The Need to Maintain Homeostasis!
Each cell is a sophisticated
machine, finely tuned to carry out
a precise role within the body!
When does this
specialization occur, you
ask? Only within narrow limits of
temperature, pH, concentrations
of glucose and oxygen and many
other factors that must be held
relatively constant for cells to
function properly.
Homeostasis, then, can be
defined as the dynamic constancy
of the internal environment.
An elephant regulating body
temperature by spraying water on
ortant for life! himself.
Lesson 1: Kidney Structure and Function
Lesson 2: Introduction to Homeostasis
Introduce the concept of homeostasis
Lesson 3-4: Excretory System
Describe the other components of the
excretory system and how they all interact.
Lesson 5: Kidney Dissection Lab
Discover the anatomy of the kidney through
dissection.
Lesson Sequence
Introduce anatomy and physiology of the
kidney and excretory system.
Discuss the concept of a feedback system and a
response loop.
Lesson 7: Control Mechanisms
Discuss the different control mechanisms that
the body uses to regulate water in the body.
Lesson 8: Effects on Excretory System
Investigate how different substances and/or
environment affect the excretory system when
subject to various chemicals and/or stimuli.
Lesson 9-10: Culminating Task
Lab investigation observing the responses that
an invertebrate may have to different stimuli.
Lesson Sequence continued
Lesson 6: Feedback System (Stimulus
response loop)
E1.1 assess, on the basis of findings from a case
Curriculum
Expectations
study, the effects on the human body of taking
chemical substances to enhance performance or
improve
E1.2 evaluate, on the basis of research, some of the
human health issues that arise from the impact of
human activities on the environment
E2.1 use appropriate terminology related to
homeostasis, including, but not limited to: insulin,
testosterone, estrogen, nephron, dialysis, pituitary,
synapse, and acetylcholine
E2.2 plan and construct a model to illustrate the
essential components of the homeostatic process
E2.3 plan and conduct an investigation to study a
feedback system
E2.4 plan and conduct an investigation to study the
response mechanism of an invertebrate to external
stimuli
E3.1 describe the anatomy and physiology of the
endocrine, excretory, and nervous systems, and
explain how these systems interact to maintain
homeostasis
E3.3 describe the homeostatic processes involved
in maintaining water, ionic, thermal, and acid–base
equilibrium, and explain how these processes help
body systems respond to both a change in
environment and the effects of medical treatments
The Mammalian
Kidney
In humans, the kidneys are fist-sized
organs located in the region of the lower
back. Each kidney receives blood from a
renal artery, and it is from this blood that
urine is produced. Urine drains from
each kidney through a ureter, which
carries the urine to a urinary bladder.
Within the kidney, the mouth of the
ureter flares open to form a funnel-like
structure, the renal pelvis. The renal
pelvis, in turn, has cup-shaped
extensions that receive urine from the
renal tissue. This tissue is divided into an
outer renal cortex and inner renal
medulla. Together, these structures
perform filtration, reabsorption,
secretion, and excretion.
Nephrons
The nephron tubule is surrounded by peritubular capillaries, which
carry away molecules and ions that are reabsorbed from the filtrate.
Functions of the Kidneys
The kidneys have four main functions. Molecules enter the urine by filtration out of
the glomerulus and by secretion into the tubules from surrounding peritubular
capillaries. Molecules that entered the filtrate can be returned to the blood by
reabsorption from the tubules into surrounding peritubular capillaries, or they
may be eliminated from the body by excretion through the tubule to a ureter, then
to the bladder.
Teaching Approaches
Lesson Strategy
Students will create a hand-made
wordle for homeostasis (this will
give me an idea of what they
already know).
Lecture using either the video or
textbook to go through structure
and function of kidney
Mini-challenge: Create a story
starting with I am a kidney named …
(should include some structures
and functions talked about in class).
Assessment
Diagnostic Assessment of
the wordle, what they may
already know.
Mini-challenge, a diagnostic
assessment to see what
they have learned.
Homeostasis
Homeostasis Lesson
Homeostasis Gizmo
Provides an overview on
homeostasis and body balance
using videos, examples, and
charts etc.
Adjust the levels of
clothing, perspiration, and
exercise to maintain a
stable internal temperature
as the external temperature
changes.
http://www.lionden.com/homeost
asis.htm
Also Easy Study Canada has
made a study guide for students
to review homeostasis.
http://easystudy.ca/?p=2132
http://www.explorelearning.
com/index.cfm?method=cR
esource.dspDetail&Resourc
eID=519
Teaching Approaches
Lesson Strategy
Intro to homeostasis (the
basics using lecture or
slides etc.)
Gizmo: Human
Homeostasis, fill out
worksheet that goes with it.
