The human body is truly fascinating. Many become doctors because they want to help people, but also because they find working with the human body to be so interesting! We have a simple step-by-step science project that is great for fostering an interest in the human body with children—how to make your own DIY heart pump. This heart pump model would also make a great science fair project!
Use these simple human body activities in your homeschool and learn how the amazing muscles that make your heart work bring blood flow to your organs every day. Make a pump using a jar, a balloon, and two straws to get an idea of how your heart pumps blood through your circulatory system.
Children under 8 can choke or suffocate on uninflated or broken balloons. Use adult supervision and keep uninflated balloons from children. Discard broken balloons at once.
What You Do:
- Fill the jar half full of water.
- Cut the neck of the balloon off at the part where it starts to widen into a balloon. Set the neck part aside.
- Stretch the balloon over the opening of the jar, pulling it down as tightly as you can. The flatter you can get the surface of the balloon, the better.
- Carefully use the tip of a skewer to poke two small holes in the surface of the balloon. Make them about an inch apart from each other and near opposite edges of the jar.
- Stick the long part of the straw into each hole. The straws should fit securely in the holes so no air can get through around the straws.
- Slide the uncut end of the balloon neck onto one of the straws and tape it around the straw.
- Set your pump in a large pan or the sink to catch the pumped water. Bend the straws downward. Gently press in the center of the stretched balloon and watch what happens to the water in the jar.
You made a simple pump that moved water from the jar through the straws and into the pan. The cut end of the balloon worked as a valve to stop the water from going back down the straw. Your heart pumps blood out into your body through your arteries in a similar way.
Human hearts have four separate chambers inside. This heart model pump shows how one chamber and its valve works.
A valve is used to keep blood that has been pumped from one chamber to another from flowing back into the chamber it came from.
Try taking the balloon valve off of the straw and pump water again. Did you notice anything different? You likely saw that water still came out of the straw, but without the valve, there was nothing to keep some water from going back down the straw.
In order to keep blood moving through your blood vessels and into your body, your heart needs valves to separate its chambers.
The original project can be found here.
How to Hear Your Heartbeat
Have you ever heard your heart? How about someone else's heart? Doctors use an instrument called a stethoscope to listen to your heartbeat. In this experiment, you can listen to your heartbeat with a stethoscope as doctors use, or make your own simple stethoscope.
What You Need:
- A partner to help you
- Cardboard tube from a paper towel roll
- Stopwatch or minute timer
- Pencil and paper
What You Do:
- Have your partner sit or stand still, so you can listen to their heartbeat. Place the stethoscope's sensor heard or one end of the cardboard tube on your partner's chest, slightly to the left. Place the earpieces in your ears. Or, if using a cardboard tube, put your ear up to the other end of the tube. Listen carefully. Do you hear a steady beat? Move the tube around until you can find the heartbeat.
- Once you have found a steady heartbeat, set the stopwatch for one minute, and hand it to your partner. Start counting your partner's heartbeats as soon as your partner presses 'Start' on the stopwatch.
- At the end of one minute, write down how many heartbeats you were able to count.
- Have your partner repeat steps 1-3 while listening to your heart.
- Now, have your partner exercise for 15 minutes. Examples of this are: jogging around the house, jumping on a trampoline, and walking up and down the stairs. The key is not what your partner does, just that the activity is continuous for 15 minutes without stopping for a break.
- After 15 minutes of exercising, measure your partner's heartbeat, counting how many beats there are during one minute. Write this new number down. Is it different from the number before?
- Now it's your turn to exercise! Do the same activity that your partner did for 15 minutes without stopping for a break.
- Once you've finished, have your partner count how many times your heart beats in one minute. Write the new number down.
Exercise makes our heart beat faster. When our bodies are working harder, we need a steady blood supply.
Our hearts provide blood to all parts of the body, even our brains! When we exercise, it also exercises the heart!
Our hearts have to work a lot harder to pump blood while we are exercising. Our blood contains oxygen, which we need during exercise. As we use up the oxygen that our blood supplies, our heart has to keep pumping new blood into our system.
Even after you were done exercising, your heartbeat was still faster than normal. This is because as your body cools down, you still need a strong oxygen supply. You can try the experiment again with less exercise (5 minutes) or more exercise (30 minutes).
What are some times when your heartbeat really fast? Why do you think that is? Sometimes something scary like riding a roller coaster will make our hearts beat fast.
Heart Science Lesson
Did you know that your heart is made up of muscles? Not just any muscles, though! The muscles that keep your heart pumping are called cardiac muscles. They are particularly strong and can work constantly without becoming tired or sore the way other muscles often do.
Cardiac muscles are involuntary muscles, which means that they work whether you think about them or not. Think about the muscles in your arm. If you want to pick something up, you have to use your muscles to move your arm. Those muscles are voluntary muscles because you can control them.
The muscles that keep your heart pumping are involuntary because you cannot control them. It's a good thing because if you forgot to tell your cardiac muscles to pump blood, even for a moment, it would cause a lot of problems for the rest of your body!
Human hearts have four chambers and work as a pump constantly delivering blood to the body.
Deoxygenated blood—which needs a fresh supply of oxygen—is brought by veins in from the body into the first chamber, known as the right atrium. The heart then pumps the blood through the first valve and into the right ventricle. Then it is pumped through the next valve and off to the lungs through a large artery.
In the lungs, the blood receives oxygen. From the lungs, the oxygenated blood is brought back to the heart. The blood passes through the left atrium through another valve and into the left ventricle; from there it is pumped through yet another valve into arteries to be taken to the rest of the body.
This process of pumping blood through the body is called circulation and it repeats itself all day, every day throughout your life! Valves act like doors in your heart, controlling how much blood goes in and out. The beating sound your heart makes comes mostly from the valves opening and closing.
Can you think of any other examples of a pump? How about the pump on a soap bottle? A pump like that also has a valve inside that allows the soap to come out of the tip rather than sliding back down the tube.
How about other kinds of valves? A faucet has a valve that can close off to control how much or how little water comes out. When you turn the faucet's knobs, you control the valve. A sports drink bottle also has a valve that allows water out, but you can't pour water back in through it.
The Human Heart
Human hearts have four chambers and work as a pump delivering blood to your body.
Deoxygenated blood—which needs a fresh supply of oxygen—is brought by veins in from the body into the first chamber, known as the right atrium. The heart then pumps the blood into the right ventricle, and from there it is pumped to the lungs. In the lungs, the blood receives oxygen.
From the lungs, the oxygenated blood is brought back to the heart. The blood passes through the left atrium into the left ventricle, and from there it is pumped through your arteries to the rest of the body. Check out our heart worksheet to test your knowledge of the five basic parts of the heart.
The largest artery in the body is the aorta and it's located above the left ventricle. This process of moving blood through the body is called circulation and it repeats itself all day, every day throughout your life!
When you were exercising, you needed more oxygenated blood, so your heart had to work harder! That's why it beat faster after exercise. The sound of your heartbeat is the sound of valves in your heart closing. Valves act like doors in your heart, controlling how much blood goes in and out.
Blood's circulation path: body → veins → right atrium → right ventricle → lungs → left atrium → left ventricle → arteries → body