Your Heart Pumps 8,000 Liters a Day! The Secret of “Valves” Revealed Through a Kerosene Pump
I’m Ken Kuwako, a Science Trainer. Every Day Is an Experiment!
“Thump, thump…” Our hearts have been working tirelessly from the moment we are born, never taking a break. You might be surprised to learn that this small organ, about the size of a clenched fist, pumps out roughly the equivalent of 40 large drums of blood every day. Textbooks tell us that “the heart has four chambers and valves that prevent blood from flowing backward,” but simply reading that explanation can leave many middle school students thinking, “I kind of get it… but not really.”
That’s exactly when experiments can make all the difference. Believe it or not, you can experience the ingenious mechanism of this life-sustaining pump using just one familiar household item. In this article, I’ll introduce a heart model experiment using a kerosene siphon pump, which I developed together with student teachers.
Kerosene siphon pumps are available at Seria and Daiso.
Why Does Blood Flow in Only One Direction? Solve the Mystery with an Everyday Tool!
For an adult weighing around 50 kg, the amount of blood circulating through the body is said to be about 4 liters.
By contrast, each heartbeat pumps out about 60–80 milliliters of blood in an adult. Let’s use 70 mL as an example. If the heart beats 80 times per minute (the typical range is said to be 60–100 beats per minute), we can calculate the amount of blood pumped by the heart in one day as follows.
70mL × 80 beats/min × 60 min × 24 hours
70 × 80 = 5,600 mL (per minute)
5,600 × 60 = 336,000 mL (per hour) = 336 L
336 × 24 = 8,064 L
In other words, the heart pumps around 8,000 liters of blood every day!
There are only about 4 liters of blood in the body, yet the total amount pumped in a day is about 2,000 times that much. The reason for this huge difference is the fact that the blood continuously circulates around the body again and again. The heart isn’t constantly making new blood. Instead, it keeps circulating the same limited supply of blood over and over at an astonishing rate.
When we think of a kerosene siphon pump as a model of the heart, we can clearly see the role of the tiny “valve” inside the pump. And that little valve turns out to be the key to understanding how the heart works.
Experiment Setup: Build a Life-Saving Pump with a 100-Yen-Shop Item
The materials are incredibly simple. You can easily find everything you need at home or at a 100-yen shop.
【What You’ll Need】
- Two kerosene siphon pumps:
- One with the valve removed
- One with the valve left in place
- Water and red food coloring (to create “blood”)
- A transparent beaker or container (so you can easily observe the flow of the “blood”)
- A tray or towel (to keep your table from getting wet)
【Experiment Procedure】
Prepare some “blood” by adding red food coloring to water. First, let’s see what happens when you operate the pump with the valve removed.
→ Whether you push or pull the pump, water flows in and out through both hoses. The result? The “blood” can’t travel around the body in a single direction. Next, try the same thing with the regular pump with its valve in place.
→ This time, something amazing happens: the water is pumped forcefully in one direction. There is no backflow at all. This is exactly what makes the flow of life possible, carrying oxygen and nutrients throughout the body!
See It, Feel It, Understand It! The Valve Is the Real Hero of the Heart
The greatest appeal of this experiment is that you can actually experience the realization, “Ah, without this valve, the blood couldn’t circulate!” rather than simply learning it as a fact from a textbook.
Without the valve, the water just moves back and forth. Add the valve, and suddenly it produces a strong, one-way flow. Once you see this dramatic difference with your own eyes, it becomes completely natural to think, “So that’s why the heart needs valves!”
Inside our bodies, valves performing the same basic function open and close accurately around 100,000 times a day, keeping the rhythm of life going. Both the astonishing figure of 8,000 liters and the incredible 100,000 opening-and-closing cycles are ultimately possible because the valves are doing their job properly. It’s amazing how many opportunities for scientific wonder are hiding in such ordinary objects.
【Quick Tip】Choosing the Right Pump for a Successful Experiment
There’s actually a little trick to choosing the right pump for this experiment. Products from 100-yen shops work perfectly well, but the visibility of the valve varies depending on the manufacturer.
Seria pumps: The valve is colored red, making its movement easy to see and ideal for observation.
Daiso pumps: The valve is often transparent, so it may be a little harder to see.
If you have a chance to choose one in the store, take a peek inside the pump and check the color of the valve. The fun of science isn’t just about memorizing facts. It’s about using familiar objects to ask “Why?” and then having that wonderful “Aha!” moment when everything suddenly makes sense. I hope you’ll enjoy this experience at home or in your classroom!
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