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Slide 1

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Stimulus (change Receptor (detects
(compares actual Effector (brings about Response (restoring
from the normal or change from the
values with the the corrective action) the normal value)
set point) normal)
normal)…read more

Slide 2

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What is homeostasis?
· Homeostasis is the maintenance of constant
internal conditions, such as temperature, pH,
water potential and blood glucose
· Homeostasis ensures that the cells of a body
are in an environment that meets their needs
and allows them to function normally despite
external changes…read more

Slide 3

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Control mechanisms…read more

Slide 4

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Principles of negative feedback
· Negative feedback: Negative feedback means
that whenever a change occurs in a system,
the change automatically causes a corrective
mechanism to start, which reverses the
original change and brings the system back to
normal. It also means that the bigger then
change the bigger the corrective mechanism.…read more

Slide 5

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Negative feedback continued
Negative feedback is a natural mechanism the body employs in an attempt to keep
the body's conditions close to the body's set point. When the body senses a
change away from it's normal set point, the body engages mechanisms to help
reverse or counteract these changes.…read more

Slide 6

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Principles of positive feedback
· Positive feedback occurs when the change
stimulates a further change in the same
direction. Positive feedback is potentially
dangerous and is usually associated with a
breakdown in the normal control mechanism. It
occur when the feedback causes the corrective
measures to be turned on (like in hypothermia,
or in neurones when a stimulus causes a small
influx of sodium ions that increases the
permeability of neurone to ions so more enter)…read more

Slide 7

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