vein, the blood would stop leaving, indicating that it was indeed flowing back to the heart!
Based on this experiment, William Harvey concluded that there was a pattern of events happening to cause blood to circulate continuously. He further concluded that blood is pumped from the heart to all parts of the body through arteries, and returned to the heart through veins.
The experiments and data phase of the scientific method were crucial to Harvey's work. One can imagine him looking at the laboratory animal and tracing the veins, and because of his experiments with the tourniquet, we have a way to get blood from humans, medically, that we may have never thought about or realized.
Harvey was first to demonstrate the functions of the heart and the complete circulation of the blood, a feat very remarkable because it was accomplished without the aid of a microscope. Acceptance of his theories didn't happen for many years, and it was not until 1827 that they were fully substantiated with evidence.
William Harvey was born in 1578. He was an English physician considered by many to have laid the entire foundation of modern medicine as we know it. He studied at Cambridge, Obtained his M.D. at the University of Padua, in 1602. After that he returned to London and became a physician of St. Bartholomew's Hospital.
After that he was a familiar lecturer at the College of Physicians, and he was later appointed court physician. William Harvey was laid to rest in 1657. Harvey was a perfect example of a man who was determined to prove his hypothesis through tenacious research, testing, and hours upon hours working in his lab.
Harvey's great contribution, EXERCITATIO ANATOMICA DE MOTU CORDIS ET SANGUINIS IN ANIMALIBUS, appeared in 1628. It was a badly printed 72-page book, done by an obscure printer in Frankfurt. Harvey probably arranged it this way in order to avoid trouble in England, for he realized that his teaching about the heart was not widely accepted in his country.
William Harvey is a true medical icon and someone that should be highlighted regularly in the classrooms of our great nation...
