Jennifer McFarlane
Lorraine Garofalo
Curriculum Expectations
 E3.1 describe the anatomy and physiology of the endocrine, excretory,
and nervous systems, and explain how these systems interact to
maintain homeostasis
 E3.2 explain how reproductive hormones act in human feedback
mechanisms to maintain homeostasis (e.g., the actions of male and
female reproductive hormones on their respective body systems)
 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 (e.g., the role of feedback
mechanisms in water balance or thermoregulation; how the buffering
Lesson Sequence
Lesson 1: Homeostatic Mechanisms
 Introduction to Homeostasis: Kidney, Immune System, Nervous
System
Lesson 2: Feedback Systems
 Human Body Temperature, Transfer of Energy, Negative Feedback
Loop, Positive Feedback Loop
Lesson 3: The Human Urinary System
 Overview of the Human Urinary System, Anatomy, Comparison of
Male & Female Systems
Lesson 4: Kidney Function and Structure
 General Structure of the kidney and nephron
Lesson 5: How Blood is Filtered in the Kidney
 Role of Kidney in Maintaining Homeostasis
Lesson 6: Urine Output and Water Homeostasis
Background Information
How does the body maintain a
stable state?
 The body has developed physiological and biochemical
mechanisms that allow it to maintain its internal environment in
a relatively stable state. The body is able to do so in the face of
external stresses such as high or low temperatures and internal
stresses such as fever and infection.
 Homeostasis is a state of balance inside the body, where the
body systems work together to keep it functioning normally. The
endocrine system keeps this internal balancing act going by
releasing chemicals called hormones. This release of hormones
is controlled by negative feedback mechanisms.
Video & Virtual Lab:
Introduction to Homeostasis
VIDEO:
 Explains homeostasis for students learning the topic for the first
time
http://www.learnerstv.com/animation/animation.php?ani=241&cat=Biology
GIZMO:
 As external temperature and internal water and blood sugar
levels change, adjust factors to maintain internal stability.
http://www.explorelearning.com/index.cfm?method=cResource.dspDetail&R
esourceID=519
Negative Feedback Loop
 A process that detects and reverses deviations from
normal body constants.
 3 parts: a receptor, an integrator, and an effector.
 start at normal range  go beyond normal range  return to normal
Sensory Receptors:
 found throughout every body organ and tissue.
 Function is to send nerve impulses (stimuli) to the brain in response to
environmental information
 monitor the body’s internal conditions, such as temperature, blood pH,
blood sugar, and blood pressure, on a continual basis.
Negative Feedback Loop Animation
 is an interactive online activity which can be used as a demonstration
by the teacher using a projector, or can be an interactive activity for the
students if a computer lab is booked.
http://www.khanacademy.org/video/the-kidney-andnephron?playlist=Biology
Positive Feedback Loop
 less common in types of homeostasis
 positive feedback systems reinforce any changes --
they move the controlled variable even further away
from a steady state, causing a discrete physiological
event to be accomplished rapidly.
Bodily Constants
 Blood glucose concentration = ~ 100 mg/mL
 Blood pressure = ~ 160/106 KPa (120/80 mm Hg)
 Body temperature = ~ 37ºC
 Blood pH = ~ 7
Structure & Function of the Kidney
VIDEO:
 An excellent review on the
Functions and Structure of
the Kidney and the Nephron:
http://www.khanacademy.org/video/
the-kidney-andnephron?playlist=Biology
Kidney Homeostasis
Think-Pair-Share Opening Activity
 Using the next slide, have students brainstorm on
their own, then in pairs, how they think the body
responds to the following internal/external stresses.
 Students to then share their ideas with the class
(teacher facilitates).
thirst
food poisoning
How does
the body
respond to
internal
and
external
stresses?
high blood pressure
abnormal blood composition
Diagnostic Assessment
 Have students fill out a KWL chart in pairs guide
instruction and clear up any misconceptions about
kidney homeostasis.
What role do
the kidneys
play in
homeostasis?
The Kidney and Homeostasis
 The kidney maintains homeostasis by regulating the
following mechanisms:
1.
2.
3.
4.
5.
