Man, Machine, and Homeostasis

James R. Munis

in Just Enough Physiology

Published on behalf of © Mayo Foundation for Medical Education and Research

Published in print December 2011 | ISBN: 9780199797790
Published online June 2012 | e-ISBN: 9780199929665 | DOI:

Series: Mayo Clinic Scientific Press

Man, Machine, and Homeostasis

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Physiologist Claude Bernard lived in a time when very little was known about the mechanisms underlying physiologic findings, and he had ample access to clues garnered from observing machines. Let's consider homeostasis (a concept championed by Bernard), an example for which an engineered machine shed light on a fundamental principle of physiology. Homeostasis is simply the tendency of the body to maintain important physiologic variables (eg, heart rate, blood pressure, PACO2) at constant, preset values. An example is a simplified mechanical governor that could be used to regulate the rotational speed of a steam engine shaft. ‘Autoregulate’ might be a more apt word because the governor performs without external help or guidance, provided it is designed and built properly. It doesn't take much imagination to see an analogy between the mechanical governor and the autonomic nervous system. Both maintain specific variables at a constant set point through a process of feedback loops.

Chapter.  1291 words.  Illustrated.

Subjects: Professional Development in Medicine

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