title: A physiologist's view of homeostasis.
abstract: Homeostasis is a core concept necessary for understanding the many regulatory mechanisms in physiology. Claude Bernard originally proposed the concept of the constancy of the "milieu interieur," but his discussion was rather abstract. Walter Cannon introduced the term "homeostasis" and expanded Bernard's notion of "constancy" of the internal environment in an explicit and concrete way. In the 1960s, homeostatic regulatory mechanisms in physiology began to be described as discrete processes following the application of engineering control system analysis to physiological systems. Unfortunately, many undergraduate texts continue to highlight abstract aspects of the concept rather than emphasizing a general model that can be specifically and comprehensively applied to all homeostatic mechanisms. As a result, students and instructors alike often fail to develop a clear, concise model with which to think about such systems. In this article, we present a standard model for homeostatic mechanisms to be used at the undergraduate level. We discuss common sources of confusion ("sticky points") that arise from inconsistencies in vocabulary and illustrations found in popular undergraduate texts. Finally, we propose a simplified model and vocabulary set for helping undergraduate students build effective mental models of homeostatic regulation in physiological systems.
authors.affiliation: Physiology Educational Research Consortium, Seattle, Washington; modell@physiologyeducation.org.
authors.forename: Harold
authors.initials: H
authors.lastname: Modell
authors.affiliation: Department of Biology, Niagara University, Niagara, New York;
authors.forename: William
authors.initials: W
authors.lastname: Cliff
authors.affiliation: Department of Molecular Biophysics and Physiology, Rush Medical College, Chicago, Illinois;
authors.forename: Joel
authors.initials: J
authors.lastname: Michael
authors.affiliation: Department of Biology, Edmonds Community College, Lynnwood, Washington;
authors.forename: Jenny
authors.initials: J
authors.lastname: McFarland
authors.affiliation: Department of Biology, University of Washington, Seattle, Washington; and.
authors.forename: Mary Pat
authors.initials: MP
authors.lastname: Wenderoth
authors.affiliation: Department of Biology, Canisius College, Buffalo, New York.
authors.forename: Ann
authors.initials: A
authors.lastname: Wright
mesh_terms: D000818:Animals; D032882:Comprehension; D032921:Consensus; D003479:Curriculum; D004517:Education, Professional / Q000266:history / Q000379:methods* / Q000592:standards; D049673:History, 20th Century; D049674:History, 21st Century; D006706:Homeostasis; D006801:Humans; D007858:Learning; D008954:Models, Biological; D010827:Physiology / Q000145:classification* / Q000193:education* / Q000266:history / Q000592:standards; D013663:Teaching / Q000266:history / Q000379:methods* / Q000592:standards; D009626:Terminology as Topic
keywords: core concepts; homeostasis; negative feedback; regulation