Hands-on Activity If You're Not Part of the Solution, You're Part of the Precipitate!

Learning Objectives

After this activity, students should be able to:

• Describe the importance of research in technological advancements.
• Explain the importance of maintaining body chemistry homeostasis.

Educational Standards

Each TeachEngineering lesson or activity is correlated to one or more K-12 science, technology, engineering or math (STEM) educational standards.

All 100,000+ K-12 STEM standards covered in TeachEngineering are collected, maintained and packaged by the Achievement Standards Network (ASN), a project of D2L (www.achievementstandards.org).

In the ASN, standards are hierarchically structured: first by source; e.g., by state; within source by type; e.g., science or mathematics; within type by subtype, then by grade, etc.

NGSS: Next Generation Science Standards - Science

International Technology and Engineering Educators Association - Technology

State Standards

Materials List

Each group needs:

• calcium chloride (CaCl ), granular, available for $6.85 for 500 g at https://www.flinnsci.com/calcium-chloride-anhydrous-500-g/c0016/
• potassium phosphate (KPO₄) reagent grade, crystal, available for $12.80 for 100 g at https://www.flinnsci.com/potassium-phosphate-monobasic-reagent-100-g/p0141/
• 200 ml distilled water
• 2 beakers (one for the CaCl solution, and one for the KPO₄ solution)
• stirring rod or spoon
• marker and masking tape, for labeling the beakers
• safety glasses, pair per student
• Osteopontin Research Activity Worksheet, one per student (students should already have this worksheet and have completed page 1 during the associated lesson)

Note: Chemical and lab materials available at science supply stores such as Flinn Scientific at https://www.flinnsci.com/

To share with the class:

• computer with projector, to show the presentation
• Pharmaceutical Research Presentation (a PowerPoint file)

Worksheets and Attachments

Pre-Req Knowledge

Conduct the associated lesson before starting this activity.

Having background knowledge of the human body (as studied in anatomy) makes this activity a richer experience, for example, an understanding of the importance of body chemistry and electrolytes, and basic knowledge of the functioning of each body system.

Introduction/Motivation

Yesterday, we reviewed and practiced what biomedical engineers do during the research phase of the engineering design process, and today we are going to use the information we gathered to determine what the exact effects Osteopontin has on the body, and what health complications might occur in humans if we were to administer this drug.

(Spend a few minutes reviewing the answers to the three exit questions students completed the previous day as part of the associated lesson.)

We will begin by conducting a simple experiment to see what happens when solid calcium precipitates out of solution, and then think about how this may apply to the solutions present in our bodies.

Procedure

Background

During the associated lesson, Pharmaceutical Research Design Problem, students read a scholarly article to learn what other researchers have already discovered about Osteopontin in the human body. During this activity, students continue the research phase of the engineering design process as it relates to developing a new pharmaceutical drug by conducting a simple illustrative lab experiment.

Once the lab experiment is done, use the Pharmaceutical Research Presentation to show students photographs of a precipitate as well information on forming a precipitate and research implications to help wrap up a discussion of how this change in calcium may affect the human body.

Before the Activity

• Gather materials and lab supplies.
• From conducting the associated lesson, students should already each have an Osteopontin Research Activity Worksheet with page 1 completed.
• Prepare two solutions for each group, as described below. Note: The goal is to mix enough of each solid with 100 ml of distilled water so that it all dissolves and no solid remains in the bottom of the beaker. Start with a small amount (the size of a quarter) and add more until it takes some time for it all to dissolve. The more saturated the solution, the more precipitate will form. It may take 5-10 minutes of stirring to get it to dissolve. Add a little at a time to make sure it all dissolves and when it starts to take a long time to dissolve, stop adding and continue stirring until all the solid is dissolved.

1. In one beaker, add 100 ml of distilled water. Add CaCl₂ slowly and stir vigorously to dissolve the CaCl₂. It may take 5-10 minutes of stirring until the solid dissolves to produce a saturated solution of CaCl₂. Use a marker and a piece of masking tape to label the beaker: Ca⁺ and Cl^-.
2. In the other beaker, add 100 ml of distilled water. Add K₃PO₄ slowly and stir vigorously to dissolve the K₃PO₄. It may take 5-10 minutes of stirring until the solid dissolves to produce a saturated solution of K₃PO₄. Use a marker and a piece of masking tape to label the beaker: K⁺ and PO₄ ^-.

• Be ready to show the class slides 10-15 of the Pharmaceutical Research Presentation. (Note: Slides 1-9 should have been presented during the associated lesson.)

