Dynamic Homeostasis

[From Fred Nickols (980825.1805)]

Marc Abrams (980824.1102) responding to Jeff Vancouver 980824.1005 EST...

Again, be careful in your use of terms :slight_smile: Homeostasis
implies a system in equilibrium ( i.e. in a stable
unchanging state ) Control implies a _continuous_ mechanism
to _keep_ the system in a _desired_ state.

I buy "stable" Marc; I don't buy "unchanging." Indeed, I've always
thought that the notion of "homeostasis" conveys pretty clearly the
possibility that some kind of control system is in fact operating
because lots of things are changing yet the stability of the system
remains relatively intact (i.e., it doesn't go careening off "out of
control" as we laymen might say).

As my dictionary has it...

homeostasis: the tendency to maintain, or the maintenance of, normal,
internal stability in an organization by coordinated responses of the
organ systems that automatically compensate for environmental changes.

Sounds like "disturbances" to me...and compensating actions against
some kind of reference level.

Regards,

Fred Nickols
The Distance Consulting Company
nickols@worldnet.att.net
http://home.att.net/~nickols/distance.htm

"The Internet offers the best graduate-level education to be found
anywhere."

From [ Marc Abrams (980825.2154)

[From Fred Nickols (980825.1805)]

As my dictionary has it...

homeostasis: the tendency to maintain, or the maintenance
of, normal, internal stability in an organization by

coordinated >responses of the organ systems that
automatically >compensate for environmental changes.

Sounds like "disturbances" to me...and compensating
actions against some kind of reference level.

Dueling Dictionaries :slight_smile: Your dictionary's definition of
homeostasis certainly makes it "sound" like a control
system. Mine gives a different impression. :slight_smile:

Homeostasis:
Homeostasis, in biology, tendency of biological systems to
maintain a state of "equilibrium". ( scare quotes are
mine )This tendency ranges from systems of internal balance
in individual living things to ecological patterns of
balance in a community, such as the balance between numbers
of predators and prey. Examples of homeostasis include the
body's self-regulation of hormone and acid-base levels, the
composition of body fluids, cell growth, and body
temperature.

Equilibrium:
A condition in which all acting influences are canceled by
others, resulting in a stable, balanced, or unchanging
system.

Maybe the concept of homeostasis _should_ be replaced by
control. I do not believe they are interchangeable terms.
See Bruce Abbotts _leaky bucket_ 2 ,3, 4, and Bill's #5 and
6.

Marc

[From Bill Powers (980826.0319 MDT)]

Marc Abrams (980825.2154)--

[From Fred Nickols (980825.1805)]

As my dictionary has it...

homeostasis: the tendency to maintain, or the maintenance
of, normal, internal stability in an organization by

coordinated >responses of the organ systems that
automatically >compensate for environmental changes.

Note how "responses" takes the place of "actions," and "coordination" and
"automatic compensation" are invoked without the least understanding of how
they're accomplished.

Marc:

Dueling Dictionaries :slight_smile: Your dictionary's definition of
homeostasis certainly makes it "sound" like a control
system. Mine gives a different impression. :slight_smile:

Homeostasis:
Homeostasis, in biology, tendency of biological systems to
maintain a state of "equilibrium". ( scare quotes are
mine )This tendency ranges from systems of internal balance
in individual living things to ecological patterns of
balance in a community, such as the balance between numbers
of predators and prey. Examples of homeostasis include the
body's self-regulation of hormone and acid-base levels, the
composition of body fluids, cell growth, and body
temperature.

Equilibrium:
A condition in which all acting influences are canceled by
others, resulting in a stable, balanced, or unchanging
system.

A lovely mixture of equilibrium and control concepts, without any awareness
that they involve fundamentally different mechanisms.

Maybe the concept of homeostasis _should_ be replaced by
control. I do not believe they are interchangeable terms.
See Bruce Abbotts _leaky bucket_ 2 ,3, 4, and Bill's #5 and
6.

Actually, all the examples of homeostasis of which I'm aware ARE active
control processes, with the details fairly well known. Furthermore, all of
them involve _variable_, not "static", reference levels: see the book
"Homeorhesis," by Myrsovski (sp?).

Best,

Bill P.