Water Balance
Blood Pressure
Blood Composition
Blood pH
Waste Removal
Water Balance Inquiry Activity
The Physiological Effects of Coffee
Physiological Effects of Coffee
 students to design an experiment that allows them to
measure the physiological effect of coffee
 Students to prepare a laboratory report
If it is decided that coffee will not be consumed:
 Students can research findings on the internet
OR
 Students can interview family/friends who drink coffee
(Activity taken from McGraw-Hill Ryerson, 2002, Biology 12, pp. 118-119)
1. Water Balance
 Hypothalamus directs the pituitary gland
of the endocrine system to control levels
of the hormone vasopressin or antidiuretic
hormone (ADH) in the blood
 This hormone travels through the blood to
the kidneys where it directs the rate of
water reabsorption
 Increased vasopressin ➔ increased water
reabsorption
 Decreased vasopressin ➔ decreased water
reabsorption
Fluid Balance Game
PURPOSE:
 To help students gain a better understanding of fluid balance in the
nephron
 To provide students with a fun and kinesthetic learning opportunity
PREPARATION:
 clear the classroom of desks or use an alternative open space
 25 sheets of white paper crumbled into balls – represent sodium
 25 sheets of blue paper crumpled into balls – represents water
GOAL OF GAME:
 to keep an equal balance of white and blue sheets on your side of the
room
Fluid Balance Game Continued
ACTIVITY:
1.
Split class into 2 groups (room will be split into two halves)
2. Each group will have 9 white balls of paper and 9 blue balls of paper
3. The students need to keep the balance by throwing the white sheets
of paper over to the other side, or running the blue sheets of paper
over to the other side.
4. Teacher will periodically throw in balls of paper to ensure that the
students are moving around to maintain the balance.
POST-ACTIVITY JOURNAL REFLECTION:
 Students to write a reflection about what they learned during the game
and how it clarified their understanding of fluid balance
Dehydration Case Study
 How long can we survive without water?
 Examine physiological response to dehydration and
starvation from the real-life report of a girl discovered 15
days after an earthquake devastated Port Au-Prince,
Haiti, in January 2010
 Students are asked to work through the pathways of
water loss from dehydration as they examine the
multiple systems involved in homeostatic responses,
and then are asked to calculate whether it is possible for
a human to withstand 15 days without water
http://sciencecases.lib.buffalo.edu/cs/files/dehydration.pdf
2. Blood Pressure
 Blood volume is regulated by the
hormone aldosterone
 Aldosterone affects the rate of
sodium ion reabsorption, which in
turn affects the rate of water
reabsorption
 Increased aldosterone ➔ increased
water reabsorption ➔ higher blood
pressure
 Decreased aldosterone ➔ decreased
water reabsorption ➔ lower blood
pressure
3. Blood Composition
 Useful materials contained in the
filtrate (glucose, amino acids, etc.) are
reabsorbed until the threshold level of
the given material is reached
 Defined as the maximum amount of
material that can be moved across the
nephron back into the blood
 When the threshold is reached, the
remaining material is removed as
waste e.g. glucose in diabetes
4. Blood pH
 Should be close to 7
 The kidney removes excessively acidic or basic
substances from the blood
Four-Corners Activity
Discuss why waste management is an
important part of any functioning
system – from computers, to cities, to
living things.
5. Waste Removal
 Urea is the major waste
product removed from the
kidneys
 Placed in the blood by the
liver through the detoxification
process
 Excess amino acids are broken
down in the liver
 Converted to ammonia and then
to urea
Urine Formation in the Nephron
Urination Videos
 An excellent review of Urine Formation:
http://www.learnerstv.com/animation/animation.php
?ani=238&cat=biology
 A good overview of the Micturition Reflex:
http://highered.mcgrawhill.com/sites/0072507470/student_view0/chapter26/ani
mation__micturition_reflex.html
Student Activity: Create a Model of
the Excretory Filtering System
Taken from p. 343 of Nelson Biology 12 (2003)
Materials: funnel, aquarium charcoal, 2 small beakers,
food colouring, non-absorbent cotton, ring stand
Place a small piece of non-absorbent cotton in a funnel. Fill
the funnel with aquarium charcoal, and put a small beaker
beneath the funnel. Fill a second beaker with about 25 mL of
water, and add five drops of food colouring. Pour the
coloured water through the funnel and collect it in the beaker
beneath as shown in Figure 2.
Compare the colour of the filtered water with the original
coloured water. Predict what will happen if the water is
filtered once again. Test your prediction. How would you
improve the filter?
Urinalysis Virtual Lab
http://biologyonline.us/Online%20A&P/AP%202/Northland/AP2l
ab/Lab%201%20online/lab4/9.htm

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Test urine samples for disease or infection
Identify symptoms that may lead to a urine test
Learn the role of urine tests in monitoring diseases
Perform three analyses:
1) macroscopic observations
2) chemstix analysis
3) microscopic observations
(*lab can be downloaded from site)
Student Misconceptions
Misconception
Fact and/or Guidance
Students may think that when a body is in homeostasis, no
change takes place and the internal conditions are stable.
