Milieu intérieur or interior milieu, from the French, milieu de l’intérieur, (the environment within) is a term coined by Claude Bernard to refer to the extra-cellular fluid environment, and its physiological capacity to ensure protective stability for the tissues and organs of multicellular living organisms.

Contents 1 Origin 2 Early reception 3 Conceptual development 4 Notes

[edit] Origin

Claude Bernard used the term in several works from 1854 until his death in 1878. He probably adopted it from the histologist Charles Robin, who had employed the phrase “milieu de l’intérieur” as a synonym for the ancient hippocratic idea of humors. Bernard was initially only concerned with the role of the blood but he later included that of the whole body in ensuring this internal stability.^[1] He summed up his idea as follows:

The fixity of the milieu supposes a perfection of the organism such that the external variations are at each instant compensated for and equilibrated.... All of the vital mechanisms, however varied they may be, have always one goal, to maintain the uniformity of the conditions of life in the internal environment .... The stability of the internal environment is the condition for the free and independent life. ^[2]

[edit] Early reception

Bernard’s idea was initially ignored in the nineteenth century. This happened in spite of Bernard being highly honored as the founder of modern physiology (he indeed received the first French state funeral for a scientist). Even the 1911 edition of Encyclopedia Britannica does not mention it. His ideas about milieu interieur only became central to the understanding of physiology in the early part of the twentieth century.^[1] It was only with Joseph Barcroft, Joseph Henderson, and particularly Walter Cannon and his idea of homeostasis that it received its present recognition and status.^[3] The current 15th edition notes it as being Bernard's most important idea.

[edit] Conceptual development

Bernard created his concept to replace the ancient idea of life forces with that of mechanistic process in which the body's physiology was regulated through multiple mechanical equilibrium adjustment feedbacks.^[3] Walter Cannon's later notion of homeostasis (while also mechanistic) lacked this concern, and was even advocated in the context of such ancient notions as vis medicatrix naturae.^[3]

Cannon, in contrast to Bernard, saw the self-regulation of the body as a requirement for the evolutionary emergence and exercise of intelligence, and further placed the idea in a political context: "What corresponds in a nation to the internal environment of the body? The closest analogue appears to be the whole intricate system of production and distribution of merchandise".^[4] He suggested that on analogy to body's own ability to ensure internal stability that society should preserve itself with a technocratic bureaucracy, "biocracy".^[3]

The idea of milieu intérieur, it has been noted, led Norbert Wiener to the notion of cybernetics and negative feedback creating self-regulation in the nervous system and in nonliving machines, and that "today, cybernetics, a formalization of Bernard’s constancy hypothesis, is viewed as one of critical antecedents of contemporary cognitive science".^[1]

[edit] Notes