Monthly Archives: October 2000

Harvey and the circulation of Blood

 

      The circling streams once thought but pools of blood

      Whether life’s food or body’s fuel

      From dark oblivion Harvey’s name shall save

 

                              – Dryden

 

      Around the same time when Newton was making his making his mathematical theories and Shakesphere was writing his great tragedies , there was another man in England who was making some breakthrough theories in the field of Madicine . His name was William Harvey .

      At that time all we know about the circulation of blood in our body was from the theories of Galen,the Greek physician who lived in the 2nd century He dissected the body and made the first theories of blood formation and how it flows in the body .

      Before Harvey people believed that food was converted to blood in the liver and blood is the food for various organs in the body . The role of the heart was unclear .

 

      Harvey was born in Folkeston in 1578 . He graduated to become a physician from Cambridge University . He then went to Padua University in Italy for further study of medicine . Here he studied the theories of Galen . In 1604 he returned to England and started practicing as a doctor .

In 1615 he bacame a lecturer in surgury . This position required Harvey to do various public dissections . It was during this time that he started stating his theories about the circulation of blood .

      His methods were different . He didnt start with the human body .

He believed that in order to understand how complex systems behaved it is first important to study simpler creatures . So he started studying frogs , snails , lobsters etc . He found that all blood vessels start from the heart . Also all blood vessels pass thru the lungs . So he was the first to say that the heart is the “machine” that pumps blood into the body . He considered the heart to be a muscle the contraction of which pushes blood in the artries . He was the first to show that blood goes to different parts thru the artries and comes back through the veins .

So the circulatory system is a circular one way path . He disproved Galen’s throry that veins take blood to the different parts of the body .

This he showed by observing the valves in the veins and in which direction they open .

      Of course some of his theories were wrong too . He tried to make a theory which could explain the difference in color of the blood in the veins and the artries . But he was wrong . The actual theory came after oxidation was discovered .

      He published his theories in 1628 in ” An Anatomical study of the Motion of Heart and Blood in ANimals ” . His theories met with stiff resistance . One of his opponents ( Hoffman ) said that if Harvey’s theories are to be believed then that would mean that there are 2 kinds of blood ( pure and impure ) . But how can this be true . Nature prefers simplicity . Then there were others who tried to invoke religious huga – buga ! But all in vain ( artery ?! ) . Harvey had answers to all their issues .

      His theories are now an integral part of Madicine . He was the first person after Galen to make a good theory about blood circulation because he believed in experimenting and not just thinking about what should be the truth . This method of experimentation was what started the Scientific revolution .

      After his research on blood circulation he made some discoveries in embryology . His research in this area proved the basis for modern theories in this area .

 

      He died in 1657 .