Homeostasis - Life Sciences Outreach Program
Homeostasis - Life Sciences Outreach Program
Homeostasis - Life Sciences Outreach Program
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<strong>Homeostasis</strong><br />
Negative feedback systems in the<br />
human body<br />
By Karyn Coulon<br />
Masconomet Regional High School<br />
<strong>Life</strong> <strong>Sciences</strong>-HHMI <strong>Outreach</strong>.<br />
Copyright 2009 President and Fellows<br />
of Harvard College.
What is homeostasis?<br />
<br />
<br />
Process that occurs in all<br />
living things<br />
All organ systems work<br />
together to achieve<br />
homeostasis<br />
<br />
Ability of an organism to<br />
maintain its internal<br />
environment, despite<br />
changes to its internal or<br />
external environment<br />
http://en.wikipedia.org/wiki/File:Tightrope_artist_Cologne_1.jpg<br />
<strong>Life</strong> <strong>Sciences</strong>-HHMI <strong>Outreach</strong>.<br />
Copyright 2009 President and Fellows<br />
of Harvard College.
How does homeostasis work?<br />
<br />
Feedback pathways<br />
<br />
A cellular relay race!<br />
<br />
Specific organs and<br />
structures must<br />
communicate with each<br />
other in response to<br />
changes in the body<br />
http://en.wikipedia.org/wiki/File:Southern_12_stage-02_1988.jpg<br />
<br />
Keeps levels of certain<br />
processes within a<br />
normal range<br />
<strong>Life</strong> <strong>Sciences</strong>-HHMI <strong>Outreach</strong>.<br />
Copyright 2009 President and Fellows<br />
of Harvard College.
What things in your body need to be<br />
Body Temperature<br />
Blood pressure<br />
Blood pH<br />
kept within a range?<br />
O 2 and CO 2 concentration<br />
Osmoregulation-Water balance<br />
Blood glucose<br />
<strong>Life</strong> <strong>Sciences</strong>-HHMI <strong>Outreach</strong>.<br />
Copyright 2009 President and Fellows<br />
of Harvard College.
Cellular Relay Race<br />
Stimulus<br />
Receptor<br />
Integrating<br />
center<br />
Effector<br />
Response<br />
Reverses the<br />
stimulus<br />
<strong>Life</strong> <strong>Sciences</strong>-HHMI <strong>Outreach</strong>.<br />
Copyright 2009 President and Fellows<br />
of Harvard College.
Negative Feedback Pathways<br />
<strong>Life</strong> <strong>Sciences</strong>-HHMI <strong>Outreach</strong>.<br />
Copyright 2009 President and Fellows<br />
of Harvard College.<br />
Way in which most<br />
homeostatic<br />
mechanisms work<br />
The product of the<br />
pathway inhibits, or<br />
shuts down, the<br />
original signal<br />
Why is this an<br />
important feature in<br />
living things?
Why is feedback important in<br />
living things?<br />
Allows baseline to be<br />
regained<br />
Conserves resources<br />
Cellular Materials<br />
Energy (ATP)<br />
<strong>Life</strong> <strong>Sciences</strong>-HHMI <strong>Outreach</strong>.<br />
Copyright 2009 President and Fellows<br />
of Harvard College.