Mini challenge: definition of
homeostasis in your own
words
Assessment
Quiz: kidney
structure/function
Gizmo worksheet completion,
diagnostic to see if they
understood the gizmo
Mini-challenge: to see if they
understand the concept to
make their own definition
(diagnostic)
Excretory System
Overview Slideshow
This slideshow goes
through everything from
excretion and homeostasis
to the functions of the
kidneys etc.
http://www.slideshare.net/Si
anfergs/the-humanexcretory-system-10220059
YouTube Video
This is a cool commoncraft
youtube video explaining
the excretory system in
detail, students can make
one of their own as an
assignment.
http://www.youtube.com/wa
tch?v=47OKHDqu2Hc
Teaching Approaches
Lesson Strategy
This was divided into two lessons
so the first one we would start out
with a mini challenge: who can
remember the most components
of the excretory system.
Lecture/slideshow presentation
with the information.
Take home assignment: create a
study guide for the lecture/info
from todays lesson
Assessment
Quiz: Homeostasis
Study guide assignment,
diagnostic to see where
they are with the material
Teaching Approaches continued
Lesson Strategy
The lesson after will start with the
study guide check.
Mini challenge: name the steps
for removing waste from the body
Get into groups to create a
commoncraft presentation, which
they will be given an example
from the youtube video mentioned
on slide 14.
They have until the end of class.
Present next class.
Assessment
Study guide check,
diagnostic
Commoncraft presentation
with rubric
Mini challenge, diagnostic
Safety Considerations for the Lab
Your lab tools should be cleaned, dried and returned at the
end of the class.
Your group is solely responsible for your scalpel. Show
your equipment to the teacher before returning it.
Always wash your hands with soap and your work area
when you are finished.
Handle dissecting tools carefully (don’t cut directly
towards yourself or your lab partner(s)).
You should wear gloves and safety goggles. Lab aprons
are available if you choose to use them.
Teaching Approaches
Lesson Strategy
They will be given the
kidney dissection package
to complete the lab during
this class, the package is
located on slide 17.
Mini-challenge: name one
part of the kidney you
labeled today and it’s
function
Assessment
Lab report due next lesson
(basically hand in package),
assessment criteria is at the
end of the package.
Mini challenge, diagnostic
Negative
Feedback Loops
Negative feedback loops
maintain a state of homeostasis,
or dynamic constancy of the
internal environment, by
correcting deviations from a set
point.
Perturbing factor
Stimulus:
Deviation from set
point
Integrating centre:
Compares
conditions to set
point
Sensor:
Constantly
monitors
conditions
Effector: Causes
changes to
compensate for
deviation
Response: Return
to set point
Negative
Feedback loops
continued
Negative feedback loops keep the
body temperature within a normal
range. An increase or decrease in
body temperature is sensed by the
brain. The integrating centre in the
brain then processes the
information and activates
effectors, such as surface blood
vessels, sweat glands, and skeletal
muscles. When the body
temperature returns to normal,
negative feedback prevents further
stimulation of the effectors by the
integrating centre.
Positive
Feedback Loops
An example of positive feedback
during childbirth. This is one of
the few examples of positive
feedback that operate in the
vertebrate body.
Feedback System
Tutorial plus Animation
YouTube Video
This tutorial is pretty nifty, it
shows an animation along
with the explanations of
control, regulation and
feedback in homeostasis.
This video gives a super
thorough explanation of
negative versus positive
feedback with real life
examples. Courtesy of Mr.
Anderson.
http://bcs.whfreeman.com/t
helifewire/content/chp41/41
020.html
http://www.youtube.com/watc
h?v=CLv3SkF_Eag&feature=r
elated
Teaching Approaches
Lesson Strategy
Start the class with this Seinfeld clip
and get the students to explain where
homeostasis comes in.
http://www.youtube.com/watch?v=lt6K
RKHpKhY
After this have a short lecture with the
above diagrams can include and
animation if you like and then ask the
students to create their own flow-chart
for a negative feedback loop
Mini-challenge: give me an example not
to do with bio that uses negative
feedback
Assessment
Quiz: Excretory system
Seinfeld clip discussion
participation
Mini-challenge, application
of information learned
Control Mechanisms
Antidiuretic hormone stimulates the reabsorption of water by the kidneys. This
action completes a negative feedback loop and helps to maintain homeostasis of
blood volume and osmolality.
A great animation for this particular example can also be found at the following
link: https://sites.google.com/site/virtuallabsrenal/anatomy/adh-secretion
Control Mechanisms
A lowering of blood volume activates the renin-angiotensin-aldosterone
system.
A great handwritten tutorial can be found at the following link:
http://www.youtube.com/watch?feature=fvwrel&NR=1&v=PDE2qdS2ZvY
Teaching Approaches
Lesson Strategy
Assessment
Mini-challenge: name the four main
functions of the kidney.
