1. SBI4U Kidney Homeostasis
Jennifer McFarlane
Lorraine Garofalo

2. 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

3. 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

4. Background Information

5. 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.

6. Video & Virtual Lab: Introduction to Homeostasis
Explains homeostasis for students learning the topic for the first time  
GIZMO:
As external temperature and internal water and blood sugar levels change, adjust factors to maintain internal stability.

7. 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.

8. 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.

9. 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.

10. Bodily Constants Blood glucose concentration = ~ 100 mg/mL
Blood pressure = ~ 160/106 KPa (120/80 mm Hg)
Body temperature = ~ 37ºC
Blood pH = ~ 7

11. Structure & Function of the Kidney
VIDEO:
An excellent review on the Functions and Structure of the Kidney and the Nephron:

12. Kidney Homeostasis

13. 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).

14. How does the body respond to internal and external stresses?
thirst high blood pressure food poisoning abnormal blood composition
How does the body respond to internal and external stresses?

15. Diagnostic Assessment
Have students fill out a KWL chart in pairs guide instruction and clear up any misconceptions about kidney homeostasis.

16. What role do the kidneys play in homeostasis?

17. The Kidney and Homeostasis
The kidney maintains homeostasis by regulating the following mechanisms:
Water Balance
Blood Pressure
Blood Composition
Blood pH
Waste Removal

18. Water Balance Inquiry Activity
The Physiological Effects of Coffee

19. 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 )

20. 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

21. 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

22. Fluid Balance Game Continued
ACTIVITY:
Split class into 2 groups (room will be split into two halves)
Each group will have 9 white balls of paper and 9 blue balls of paper
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.
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

23. 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

24. 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

25. 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

26. 4. Blood pH Should be close to 7
The kidney removes excessively acidic or basic substances from the blood

27. Four-Corners Activity
Discuss why waste management is an important part of any functioning system – from computers, to cities, to living things.

28. 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

29. Urine Formation in the Nephron

30. Urination Videos
An excellent review of Urine Formation:
A good overview of the Micturition Reflex:

31. 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?

32. Urinalysis Virtual Lab
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)

33. Student Misconceptions
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.

34. Real-Life Applications
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

35. Should kidney sales be legalized?
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

36. Other Activities Create a model of the kidney
Jigsaw activity with hormones involved in kidney 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?

37. Differentiated Assessment
Please refer to previous slides for details:
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

38. 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.

39. Resources Online Resources:
Article about how human waste is recycled in Outer Space:
Intro to Homeostasis Video:
Micturition Reflex Video:
Overview of Kidney Filtration Video:
Interactive Video of Kidney Function:
Negative Feedback Loop Animation:
Urination Video:

40. Resources Continued
Intro to Homeostasis GIZMO:
Dehydration Case Study:
Virtual Urinalysis Lab (can be downloaded from site) – involves testing urine samples for diseases:
Introduction to Homeostasis Video:
Urine Formation chart:
Textbook:
Blake, et al. Biology 12. Toronto: McGraw-Hill Ryerson, 2002.