CONNECT!
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What was it like
learning to ride a
bike?
Could you ride in a
straight line and
balance, at first?
What happened if you
couldn’t?
If you viewed your
path from above on
your first successful,
independent ride,
what would it look
like?
Homeostasis
is maintaining a
stable internal
environment
even in a
changing
environment
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Responses to Environmental Change
Organism
Change
(Stimulus)
Reaction
(Response)
Plants
Hot and dry
weather
Stomates close
to conserve
water
Produce an
“antifreeze”
chemical
Heart rate
increases
Some species of Temp below a
bacteria
certain point
Human
Hears a loud
noise at night
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Homeostasis is
the maintenance
of internal
conditions within
a narrow range
that varies only
slightly over time
it is necessary to
keep every living
thing alive
Blood Sugar Example
Blood sugar levels show a rise after a meal but
the body quickly restores these levels to
equilibrium using the hormone insulin.
This example illustrates why homeostasis can be
considered dynamic equilibrium (or adjusting
balance), since the body constantly monitors and
makes adjustments to keep us alive.
Homeostasis Graph
Chunk Time!
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Define homeostasis.
Define stimulus and response.
Give examples of how plants, some bacteria, and
humans respond to changes in their environment.
Explain how the body maintains blood sugar level in a
narrow range after a meal.
Why is homeostasis also called “dynamic equilibrium”?
Describe a graph of homeostasis – show it with your
hands.
What happens if the body condition continually increases
or decreases?
Why do you think I chose a balance to be the
background for the homeostasis notes?
Connect!
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If you are the football player that catches the
quarterback’s passes, what is your position?
If you still have a house phone line, and it rings,
what do you pick up?
So…“receptor” is another word for _____.
A. Cell-to-cell Communication
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The “Ultimate Maintainer” is the cell membrane which is
for allowing materials into and out of the cell as well as
receiving messages from other cells
HOMEOSTASIS
IS MAINTAINED BY
CELL TO CELL COMMUNICATION
IS ACHIEVED BY
NERVOUS
ENDOCRINE
SYSTEM
SYSTEM
BOTH USING
RECEPTORS IN
CELL MEMBRANE
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How do the different parts of your body “know”
how to play soccer when you want them to?
How does your body “know” when to go through
a growth spurt?
It’s all about cell to cell communication and
the two systems involved – the nervous and
endocrine systems, which together coordinate
and control our bodies by receiving and sending
messages.
Chunk Time!
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What is the function of the cell
membrane?
How is homeostasis maintained?
How is cell-to-cell communication
achieved?
What does “receptor” mean?
What two systems coordinate and control
our bodies by sending and receiving
messages?
Nervous System
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Basically your body is “wired’ the same way the
electric company has wired our homes for
electricity. You have specific cells that carry
messages for you called neurons (nerve cells).
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Neurons conduct electrical signals called
impulses very quickly from one part of the
body to another. It takes a fraction of a
second for your brain to tell your body to
move out of the way of a speeding car.
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Nerve cells secrete chemicals that signal
adjacent nerve, muscle or gland cells.
These secretions are detected by specific
receptor molecules on the cell membranes
which receive the message.
The chemicals are
called
neurotransmitters.
Chunk!
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What is the proper name for a nerve cell?
What is the job of nerve cells?
What kind of signals do nerve cells carry?
What are the chemicals called that
neurons release at the end of the cell?
How does the next cell pick up the
message?
What is the gap between one neuron and
the next called?
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What happens if homeostasis is not
maintained in an organism?