mouth<br />
Stomach<br />
Sm. Intestine<br />
Circulatory Runners<br />
Target cells-<br />
Muscle<br />
Target cells-<br />
Brain<br />
Target cells-<br />
Liver<br />
Pancreas<br />
ß-cells<br />
Game set-up<br />
<strong>Life</strong> <strong>Sciences</strong>-HHMI <strong>Outreach</strong>. Copyright 2009 President and Fellows of Harvard College.<br />
http://commons.wikimedia.org/wiki/File:Pictgram_running_man.svg<br />
http://en.wikipedia.org/wiki/File:Archery_Target_80cm.svg<br />
http://en.wikipedia.org/wiki/File:Llave_bronce.jpg<br />
http://commons.wikimedia.org/wiki/File:Day-template.svg<br />
http://commons.wikimedia.org/wiki/File:Icon_announcer.svg
mouth<br />
Stomach<br />
Sm. Intestine<br />
Circulatory Runners<br />
Target cells-<br />
Muscle<br />
Target cells-<br />
Brain<br />
Target cells-<br />
Liver<br />
“Glucose!! Release the insulin!”<br />
Pancreas<br />
ß-cells<br />
<strong>Life</strong> <strong>Sciences</strong>-HHMI <strong>Outreach</strong>. Copyright 2009 President and Fellows of Harvard College.<br />
Lots of glucose<br />
circulating, so<br />
Pancreas calls out<br />
for insulin<br />
http://commons.wikimedia.org/wiki/File:Pictgram_running_man.svg<br />
http://en.wikipedia.org/wiki/File:Archery_Target_80cm.svg<br />
http://en.wikipedia.org/wiki/File:Llave_bronce.jpg<br />
http://commons.wikimedia.org/wiki/File:Day-template.svg<br />
http://commons.wikimedia.org/wiki/File:Icon_announcer.svg
mouth<br />
Stomach<br />
Sm. Intestine<br />
Circulatory Runners<br />
Target cells-<br />
Muscle<br />
Target cells-<br />
Brain<br />
Target cells-<br />
Liver<br />
“Glucose!! Release the insulin!”<br />
Pancreas<br />
ß-cells<br />
<strong>Life</strong> <strong>Sciences</strong>-HHMI <strong>Outreach</strong>. Copyright 2009 President and Fellows of Harvard College.<br />
Insulin has been<br />
passed to the target<br />
cells. Targets can<br />
now receive<br />
glucose.<br />
http://commons.wikimedia.org/wiki/File:Pictgram_running_man.svg<br />
http://en.wikipedia.org/wiki/File:Archery_Target_80cm.svg<br />
http://en.wikipedia.org/wiki/File:Llave_bronce.jpg<br />
http://commons.wikimedia.org/wiki/File:Day-template.svg<br />
http://commons.wikimedia.org/wiki/File:Icon_announcer.svg
mouth<br />
Stomach<br />
Sm. Intestine<br />
Circulatory Runners<br />
Target cells-<br />
Muscle<br />
Target cells-<br />
Brain<br />
Target cells-<br />
Liver<br />
“Hold insulin production”<br />
ß-cells<br />
Pancreas<br />
Pancreas stops<br />
insulin from being<br />
passed once<br />
there is no more<br />
glucose<br />
circulating<br />
<strong>Life</strong> <strong>Sciences</strong>-HHMI <strong>Outreach</strong>. Copyright 2009 President and Fellows of Harvard College.<br />
http://commons.wikimedia.org/wiki/File:Pictgram_running_man.svg<br />
http://en.wikipedia.org/wiki/File:Archery_Target_80cm.svg<br />
http://en.wikipedia.org/wiki/File:Llave_bronce.jpg<br />
http://commons.wikimedia.org/wiki/File:Day-template.svg<br />
http://commons.wikimedia.org/wiki/File:Icon_announcer.svg
Dueling Hormones<br />
What goes up, must come down!<br />
Insulin<br />
Produced by β-cells<br />
of the Pancreas<br />
Released into<br />
circulatory system<br />
when blood glucose is<br />
high<br />
Facilitates the<br />
transport of glucose<br />
into target cells<br />
<strong>Life</strong> <strong>Sciences</strong>-HHMI <strong>Outreach</strong>.<br />
Copyright 2009 President and Fellows<br />
of Harvard College.<br />
Glucagon<br />
Produced by α-cells<br />
of the pancreas<br />
Released into the<br />
circulatory system<br />
when blood glucose is<br />
low<br />
Signals the liver to<br />
break down glycogen<br />
into simple glucose
Dueling Mechanisms<br />
What goes up, must come down!<br />
Thermoregulation<br />
Sweating (cooling) vs. shivering (warming)<br />
Blood Pressure<br />
Vasconstriction vs. vasodilation<br />
Osmoregulation<br />
Hypotonic vs. hypertonic<br />
<strong>Life</strong> <strong>Sciences</strong>-HHMI <strong>Outreach</strong>.<br />
Copyright 2009 President and Fellows<br />
of Harvard College.
Food for thought…<br />
On average, how many organ systems are<br />
involved in each of the processes we’ve<br />
explored?<br />
Are there any organ systems that you see in<br />
all of these processes?<br />
What might happen to these pathways if just<br />
one system was not functioning properly?<br />
<strong>Life</strong> <strong>Sciences</strong>-HHMI <strong>Outreach</strong>.<br />
Copyright 2009 President and Fellows<br />
of Harvard College.
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