CLAUDE BERNARD IS CALLED AS "FATHER OF MODERN PHYSIOLOGY"
The contribution of this great man, “Claude Bernard” to the field of physiology is enormous. He is a French physiologist and is rightly called as “Father of Modern Physiology”. His most important contribution to the field of physiology was his concept of the internal environment of the organism, which led to the present understanding of homeostasis—i.e., the self-regulation of vital processes. He is also known for his other discoveries which include discoveries concerning the role of the pancreas in digestion, the glycogenic function of the liver, and the regulation of the blood supply by the vasomotor nerves.
Early
days of Claude Bernard: Claude Bernard started teaching at his cottage
for local children at a very young age, when his father incurred huge
losses in his winegrowing business. His mother was from a peasant
background. After the death of his father, the entire responsibility
fell on his shoulders. Being from a winegrower background, the
educational opportunities were very scarce to him. Claude started his
schooling in the church school and his later education was done at
Jesuit College in Villefranche-sur-Saone. He showed a little academical
interest and was more interesting in making new friends at the school
Claude's parents were disappointed with his school performance and
arranged for him to spend a further year in the College Royal of
Thoissey. He became interested in philosophy, in particular by René
Descartes’ emphasis on the quest for truth stimulated by doubt. At that
time, his main interests were focused to Romantic writers, and he
himself wrote two books, a piece of vaudeville comedy (‘La Rose du
Rhône’) and a five-act historical tragedy (‘Arthur de Bretagne’). When
searching for an editor in Paris in 1834, one of them advises him to
abandon his projects for literature, and Claude Bernard began his
medical studies at the Faculty of Medicine of Paris. There, he shared a
lodging together with Charles Lassègue (the future prominent
neurologist).
Following
lectures by François Magendie, Professor of Experimental Medicine at
the Collège de France, he decided to devote his own life to experimental
physiology and, because of his skillful aptitudes, he was engaged by
Magendie in 1841 as a research assistant (préparateur). By deference to
the methodological approach and scientific interests of his mentor, his
first experimental studies were orientated towards the nervous system
and chemical aspects of digestion. During his whole life, Claude Bernard
will acknowledge Magendie’s positive influence on his own career. In
1843, Claude Bernard became a medical doctor but failed to qualify for
teaching medicine, and he had to work in the private laboratory of a
close friend.
Claude Bernard and Milieu interior:
The word “milieu interior” was coined by Claude Bernard. The literal
meaning of milieu interior in French is “environment within”. He
proposed that all the cells in our body is bathed in the ECF which acts
as the internal environment and all the activities of the cell depend on
the internal environment.
Scientific Discoveries by Claude Bernard
Among the discoveries made by Claude Bernard, the major ones were:
- Role of pancreas in digestion. Role of Liver in maintaining glucose homeostasis.
- Types of vasomotor nerves and their actions.
Pancreas experiment of Claude Bernard:
The
hypothesis at the time of Claude Bernard was that, the gastric and
pancreatic juice contain the same digestive principle. Claude wanted to
check the truthfulness of the above hypothesis. He created an artificial
pancreatic fistula in a dog and he further collected the pancreatic
juice. He found that gastric and pancreatic juice contained totally
different enzymes. Pancreatic juice contained a powerful enzyme which
could emulsify the fat which was absent in gastric juice.
Role of Liver in maintaining glucose homeostasis:
The
theory that was prevailing at the time of Claude Bernard was that, the
sugar was metabolized in the body particularly by the respiratory
system. He tried to identify the organ from which the sugar in the body
was disappearing. He starved few dogs and was assessing for glucose in
blood coming out of various organs. Surprisingly he found that blood
from the portal vein had a high amount of glucose, even though the dogs
were starving. He found that the sugar which was there in the blood was
actually the sugar which has come out of the liver. This concept has
helped us to understand the present functions of liver in glucose
homeostasis.
In
1855, by flushing with water the vessels from an isolated liver and by
leaving the organ for one night, he demonstrated that sugar was derived
from an unsolvable substance present in the hepatic tissue. He isolated
that substance in 1857, called it glycogen, and showed that is was
similar to starch.
Types of vasomotor nerves and their actions:
The
Third greatest discovery of claude Bernard was the two types of
vasomotor nerves. He found that there were two types of nerves,
vasodilatator nerves (which dilate the lumen of the blood vessel) and
vasoconstrictors (which shrink the lumen of the blood vessel).
All
of these discoveries of Claude Bernard astonished the physiologists
worldwide. Even in Germany, the Physiologist Du Bois-Reymond had to
acknowledge in 1860: “this discoverer, more lucky than anyone, now
forces everybody to look toward the vivisection table in the College of
France”.
Later
he was compelled to abandon his studies due to his illness and he wrote
a book “Introduction to the study of experimental medicine”. In this
book he establishes as general principles his thoughts about
experimentation in physiology and medicine. Bernard uses cases from his
own practice to illustrate experimental procedure and scientific
reasoning in medicine. He argues against custom and authority as guides
to sound decision-making, insisting that a theory disproved by
experiment must be abandoned forthwith. Bernard’s work becomes itself a
customary and authoritative guide to the provision of medical care.
Claude
Bernard occupied the seat 29 at the Académie française from 1868 and
was succeeded by Ernest Renan. When he died in 1878, he was accorded a
public funeral, an honor that had never before bestowed in France to a
man of science, and his grave resides in Père Lachaise cemetery in
Paris. He has been the father of a scientific revolution, and his
heritage is still active nowadays in parallel with the current genetic
revolution.