William Harvey and the Discovery of the Circulatory System

William Harvey and the Discovery of the Circulatory System

By Lisa Kerik

Biology 30; Unit 3, Chapter 10

It seems hard to believe there was really a time when we didn’t know the function of blood, the pathways it took and the force that propelled it to circulate. It is easy in the midst of all our knowledge and technology to forget those before us who established and paved the way for the knowledge we take for granted today. It took many
centuries and many scientists’ contributions to discover the numerous details of the circulation system. There were many contributions made in this area between the fifteenth and seventeenth centuries and it is important to remember that these discoveries were made without the use of any technological devices we have come to depend on today. The data gathered by the many scientists were generated by observations, dissections, and the writings and theories of others before them. It is important to remember that many discoveries may not have been possible if it had not been for the previous information presented before it. This presented information may not have always been correct, but it served as a prompt for further analysis and research. This brings us to William Harvey and his discovery of the circulatory system.

There were many scientists with their own theories on the function and purpose of the heart and blood before William Harvey’s discovery. Some of these scientists include famous historical figures such as Aristotle, Galen, and Fabrici, just to name a few. Aristotle believed that pulsations in the blood system were due to the respiratory process and that the heart just moved as a result of the same breathing process. In these days, there were no such things as pumps, and the heart was not believed to be a muscle so there was no way to discover its purpose yet. Another scientist, Galen, held strong beliefs in the area of the blood and heart. Galen held the same beliefs as Aristotle in regards to the pulsations of the body, but he also believed that the blood just ebbed and flowed at a leisurely rate and nourished the surrounding tissues. He did studies on the heart and believed that blood got from one side of the heart to the other by way of invisible holes in the septum. Galen was a very respected man in science, so many followed his teachings without question. Later, more researchers began seeing discrepancies in Galen’s theories. Fabrici did some research on the valves in veins in the body and realized they regulated the volume of blood in any given area and opposed the flow of blood in a particular direction. Although he was wrong about the direction of opposed blood flow, his discovery was still a valuable one. William Harvey studied the heart and blood movement and revolutionized thinking on heartbeat, pulse and blood movement. He concluded upon his dissections, demonstrations and studies of other scientists’ works, that the heartbeat propels the blood in a continuous circular motion. This is far from the long and firmly held beliefs of Galen in that the blood ebbs freely and the heart moves as a result of breathing. Acknowledging the work of his predecessors, Harvey clarified many details of the pulmonary system. He proved that it was the beat of the heart that caused the continuous motion of blood; from the heart to the arteries to the veins and back to the heart. It was because of this information that many questions could be answered such as why poisons from one area of the body affected the whole body such as rabies and snake bites and why topical medicines rubbed on the skin were absorbed and dispersed through out the body.

We can see through historical findings that it is difficult to give one scientist all the credit for a discovery, as each discovery depends on the correct and incorrect assumptions of those before. William Harvey is famous for being the first to correctly state the function, pathway, and purpose of the heart and blood but he couldn’t have done it without the information of those before him.

Questions

Are we safe to assume no other scientists discovered the circulatory system and function of the heart and blood before William Harvey did? Explain your answer.

What are some possible reasons a scientist in the fifteenth to seventeenth century would not want to come forward with a discovery?

Should the scientific community acknowledge and give credit to those scientists whose contributions lead up to a significant discovery? Explain your answer.

References:

Magner, Lois N. A History of the Life Sciences. Marcel Dekker, Inc. 1994. New York, New York. PP 108-124, 155.

Ritter, Robert John. Nelson Biology. Nelson Canada. 1993. Scarborough, Ontario. PP 245-246.

Internet References:

http://es.rice.edu/ES/humsoc/Galileo/Catalog/Files/harvey.html