On following this debate it would appear that the real 'myth' (and one that
is readily apparent in medicine and healthcare) is that phenomena such as
homeostasis exist in a dichotomous classification system (i.e. an organism
achieves homeostasis or doesn't achieve homeostasis) whilst in fact this is
not true, especially for most (but not all) biological phenomena.
The 'true' classification and most appropriate method to interpret such
phenomena is that of a continuum where in fact a range of values together
constitute a biological event or process. This is clearly seen with the
classic example of blood pressure where blood pressure is not achieved or
not achieved (i.e. it is not a single categorical entity) but a range of
values that merge into the entity we know as blood pressure and arbitrarily
classify as normotensive, hypotensive or hypertensive. This concept is
explained with far more clarity by the writings of George Pickering in the
1950's although this concept still proves difficult for clinicians to accept
and incorporate into practice.
An obvious question that arises is whether classification error is
important? Logically it is important however it is not easily incorporated
into the world that most of us believe or at least wish for. This is the
world of clear, simple categorical outcomes, reducing complex problems into
black and white, those that have disease versus those that have not, those
with high blood pressure versus those with low or normal blood pressure,
etc. …
With respect to the homeostasis debate on this list it is apparent that this
misclassification, or perhaps misinterpretation, of this issue has been
constant since the first posting. This argued that 'plenty of research and
clinical findings' (although none specifically is quoted) has been unable to
substantiate the 'myth' that a perfect state of precise homeostasis can be
achieved. If seeking a dichotomous 'have' versus 'have not' situation then
this can be readily believed however this would be an erroneous
interpretation of the biological process of homeostasis and on further
inspection most reputable books and scientific journal articles expound
this.
A further, and perhaps more serious, misunderstanding appears to result from
the interpretation of the "likelihood of breakdown increases markedly (e.g.
heart attacks) when systems approach harmony". Is this arguing that heart
attacks are more frequent on an individual basis or population basis with
respect to homeostasis? Biological data (such as heart attacks) which are
normally distributed with the classic bell shape distribution provide a good
platform on which to clarify the potential misunderstanding above:
Although risk of a heart attack for an INDIVIDUAL may be relatively low in
the centre of the distribution, the cumulative POPULATION risk (and number
of actual events) is much higher in the middle. This is because there are
far more people with a small individual risk (i.e. the majority) in the
centre of the distribution than there are people with a high individual risk
at the ends or tails of the distribution (i.e. the minority).
Continuation of life certainly is about correction, adaptation and
compensation; distribution is important because nature doesn't appear to
favour those at the extremes of a distribution. A pertinent example is
infants of either low or high birth-weight (i.e. the minority) where excess
mortality is greater compared to infants with birth-weights towards the
middle of the distribution (i.e. the majority); of course commonly termed
survival of the fittest.
Perhaps the conclusion of the first email of this debate (dinosaurs from
outdated science of the past) could be appropriately revised?
Alistair Grant
Institute of Public Health
University of Cambridge
>From: "Stanislav A. Korobov" <[log in to unmask]>
>Reply-To: PHYSIO - for physiotherapists in education and practice
> <[log in to unmask]>
>To: [log in to unmask]
>Subject: Re: The Myth of Homeostasis
>Date: Thu, 11 Jan 2001 21:47:34 +0000
>
>TO: Marco Schuurmans Stekhoven <[log in to unmask]>
>
>Dear Marco, thank you. I think you found very correct words --
>"physiological balance". Most likely, I kept them in mind when was writing
>about homeostasis.
>
>The "balance" word has, as I know, two main senses in English: (1) a
>weighing tool; (2) an equilibrium. Probably, "physiological balance" in the
>former sense is simply our organism keen to a maximally possible
>homeostasis, and equilibrating its own defensive/compensatory potentials
>with potentially dangerous disturbances. In the second sense,
>"physiological
>balance" is a state of relative equilibrium between dangerous (for the
>organism) and defensive/compensatory processes. This equilibrium is
>relative
>but relatively steady. And it is homeostasis.
>
>This equilibrium is not, of course, something absolute and unchangable.
>Both
>bowls of the organism's weigher are not nailed to the table! They are
>constantly oscillating but the weigher's indicator is constantly tending to
>zero (if the organism has yet compensatory potentials; we do not consider
>here cases from reanimation practice).
>
>I think the above "theoretical" considerations have direct relation to
>organisms of our patients. They all have a definite state of homeostasis:
>one state is relatively worse, another state -- relatively better...
>Anyhow,
>we must remember that a maximally possible homeostasis is the most steady
>state of the body. Accordingly -- the most healthy (the case of death
>steady
>state is certainly out of our consideration). Consequently, we must simply
>drag our patient to his/her optimal homeostasis.
>
>All the best. And my apologies to those readers who tend to sleep reading
>this.
>
>Stanislav.
>
>Stanislav A. Korobov, MD, PhD
>Physician-Physiotherapist
>P.O.Box 7, Odessa, 65089, Ukraine
>[log in to unmask]
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