Name _____________________________
Kidney Filtration Lab
Introduction: The kidneys function to filter the blood in the body, removing waste, therefore cleansing the
blood. In this experiment, the dialysis bag will act as part of the kidney. The red solution symbolizes blood
as it is entering the kidney via the renal artery. As the experiment progresses, notice the filtration occurring
with the kidney (dialysis tubing) and the resulting substances.
Materials:
Dialysis tubing
String (2 pieces)
Pipette
(1) 250 mL beaker
(1) 150 mL beaker
10 mL graduated cylinder
Simulated blood
Water
Procedure:
1. Open the piece of dialysis tubing as demonstrated to you by your teacher. Tie one end of it closed
with one piece of string. Test that the dialysis tubing will not leak out of the bottom by placing a
small amount of water into the tubing. If it leaks out the bottom, the string has not been tied tight
enough. Retie it and test again. If/when it does not leak, pour the water out of the tubing into the
sink.
2. Fill your beaker with 200 mL of water. Set this aside for now.
3. Carefully measure out 3 mL of Congo Red using the 10 mL graduated cylinder. Pour it into the 150
mL beaker. Wash out the cylinder.
4. Carefully measure out 3 mL of yellow food coloring using the 10 mL graduated cylinder. Pour it into
the 150 mL beaker. Wash out the cylinder.
5. Measure out 5 mL of water using the 10 mL graduated cylinder. Pour the water into the 150 mL
beaker.
6. Now, take a pipette and mix the solutions in the 150 mL beaker. To do this, place the pipette in the
solution and squeeze and release the bulb of the pipette while moving the pipette throughout the
solution.
7. Once the solution has been thoroughly mixed, use the 10 mL graduated cylinder to measure 10 mL of
the solution into the dialysis tubing. Rinse out the cylinder.
8. Tie the other end of the dialysis tubing shut with the second piece of string. Rinse the outside of the
tube off and place it into the 250 mL beaker with the 200 mL of water. Indicate in the “before” table
where each solution is located at this point in the experiment. (Start your timer first!)
9. Let the dialysis tubing sit in the water for 60 minutes. Notice the diffusion through the dialysis
tubing. Indicate in the “after” table where each solution was located after the experiment.
Data:
Solution
Location of Solutions Before and After the Experiment
Before
After
Location
Color
Location
Color
Congo Red
Yellow Food
Coloring
Analysis:
1. What specific part of the kidney does the dialysis tubing represent? What is this part’s function?
2. What does the yellow food coloring represent at the end of the experiment? What does the Congo
red represent?
3. Why is it important that the kidney filters the blood?
4. If a person’s kidneys stop working, they must get dialysis treatments several times a week. Explain
how this treatment would work – refer to what you saw in the lab to be able to answer this question.
Conclusion: Write a paragraph (5 – 7 sentences) summarizing what you learned about kidney function
through this lab and what your data from the lab shows.