SBI4U 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   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 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&ResourceID=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-and-nephron?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-and-nephron?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).

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?

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: 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: 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

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.mcgraw-hill.com/sites/0072507470/student_view0/chapter26/animation__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/AP2lab/Lab%201%20online/lab4/9.htm 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 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 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

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 http://www.theatlantic.com/life/archive/2011/11/why-legalizing-organ-sales-would-help-to-save-lives-end-violence/248114/

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?

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

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.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 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: http://www.clickandlearn.org/Bio/Gr12Bio/Homestasis.htm Textbook:   Blake, et al. Biology 12. Toronto: McGraw-Hill Ryerson, 2002.