Quiz: feedback system
From there we will work through
control mechanisms, the use of the
animation on slide 24 and 25, along
with the textbook.
Mini-challenge, diagnostic
The students must create a
summary chart of control
mechanisms, where they occur, the
function, the substances that are
transported are some examples for
title headings. (can be done in
groups, to then do a jigsaw)
Summary flow-chart for
jigsaw, completion and
understanding (experts on
the material)
Effects on Excretory System
Certain drugs can have an effect on the excretory system
for example alcohol, illegal drugs, steroids, and even
something as simple as caffeine.
We will go over common effects of diuretics, their purpose
being to remove excess water from the body although
each type of diuretic does this in a different way.
Most common side-effects include: dehydration,
hypotension, muscle cramps, electrolyte disturbances,
muscle weakness, seizures, gout, fatigue.
Teaching Approaches
Lesson Strategy
Assessment
Start out with a what you know activity,
there will be headers on the board (alcohol,
prescription drugs, steroids and caffeine),
the students will be given sheets of paper
with how they may harm r help, they need to
stick the sheet under the appropriate
heading.
Quiz: control mechanisms
Then we will get into a discussion and look
at the drug dosage gizmo at this link:
http://www.explorelearning.com/index.cfm?
method=cResource.dspView&ResourceID=
525 , along with a worksheet
Gizmo worksheet
completion
Mini-challenge: name something you
learned today about one of the four
categories on the board
Diagnostic assessment the
on board activity
Mini-challenge, diagnostic
Differentiated Assessment: Culminating Task
Students can choose two of the following options for their culminating task
assessment on homeostasis:
A poster displaying the kidney structure (Visual)
A song about the concept of a feedback loop (Musical)
A 3-D model showing the kidney structure (Kinesthetic)
A videotaped oral or hand-written story about the process of kidney
homeostasis (Linguistic)
A journal entry on what they learned about homeostasis (Intrapersonal)
A lesson on protein synthesis that is taught to the class (Interpersonal)
A lab activity involving the response of an invertebrate to external stimuli
(Logical)
Differentiated Assessment continued
Students can choose two of the following options for their culminating task
assessment on homeostasis:
A homeostasis case study to analyze (Logical)
A patient description of health will be given, the student must determine
the patients illness as well as giving solutions to help the problem (either
present orally or in a report) (Logical/Linguistic)
A Bill-Nye episode on homeostasis (can be a play or videotaped)
(Linguistic/Kinesthetic)
A debate on some of the bad stimuli on homeostasis (example drugs,
alcohol, etc.) Must choose a group of four and each person will be given a
different perspective to present their arguments from (Interpersonal)
Concept map of homeostasis (Visual)
Safety Considerations for the Lab
For the invertebrate lab some things to consider are
ethical standards when dealing with live substances.
The invertebrate is a living being, therefore after the
lab make sure to either put it back in the wild or in a
safe place where it can still survive.
If any students are allergic to certain invertebrates
please either avoid being involved in the lab or have
a partner who is not.
Make sure to wear gloves and goggles and any other
precautions necessary for the lab.
Differentiated Assessment continued
Students understanding of kidney homeostasis will
also be evaluated through the final unit test
As well, students will be evaluated throughout the
unit by formative assessments including quizzes, the
lab assignment and the commoncraft presentation of
the excretory system.
Through diagnostic assessments of their progress,
the mini-challenges and homework completion.
Also, observations of participation and the learning
skills throughout the unit.
Potential Student Difficulties
1. Homeostasis means
stable
Sometimes the students may
mistake stable as everything
being in equilibrium in the
body which isn’t true.
Stable could also mean for
the student that nothing is
fluctuating or changing in
either the external
environment (ex.
temperature) or internal
environment (ex. body)
2. Homeostasis is the
same for everyone
Technically the term
homeostasis could be
confusing it suggests that the
body needs to maintain a
“steady-state” internal
environment.
This might be considered as
the same temperature levels,
pH and/or blood sugar levels
for everyone, but that’s also
not true.
Potential Student Difficulties
3. Assuming the kidney
collects urine
This can be confusing
because the kidney filters
the blood and eliminates a
variety of potentially
harmful substances but it
also relieves the body of
excess substances that
otherwise do not need to be
reabsorbed.
4. The Excretory System
allows everything to pass
through
The excretory system is not
an open system that allows
all substances to pass
through, there are many
different control
mechanisms that allow for
the passage of certain
substances for example
water or ions.
Possible Solutions to Student Difficulties
1. Homeostasis means
stable
The body is actually always
reacting to its external
environment (which is also
constantly changing), in
order to adapt and create
stable conditions internally.