With the Students

1. Distribute a Ca⁺,Cl^- and a K⁺, PO₄ ^- beaker, stirring rod and safety glasses to each group.
2. Direct students to carefully mix the two solutions together and stir.
3. It may take five minutes or so for the precipitate to form. Expect the solution to appear cloudy.
4. Direct students to stop stirring and observe as the solid falls out of solution.
5. Have students record their observations on their worksheets.
6. Facilitate a discussion of the phenomenon. A double replacement reaction occurred with the following balanced equation: 3 CaCl₂ + 2 K₃PO₄ = Ca₃(PO₄)² + 6 KCl and solid calcium phosphate precipitated out.
7. Remind students that we humans have all of these ions in our blood at all times. Certain molecules, like Osteopontin, help keep them in solution.
8. Have students draw on their article research from the lesson to discuss worksheet questions 3 and 4 in their groups, and write down their answers.
9. Bring together the class and show students slides 10-15 of the presentation to wrap up the activity.
10. On slide 11, have students use their knowledge of anatomy to postulate what happens in the blood, urine and blood vessels when calcium salts precipitate out of solution. Biomedical engineers must have a good knowledge of anatomy and/or conduct further research to understand reactions consequences in the human body.
11. Read slide 12 to students, the resulting research implications for what happens in the blood, urine and joint fluid.
12. Show the remaining slides, which talk about vascular calcification and include images of kidney stones and gout.
13. Facilitate a discussion of the effects of solid calcium salts on the blood, urine and synovial fluid. Expect students to use their knowledge of the human body to contemplate potential health complications from calcium salts forming in each of these three fluids.

• In the blood, solid calcium can cause calcifications to occur, such as the depositing of solid calcium into vessel walls, making them hard and inflexible.
• In urine, solid crystals can lead to the formation of crystals and eventually kidney stones.
• In joint fluid, crystals can develop from the solid calcium causing inflammation and pain (gout).

14. Conclude by collecting the completed worksheets and assigning the exit questions, as described in the Assessment section.

Vocabulary/Definitions

biomedical engineering: The application of science, math and engineering principles to problem solving design that involves medicine and biology.

dissociate: A general process in which ionic compounds separate or split into smaller particles or ions, usually in a reversible manner.

electrolyte: Any substance that dissociates into ions when dissolved in a suitable medium.

engineering design process: A series of steps used by engineering teams to guide them as they develop new solutions, products or systems.

homogenous: Uniform in structure or composition.

precipitate: To separate (a substance) in solid form from a solution.

solution: A homogeneous, molecular mixture of two or more substances.

Assessment

Opening Review: Begin the activity by reviewing with the class their answers to the exit questions from the associated lesson, conducted the previous day. Clarify any misconceptions.

Observations: During the lab activity, observe student progress. Make sure students are following instructions accurately, completing their worksheets (page 2) and participating in discussions.

Worksheet: At activity end, collect the Osteopontin Research Activity Worksheets with students' research notes on page 1 (from the lesson) and lab observations and conclusions on page 2. Review their notes and answers to assess their understanding of the subject matter.

Written Exit Questions: To conclude, assign students to individually answer the following questions and submit for points. The next day, review the answers with students to clarify any misconceptions.

1. Why is the maintenance of stable body chemistry important? Do you find this surprising? (Answer: Even a slight change in body chemistry can initiate a chain reaction that causes a diverse set of problems in the body. We do not understand all the chemicals and their complex interactions in our bodies. The natural chemical balance in our bodies is very important and we do not want to disturb it and cause problems.)
2. Describe in your own words how extreme changes in Osteopontin levels can lead to kidney stones. (Example answer: Lowering levels of Osteopontin increases the chance that calcium salts will precipitate out of solution in the body. If solids form during the body's production urine, they can collect in the kidneys where they may become stuck in the tiny tubes. So extreme changes in Osteopontin levels can cause more solids to accumulate until kidney stones form.)
3. (optional; for bonus points) If you were a biomedical engineer, what sort of design projects would you like to work on that would help in the care of human health? (Possible answers: As a medical problem solver, I would like to design medical implants [replacement joints, limbs, tissues or organs], develop pharmaceutical drugs, design surgical tools and methods, create diagnostic equipment, etc.)

Safety Issues

• Make sure students wear safety glasses so chemicals do not splash into their eyes during the lab.
• For all other safety concerns, refer to the MSDS for the chemicals used.

Copyright

Contributors

Supporting Program

Acknowledgements

The curricular material was supported by an NSF CAREER award (grant no. CMMI 1150376) and an NSF RET program (grant no. EEG 0908810) at Michigan State University. However, these contents do not necessarily represent the policies of the National Science Foundation and you should not assume endorsement by the federal government.