Creating a Functional Model of the Excretory System

How to make a working model of excretory system


The excretory system plays a vital role in maintaining the body’s internal balance by eliminating waste products and excess substances. Creating a working model of the excretory system not only enhances our understanding of its intricate functions but also offers a hands-on educational experience. In this article, we will guide you through the process of constructing a unique and informative working model of the excretory system.

Materials Needed

To begin, gather the following materials

1. Plastic bottles (2)

2. Rubber tubing

3. Red and yellow food coloring

4. Plastic container

5. Clay or playdough

6. Small beads (representing waste molecules)

7. Hot glue gun

8. Water

9. Scissors

Model Construction  

Building the Kidneys

Start by taking one of the plastic bottles and labeling it as the “kidney.” Using the hot glue gun, attach rubber tubing to the bottom of the kidney bottle to represent the ureters. The ureters serve as channels through which urine travels from the kidneys to the bladder. Attach the other ends of the tubing to the plastic container, which will represent the bladder.

Simulating Filtration

Fill the kidney bottle with water and add a few drops of red food coloring. The water symbolizes blood, while the red food coloring represents waste molecules filtered from the blood. Place the kidney bottle on a raised platform to allow the water to flow through the tubing into the bladder. This simulates the filtration process that occurs in the kidneys.

Modeling the Nephrons

Use clay or playdough to create small structures inside the kidney bottle, representing nephrons. Nephrons are the functional units of the kidney responsible for filtering blood and forming urine. Mold the clay to resemble small tubules, and ensure they are partially submerged in the water. These structures play a crucial role in filtering waste from the blood.

Demonstrating Concentration

In the other plastic bottle (representing the bladder), add water and a few drops of yellow food coloring. The yellow color indicates that the water in the bladder contains waste products. This step demonstrates how the excretory system concentrates waste substances in the urine, resulting in its distinct color.

Simulating Urination

Once the bladder is filled with the colored water, gently press the bladder bottle. This action represents the muscular contractions of the bladder during the process of urination. Watch as the colored water travels back through the tubing into the kidney bottle, demonstrating the body’s ability to eliminate waste.

Educational Insights

Creating this working model provides several educational insights

1. Filtration Process The model illustrates the filtration process that occurs in the kidneys, emphasizing how waste molecules are separated from blood.

2. Nephron Function By representing nephrons with clay structures, the model showcases their role in filtering blood and forming urine.

3. Concentration Mechanism The color change in the bladder’s water demonstrates the concentration of waste products in urine.

4. Muscular Action The bladder’s muscular contractions during urination depict the body’s controlled expulsion of waste.

5. Hands-on Learning Building the model offers a hands-on approach to learning, making the concept of the excretory system more tangible and memorable.

Frequently Asked Questions

How do you describe the excretory system for a model?

Capillaries (a type of blood vessel) of kidneys filter the blood. All needful substances will be reabsorbed back into the body and waste materials will be converted into urine. Urine thus formed will be passed to the urinary bladder via ureter. Through the urinary opening at the urethra, we excrete urine.

How do you introduce the excretory system?

Introduction. The excretory system is a vital biological system that removes excess and waste products from the body to maintain homeostasis. Most of these products are in fact used and broken down components of metabolism that leave the body in the form of urine, sweat, or feces.


Constructing a working model of the excretory system provides a unique and informative way to understand its complex functions. Through the simulation of filtration, concentration, and urination, this model offers valuable insights into how the body maintains internal balance by eliminating waste products. Engaging in such hands-on learning experiences fosters a deeper understanding of biological processes, making science both fascinating and accessible.

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