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Bio 220 Lecture 11:
Coordination of complex organisms
Campbell,
5th, pp. 778-790, 993-996, 188-190, 893-896
I.
Communication between organ systems
A
complex, multicellular organism requires communication
between different cells and tissues.
It
is necessary for:
- coordination of different
organ systems
- ability to respond to
altered situations
- maintenance of
homeostasis
A.
Homeostasis40.11
Homeostasisis
the steady-state physiological condition of the body
of an animal. The internal
environment is
notconstant; it is a
dynamic
equilibriumwhere
changes occur, but they are countered in such a
way as to keep them within the
acceptable range.
This requires three components:
1.
Receptor-
detects change in environment
2. Control
center- processes
information 3.
Effector-
responds to change
Humans
use these mechanisms to regulate temperature (37ºC),
blood glucose (800 mg/ml), O2 (100 mm Hg), CO2 ( 40mm Hg),
Na+ (142 mEg/L) and K+ (4 mEq/L).
D.
Negative vs Positive
feedback40.12
Negative
feedback: a change in
a variable triggers a response that
counteractsthat
change. For example, a thermostat senses that the
temperature has fallen below the set point and activates the
furnace to heat the room.
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