Human body systems are constantly active, constantly
monitoring and responding to changing conditions.
“Normal” bodily constants remain the same for all people in
all situations.
• Young children, the elderly, and heavy individuals find it
more difficult to regulate body temperature making
themselves more susceptible to internal and external
stress.
• Body temperature also varies with time, place, and
activity level.
• “Normal” blood pressure also differs. Children tend to
have lower blood pressure than adults, due to the
flexibility of their arteries.
They urinary system is an open system allowing entry of any
substance from the blood stream.
The blood maintains enclosed in vessels but various
substances are allowed to move in and out via filtration.
Students can often be confused by the many ways that the
kidneys maintain homeostasis.
“The Kidney and Homeostasis” chart provided in the
‘References’ portion of the Summary is an excellent tool for
categorizing the mechanisms the kidney uses to maintain
homeostasis. Creating a mind map is also a good way to
distinguish the different mechanisms.
Real-Life Applications
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Kidney Stones
Bright’s Disease
Diabetes Mellitus and Diabetes Insipidus
Renal failure
Effects of performance-enhancing drugs on homeostasis
Effects of energy drinks on homeostasis
Effects of alcohol and illegal drugs on homeostasis
Kidney Dialysis
Diuretics
Kidney transplants and wait times
The effects of chemotherapy on homeostasis
Debate
Should kidney sales be legalized?
Based on the newspaper article:
“Why Legalizing Organ Sales Would Help to Save Lives, End
Violence” - The Atlantic, Nov. 9/11
http://www.theatlantic.com/life/archive/2011/11/why-legalizing-organ-sales-would-help-to-savelives-end-violence/248114/
Other Activities
 Create a model of the kidney
 Jigsaw activity with hormones involved in kidney
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
homeostasis
Create a mind map on kidney homeostasis
RAFT writing activity on kidney transplant waiting list
Prepare a poster campaign on effects of performance
enhancing drugs and drinks on kidney homeostasis
Create flowcharts for hormonal responses
Create a song about kidney homeostasis
Stations about applications of kidney homeostasis
What foods have an impact on urine odour and colour?
Differentiated Assessment
Please refer to previous slides for details:
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Diagnostic Assessment (KWL Chart)
Think-Pair-Share
Student-Teacher Conference
Journal Reflection
Game
Create a Model
Laboratory Reports
Case Study
Debate
Oral Communication
Writing Assessment
Mind Map
Flow Charts
Create a song
Tests & Quizzes
Safety Considerations
 Due to health concerns, it may not be appropriate for some
students to participate in an experiment which involves the
consumption of diuretics.
 Be sure that students do not exceed their normal coffee
intake.
 Allow the option of students to research the topic or
interview others about the topic
 The Fluid Balance Game can be dangerous as it involves
students moving around the classroom and throwing
objects. The activity should be played in an open area
where there is room to move. Ensure that you are
supervising the activity at all times.
Resources
Online Resources:
 Article about how human waste is recycled in Outer Space:
http://science.nasa.gov/science-news/science-at-nasa/2001/ast03apr_2
 Intro to Homeostasis Video:
http://www.learnerstv.com/animation/animation.php?ani=241&cat=Biology
 Micturition Reflex Video: http://highered.mcgrawhill.com/sites/0072507470/student_view0/chapter26/animation__micturition
_reflex.html
 Overview of Kidney Filtration Video:
http://health.howstuffworks.com/human-body/systems/kidneyurinary/adam-200032.htm
 Interactive Video of Kidney Function:
http://www.kscience.co.uk/animations/kidney.swf
 Negative Feedback Loop Animation:
http://bcs.whfreeman.com/thelifewire/content/chp42/4202s.swf
 Urination Video:
http://www.learnerstv.com/animation/animation.php?ani=238&cat=biology
Resources Continued
 Intro to Homeostasis GIZMO:
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http://www.explorelearning.com/index.cfm?method=cResource.dspDetail&Resour
ceID=519
Dehydration Case Study:
http://sciencecases.lib.buffalo.edu/cs/files/dehydration.pdf
Virtual Urinalysis Lab (can be downloaded from site) – involves testing urine
samples for diseases:
http://biologyonline.us/Online%20A&P/AP%202/Northland/AP2lab/Lab%201%20
online/lab4/9.htm
Introduction to Homeostasis Video:
http://www.learnerstv.com/animation/animation.php?ani=241&cat=biology
Urine Formation chart:
http://www.clickandlearn.org/Bio/Gr12Bio/Homestasis.htm
Textbook:
 Blake, et al. Biology 12. Toronto: McGraw-Hill Ryerson, 2002.