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S BI4U Kidney Homeostasis. 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

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S bi4u kidney homeostasis

SBI4UKidney Homeostasis

Jennifer McFarlane

Lorraine Garofalo

Curriculum expectations
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 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

How does the body maintain a stable state
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 & Virtual Lab: Introduction to Homeostasis


  • Explains homeostasis for students learning the topic for the first time



  • As external temperature and internal water and blood sugar levels change, adjust factors to maintain internal stability.


Negative feedback loop
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
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.


Positive feedback loop
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
Bodily Constants

  • Blood glucose concentration = ~ 100 mg/mL

  • Blood pressure = ~ 160/106 KPa(120/80 mm Hg)

  • Body temperature = ~ 37ºC

  • Blood pH = ~ 7

S bi4u kidney homeostasis


An excellent review on the Functions and Structure of the Kidney and the Nephron:


Structure & Function of the Kidney

Think pair share opening activity
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).

S bi4u kidney homeostasis

thirst high blood pressure

food poisoning abnormal blood composition

How does the body respond to internal and external stresses?

Diagnostic assessment
Diagnostic Assessment high blood pressure

  • 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
What high blood pressurerole do the kidneysplay in homeostasis?

The kidney and homeostasis
The Kidney and Homeostasis high blood pressure

  • The kidney maintains homeostasis by regulating the following mechanisms:

    • Water Balance

    • Blood Pressure

    • Blood Composition

    • Blood pH

    • Waste Removal

Water balance inquiry activity
Water Balance Inquiry Activity high blood pressure

The Physiological Effects of Coffee

Physiological effects of coffee
Physiological Effects of Coffee high blood pressure

  • 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


    • Students can interview family/friends who drink coffee

      (Activity taken from McGraw-Hill Ryerson, 2002, Biology 12, pp. 118-119)

1 water balance
1. Water Balance high blood pressure

  • 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
Fluid Balance Game high blood pressure


  • To help students gain a better understanding of fluid balance in the nephron

  • To provide students with a fun and kinesthetic learning opportunity


  • 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


  • to keep an equal balance of white and blue sheets on your side of the room

Fluid balance game continued
Fluid Balance Game Continued high blood pressure


  • 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.


  • Students to write a reflection about what they learned during the game and how it clarified their understanding of fluid balance

Dehydration case study
Dehydration Case Study high blood pressure

  • 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


2 blood pressure
2. Blood Pressure high 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
3. Blood Composition high blood pressure

  • 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
4. Blood pH high blood pressure

  • Should be close to 7

  • The kidney removes excessively acidic or basic substances from the blood

Four corners activity
Four-Corners Activity high blood pressure

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

5 waste removal
5. Waste Removal high blood pressure

  • Urea is the major waste

    product removed from the


  • 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
Urine Formation in the Nephron high blood pressure

Urination videos
Urination Videos high blood pressure

  • An excellent review of Urine Formation: http://www.learnerstv.com/animation/animation.php?ani=238&cat=biology

  • A good overview of the Micturition Reflex:


Student activity create a model of the excretory filtering system
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
Urinalysis Virtual Lab System


  • 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)

Real life applications
Real-Life Applications System

  • 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 System

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


Other activities
Other Activities System

  • 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?

Differentiated assessment
Differentiated Assessment System

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

Safety considerations
Safety Considerations System

  • 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 System

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.mcgraw-hill.com/sites/0072507470/student_view0/chapter26/animation__micturition_reflex.html

  • Overview of Kidney Filtration Video: http://health.howstuffworks.com/human-body/systems/kidney-urinary/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
Resources Continued System

  • Intro to Homeostasis GIZMO: http://www.explorelearning.com/index.cfm?method=cResource.dspDetail&ResourceID=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%20online/lab4/9.htm

  • Introduction to Homeostasis Video: http://www.learnerstv.com/animation/animation.php?ani=241&cat=biology

  • Urine Formation chart:



  • Blake, et al. Biology 12. Toronto: McGraw-Hill Ryerson, 2002.