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Toward a definition of “pathological process” Richard H. Scheuermann, Ph.D. Professor of Pathology Director of Biomedical Informatics U.T. Southwestern Medical Center

Toward a definition of “pathological process” Richard H. Scheuermann, Ph.D. Professor of Pathology Director of Biomedical Informatics U.T. Southwestern

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Page 1: Toward a definition of “pathological process” Richard H. Scheuermann, Ph.D. Professor of Pathology Director of Biomedical Informatics U.T. Southwestern

Toward a definition of “pathological process”

Richard H. Scheuermann, Ph.D.

Professor of Pathology

Director of Biomedical Informatics

U.T. Southwestern Medical Center

Page 2: Toward a definition of “pathological process” Richard H. Scheuermann, Ph.D. Professor of Pathology Director of Biomedical Informatics U.T. Southwestern

Foundational Definitions in OGMS

• Disorder =def. – A causally relatively isolated combination of physical components that is (a) clinically abnormal and (b) maximal, in the sense that it is not a part of some larger such combination.

• Disease =def. – A disposition (i) to undergo pathological processes that (ii) exists in an organism because of one or more disorders in that organism.

• Pathological Process =def. – A bodily process that is a manifestation of a disorder.

Page 3: Toward a definition of “pathological process” Richard H. Scheuermann, Ph.D. Professor of Pathology Director of Biomedical Informatics U.T. Southwestern

Homeostasis

• We use ‘homeostasis’ to designate a disposition of the whole organism (or of some causally relatively isolated part of the organism, such as a single cell) to regulate its bodily processes in such a way as– (1) to maintain bodily qualities within a certain range or profile, and– (2) to respond successfully to departures from this range caused by internal

influences or environmental influences such as poisoning.

• When bodily processes yield qualities outside the range of homeostasis, then the organism initiates processes designed to return the qualities to a value within this range.

• In some cases, homeostasis can be lost and then re-gained at a level that is clinically abnormal, for example in the case of adaptation to major injury.

• In other cases the organism will pass a point where it falls irreversibly outside the realm of homeostasis.

Page 4: Toward a definition of “pathological process” Richard H. Scheuermann, Ph.D. Professor of Pathology Director of Biomedical Informatics U.T. Southwestern

time

state homeostaticrange

homeostaticset point

physiologicalstate

Normal Physiological Homeostasis

Page 5: Toward a definition of “pathological process” Richard H. Scheuermann, Ph.D. Professor of Pathology Director of Biomedical Informatics U.T. Southwestern

Normal Physiological Homeostasis

time

state

infant

child

adultelderly

Page 6: Toward a definition of “pathological process” Richard H. Scheuermann, Ph.D. Professor of Pathology Director of Biomedical Informatics U.T. Southwestern

Dependencies

• Age• Gender• Genetic background• Diet• Environment• Microbiome

Page 7: Toward a definition of “pathological process” Richard H. Scheuermann, Ph.D. Professor of Pathology Director of Biomedical Informatics U.T. Southwestern

Chronic Disease

time

state

etiological event

Page 8: Toward a definition of “pathological process” Richard H. Scheuermann, Ph.D. Professor of Pathology Director of Biomedical Informatics U.T. Southwestern

Acute Disease

time

state

etiological event

disease resolution

Page 9: Toward a definition of “pathological process” Richard H. Scheuermann, Ph.D. Professor of Pathology Director of Biomedical Informatics U.T. Southwestern

Progressive Disease

time

state

etiological event

Page 10: Toward a definition of “pathological process” Richard H. Scheuermann, Ph.D. Professor of Pathology Director of Biomedical Informatics U.T. Southwestern

Normal Adaptation

time

state

environment change

Page 11: Toward a definition of “pathological process” Richard H. Scheuermann, Ph.D. Professor of Pathology Director of Biomedical Informatics U.T. Southwestern

Definitions

time

state homeostaticrange

homeostaticset point

physiologicalstate

• Homeostatic set point – the ideal state of a bodily system in a given context.

• Normal homeostatic range – the set of states of a bodily system considered to be clinically normal.

• Physiological process – a bodily process that changes the state of a bodily system such that it approaches (moves closer to) the homeostatic set point.

• Pathological process – a bodily process that changes the state of a bodily system away from the normal homeostatic range.