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Positive
feedback: a change in a variable triggers a response
that
augmentsthe change.
For example, during childbirth, when contractions are
detected by stretch receptors, they signal the hypothalamus
to release a hormone (oxytocin) that stimulates more
contractions. Rather than reestablishing equilibrium,
positive feedback leads to a definite conclusion.
Both
types of feedback loops need all 3 components,
for
aroom heater:
Thermostat
(sensor)Æcontrol
panelÆheater
(effector)
There
are a set of questions that you should ask about any type of
communication/information transfer involved in coordinating
an organism.
For
the heater:
Q. What kindof
information is being sent?
- thermostat is sending "I'm
cold", control panel is sending "turn on" comand
Q.
Howis information
being sent?
- information generally sent
by electricity through a wire
Q.
What does this imply about the
speedof the process?
- fast
Q.
How responsiveis it to
change detected by sensor? -
very responsive, essentially as soon as the thermostat
detects the change, the heater turns off or on
Q.
How is the level of responsiveness appropriate to the
situation? - this is good because if there is a lag turning
off, it would cause the heater to overshoot, wasting
energy
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