Transcript Homeostasis Notes

Homeostasis
Negative feedback systems in the
human body
What is homeostasis?
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Process that occurs in all
living things
All organ systems work
together to achieve
homeostasis
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http://en.wikipedia.org/wiki/File:Tightrope_artist_Cologne_1.jpg
Ability of an organism
to maintain its internal
balance, despite
changes to its internal
or external
environment
http://www.flickclip.com/flicks/osmosisjones1.html
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How does homeostasis work?
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http://en.wikipedia.org/wiki/File:Southern_12_stage-02_1988.jpg
Feedback pathways
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A cellular relay race!
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Specific organs and
structures must
communicate with each
other in response to
changes in the body
Keeps levels of certain
processes within a
normal range
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What things in your body need to be
kept within a range?
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Body Temperature
Blood pressure
Blood pH
O2 and CO2 concentration
Osmoregulation-Water balance
Blood glucose
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Involves a stimulus and a
response
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Stimulus - something that causes a
physiological or psychological response.
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Response -any behavior of a living
organism that results from an external or
internal stimulus
Cellular Relay Race
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Stimulus
Receptor
Integrating
center
Effector
Response
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Reverses the
stimulus
Negative Feedback Pathways
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Way in which most
homeostatic
mechanisms work
The product of the
pathway inhibits, or
shuts down, the
original signal
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Why is this an
important feature in
living things?
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Why is feedback important in
living things?
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Allows baseline to be
regained
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Conserves resources
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Cellular Materials
Energy (ATP)
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mouth
Stomach
Sm. Intestine
Circulatory Runners
Target cellsBrain
Target cellsMuscle
Target cellsLiver
Pancreas
ß-cells
Game set-up
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http://en.wikipedia.org/wiki/File:Archery_Target_80cm.svg
http://en.wikipedia.org/wiki/File:Llave_bronce.jpg
http://commons.wikimedia.org/wiki/File:Day-template.svg
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mouth
Stomach
Sm. Intestine
Circulatory Runners
Target cellsBrain
Target cellsMuscle
Target cellsLiver
“Glucose!! Release the insulin!”
Pancreas
ß-cells
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Lots of glucose
circulating, so
Pancreas calls out
for insulin
http://commons.wikimedia.org/wiki/File:Pictgram_running_man.svg
http://en.wikipedia.org/wiki/File:Archery_Target_80cm.svg
http://en.wikipedia.org/wiki/File:Llave_bronce.jpg
http://commons.wikimedia.org/wiki/File:Day-template.svg
http://commons.wikimedia.org/wiki/File:Icon_announcer.svg
mouth
Stomach
Sm. Intestine
Circulatory Runners
Target cellsBrain
Target cellsMuscle
Target cellsLiver
“Glucose!! Release the insulin!”
Pancreas
ß-cells
Life Sciences-HHMI Outreach. Copyright 2009 President and Fellows of Harvard College.
Insulin has been
passed to the target
cells. Targets can
now receive
glucose.
http://commons.wikimedia.org/wiki/File:Pictgram_running_man.svg
http://en.wikipedia.org/wiki/File:Archery_Target_80cm.svg
http://en.wikipedia.org/wiki/File:Llave_bronce.jpg
http://commons.wikimedia.org/wiki/File:Day-template.svg
http://commons.wikimedia.org/wiki/File:Icon_announcer.svg
mouth
Stomach
Sm. Intestine
Circulatory Runners
Target cellsBrain
Target cellsMuscle
Target cellsLiver
“Hold insulin production”
Pancreas
ß-cells
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Pancreas stops
insulin from being
passed once
there is no more
glucose
circulating
http://commons.wikimedia.org/wiki/File:Pictgram_running_man.svg
http://en.wikipedia.org/wiki/File:Archery_Target_80cm.svg
http://en.wikipedia.org/wiki/File:Llave_bronce.jpg
http://commons.wikimedia.org/wiki/File:Day-template.svg
http://commons.wikimedia.org/wiki/File:Icon_announcer.svg
Dueling Hormones
What goes up, must come down!
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Insulin
Produced by -cells
of the Pancreas
Released into
circulatory system
when blood glucose is
high
Facilitates the
transport of glucose
into target cells
Glucagon
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Produced by -cells
of the pancreas
Released into the
circulatory system
when blood glucose is
low
Signals the liver to
break down glycogen
into simple glucose
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Dueling Mechanisms
What goes up, must come down!
Thermoregulation
Sweating (cooling) vs. shivering (warming)
Blood Pressure
Vasconstriction vs. vasodilation
Osmoregulation
Hypotonic vs. hypertonic
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Food for thought…
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On average, how many organ systems are
involved in each of the processes we’ve
explored?
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Are there any organ systems that you see in
all of these processes?
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What might happen to these pathways if just
one system was not functioning properly?
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