The human body is always
monitoring what’s happening
and actively making changes
to maintain live-able
conditions.
2. Homeostasis is the
same for everyone
Everyone is an individual therefore our bodies
regulate our internal environments in different
ways.
Not everyone has the same blood pressure as we
know you can have low or high blood pressure. As
well children usually have lower blood pressure
than adults therefore their regulation differs from
other individuals.
For the most part the internal body temperature
should be at approximately 37°C but that varies
among individuals.
Body temperature can also vary according to the
external conditions like how hot or cold it is
outdoors.
Possible Solutions to Student Difficulties
3. Assuming the kidney
collects urine
The best way to explain this
would be through
animations and diagrams
showing what exactly
comes out of the blood and
or what the kidney’s
functions are. There is a
good diagram in this
presentation which can be
accompanied with an
explanation on slide 10.
4. The Excretory System
allows everything to pass
through
I love the animation for ADH
because it’s a perfect
illustration of how
reabsorption of water occurs.
(slide 23) Also perhaps
creating a class chart or
concept map of which ions or
substances get transported
through certain membranes,
for example the collecting
duct transports water, salt
(NaCl), urea, uric acid and
minerals.
Diabetes Mellitus and Diabetes Insipidus
Chronic renal diseases
Performance-enhancing drugs (steroids) and their
affect on homeostasis
Energy drinks, coffee, coke etc. and their affect on
homeostasis
Alcohol and illegal drugs and their affect on
homeostasis
Effects of medically prescribed drugs on
homeostasis (ex. diuretics)
Kidney Dialysis and transplants
Practical Applications
Dry fit t-shirts that help keep you cool or parkas to
keep you warm (clothing to regulate body
temperature)
Gerards, Susan (2011). Biology 12. Toronto: McGraw-Hill
Ryerson.
Provides background information and
diagrams for lessons.
Provides more background information of the kidney for
students to review.
Control, Regulation and Feedback Tutorial
http://bcs.whfreeman.com/thelifewire/content/chp41/41020.
html Gives overview of feedback mechanisms and how the
body controls itself.
Homeostasis Lesson
http://www.lionden.com/homeostasis.htm Overview of
homeostasis.
Kidney Quiz
http://www.zerobio.com/target_practice_quiz/target_pr
actice_quiz_kidney.htm Allows students to self-quiz
themselves on their knowledge of the kidney.
Resources
Kidney Tutorial
http://www.biologymad.com/resources/kidney.swf
understand how the human body regulates its water, temperature
and activity levels.
Gizmo: Drug Dosage
http://www.explorelearning.com/index.cfm?method=cResource.dsp
View&ResourceID=525 Interactive simulation for students to
investigate how drug dosage affects the body.
Khan Academy: Kidney and Nephron Overview
http://www.khanacademy.org/science/biology/v/the-kidney-andnephron?playlist=Biology An interactive video providing an
overview of both the kidneys and the nephrons.
Easy Study Canada http://easystudy.ca/?p=2132 This is an exam
review guide of grade 12: homeostasis.
The Human Excretory System on Slideshare
http://www.slideshare.net/Sianfergs/the-human-excretory-system10220059 This slideshow goes through everything from excretion
and homeostasis to the functions of the kidneys etc.
Resources continued
Gizmo: Human Homeostasis
http://www.explorelearning.com/index.cfm?method=cResource.dsp
Detail&ResourceID=519 Interactive simulation for students to
explaining or giving an overview of the excretory system.
Kidney Dissection Mini-Lab
http://www.imarksweb.net/book/kidney+dissection+answers/ This is a pdf
document that is located on my computer or it can be found at the site above.
YouTube – Positive and Negative Feedback Loops
http://www.youtube.com/watch?v=CLv3SkF_Eag&feature=related This video
gives a super thorough explanation of negative versus positive feedback with
real life examples, courtesy of Mr. Anderson.
YouTube – Seinfeld: George’s Gore-Tex Coat
http://www.youtube.com/watch?v=lt6KRKHpKhY This video was meant just as
a minds-on activity, to get the students to think outside of the box and consider
why this could be an example of homeostasis.
Virtual Labs Renal https://sites.google.com/site/virtuallabsrenal/anatomy/adhsecretion This is a great simulation of ADH and how it functions within the
body.
YouTube – Renin-Angiotensin-Aldosterone System
http://www.youtube.com/watch?feature=fvwrel&NR=1&v=PDE2qdS2ZvY This
is a hand-written tutorial, therefore it has drawings as well as an oral
presentation on video explaining this hormone complex.
Resources continued
YouTube - Commoncraft: The Excretory System
http://www.youtube.com/watch?v=47OKHDqu2Hc This video is a cool way of