Do your students have a difficult time understanding the filtering mechanism of the nephron in the kidney? Don’t feel alone then, most students have a difficult time wrapping their brains around this as it can be quite complex. Here is a simple activity that might bring some clarity for some of the abstract concepts of filtration, reabsorption, and secretion.
Here’s what you’ll need (all can be purchased from Walmart or Target):
Mesh ribbon (or I have seen plastic latch hook stuff used- anything with fairly large holes)
Clear cups (or styrofoam bowls)
Plastic spoons in 3 colors
Beads in several colors and sizes (large red – for rbc; large white- for wbc; large berry beads- for proteins; small red- for amino acids, green- for glucose, blue- for salt, yellow or gold- for urea- **Colors of small beads aren’t that important, just make sure to match 3 of these to the color of the spoons)
- Large Red Beads Red Blood Cells
- Large White Beads White Blood Cells
- Large “Berry” Beads Proteins
- Small Red Beads Amino Acids
- Small Green Beads Glucose
- Small Blue Beads Salt
- Small Yellow/Gold Beads Urea
- Red Spoon Amino Acid Transporter Protein
- Green Spoon Glucose Transporter Protein
- Clear Spoon Salt Transporter Protein
- Clear cup or styro bowl Nephron
- 2 clear cups Blood in Renal Artery and Renal Vein
- Mesh Ribbon/ Plastic Canvas Glomerulus
What to do:
1. Pour the “blood” components into the Renal Artery cup and add water. Lay the “glomerulus” screen over the nephron cup/bowl.
2. Pour the “blood” from the Renal Artery over the top of the “glomerulus” screen to form a single layer. Some of the smaller components will fall through and many large ones will stay on the top of the screen.
3. Pour the large materials that stay on top of the “glomerulus” filter into the Renal Vein cup.
4. To model complete reabsorption- Use the “transport protein” spoons to return all of the glucose and amino acids from the “nephron” bowl to the Renal Vein cup.
5. To model selective reabsorption- Use the “transport protein” spoons to return 5 salt molecules to the Renal Vein cup.
6. Transfer enough water from the “nephron” to fill the cup halfway. **Giving each group of students a different starting amount of water is an excellent way to model how drinking more water produces more urine.
7. Things that didn’t have a transport spoon– are excreted as urine.