We all have blood – but what is it really made of?
You’ve seen the red stuff if you’ve ever gotten a bad paper cut. We need blood to keep our bodies working: it brings air and nutrients to all the organs in our bodies – without it, we wouldn’t be able to do anything. Your body makes blood with special ingredients: red blood cells, white blood cells, platelets and plasma. Each of these ingredients has a certain role in the body.
In this activity, you will learn about the different parts of blood.
| Objectives: Identify the four different parts of blood and state their roles Key Vocabulary: Blood, oxygen, nutrients, red blood cell, white blood cell, platelet, plasma, organs |
Background:
- We need blood to survive. Blood brings air (oxygen) and nutrients to our organs, and helps take toxins and carbon dioxide to the lungs, digestive system and kidneys to be removed from the body
- Blood also carries hormones throughout the body and helps fight infections
- Blood is made up of four major components:
- Red blood cells (aka “erythrocytes”) bring oxygen/air to the body. They are shaped like disks that are slightly indented and contain hemoglobin, a protein that picks up oxygen from the lungs and carries it throughout the body, releasing it to other organs. Red blood cells are produced in bone marrow, the sponge-like center of the bones, and are shaped like donuts so they can easily pass through capillaries.
- White blood cells (aka “leukocytes”) help fight infections. Different types of white blood cells fight different kinds of germs (like bacteria and viruses) and some make antibodies (proteins that recognize foreign materials and help fight them). The body might produce more white blood cells when trying to fight an infection.
- Platelets (aka “thrombocytes”) are responsible for clotting. They are oval shaped and gather around a broken blood vessel to create to help stop the bleeding.
- Plasma is the liquid substance that helps red blood cells, white blood cells, and platelets flow through the blood vessels. It also carries nutrients, hormones and proteins throughout the body.
- The heart pumps the blood throughout the body, sending it to the lungs to pick up oxygen and then through arteries to all our cells. Then, the blood without oxygen travels through veins to go back to the heart and start the process over again.
- We can feel blood pumping on our pulse points (wrist, upper neck, etc.), which are arteries that are close to the skin.
- Sometimes people might not have enough blood cells. They can take medicine to help or get a transfusion, where they can get the part of blood they need (red blood cells, platelets, etc.) from a donor.
- There are eight different types of blood, depending on the types of proteins in the red blood cell.
- There is a popular misunderstanding that deoxygenated blood (low in oxygen) is blue that that blood only turns red when it comes into contact with oxygen. This isn’t true! Human blood is always red. It has a bright red color when oxygenated and a darker red color when deoxygenated. Blood is never blue, but your veins look blue because light is diffused by the skin.
This information and more found on KidsHealth. To find a place to donate blood, please visit the Red Cross. More on Hematology at Children’s National.
Sickle Cell Anemia:
- Sickle cell anemia is a blood disease where the red blood cells are not shaped correctly. Typically red blood cells look like round discs. In people with sickle cell anemia, red blood cells are shaped like crescent moons, or sickles.
- The typical round disc shape of red blood cells helps make sure they can easily move through the body’s blood vessels to deliver oxygen. But when blood cells are sickle shaped, they can get stuck in the blood vessels causing pile ups that block blood flow.
- When blockages happen in the blood vessels, it can cause a lot of pain and even organ damage. People with sickle cell disease have fewer normal red blood cells, so they can also get infections more often and become really tired.
- Sickle cell disease is a genetic condition, meaning it is inherited from parents. It is usually discovered at birth using blood tests. Curing sickle cell anemia can be possible, requiring a complex bone marrow transplant, however, those with the disease can lead pretty normal lives with the help of their doctor.
To learn more about sickle cell disease, please visit St. Jude Children’s Research Hospital and AboutKidsHealth.
Kid Friendly Language:
- Blood flows all throughout our body with the help of our heart.
- We need blood for a lot of things. Blood helps to bring oxygen to different parts of our body and helps to take bad toxins and carbon dioxide out of our body. Blood also helps us fight infections to keep us healthy!
- Blood is made up of four different parts.
- The red blood cells help bring oxygen to different parts of the body. To do this, the red blood cells stop by the lungs to pick up oxygen using a protein called hemoglobin. Then they travel all throughout the body to carry oxygen to your organs. Red blood cells are shaped like round donut-like discs so they can fit through tiny tubes in your body called capillaries.
- The white blood cells help you fight infections when you’re sick. Different white blood cells are made to defend against different germs that make you sick. Some white blood cells make antibodies which help to find and fight germs. When you’re sick, your body might produce more white blood cells than usual.
- The platelets help you stop bleeding. When you get a cut, platelets rush to the cut and plug up the leak, or make a clot, to repair the damage.
- Plasma is the liquidy substance in your blood that carries nutrients, hormones and proteins throughout the body.
- The heart pumps the blood throughout the body. After blood picks up oxygen in the lungs, it goes through tubes called arteries so it can bring the oxygen to organs. Then, the blood without oxygen travels through other tubes called veins to go back to the heart and start the process over again.
- We can feel blood pumping on our pulse points (wrist, upper neck, etc.), which are arteries that are close to the skin.
Key Questions
Materials
- Red pony beads
- White pom poms
- Purple small foam beads
- Water or vegetable oil
- Plastic test tube or clean empty plastic bottle
- Funnel (or the top half of a clean water bottle carefully cut off from the top)
- Hot glue or super glue
Activity Plan
If using tissue or dissolvable paper:
- Connect to prior knowledge:
- Ask: Have you ever fallen down and gotten a cut? Did you need a band-aid? Why?
- Explain: We all have blood inside us. Blood is made of lots of different parts, and each part has a different job. Let’s find out what those jobs are!
- Observe: Look at the veins in your wrist. What color does the blood look like? (Possible response: blue) Some people think that blood without oxygen/air is blue, but that’s not true – human blood is never blue even though it looks that way – it just seems blue because of the way light goes through your skin.
- Find materials that represent different parts of blood. The materials listed for this activity are what we use, but you can use anything with similar shapes, colors and sizes – some people even like to use different kinds of candy! We like to use:
- Red pony beads (red blood cells)
- Small white pom poms (white blood cells)
- Glitter (platelets)
- Water (plasma)
- Using a funnel, add the different blood parts to a test tube, empty plastic bottle, or other container. Use the chart to help decide how much to add.
- Pour enough water in to cover all the materials
- Add some glue to the top of the container and stick it on.
| Part | Representation | Job | Percentage |
| Red blood cell | Red pony beads | Carries oxygen | 45% |
| White blood cell | White beads | Fights infection | <1% |
| Platelet | Purple foam beads | Stops bleeding | <1% |
| Plasma | Water or vegetable oil | Carries nutrients, hormones | 55% |
As with all activities, adult supervision is strongly recommended.
Follow-Up Questions
- Why do you think we have blood?
- Possible Responses: Helps bring air and nutrients throughout the body
- How do you think blood gets around the body?
- Possible Responses: in veins, the heart pumps it throughout
Extension Activities
Make your very own bloodmobile! Try using Legos or recyclable/found materials to build a bloodmobile that can deliver oxygenated blood to different parts of the body!
Do research on an animal with different colored blood and write a short report discussing this animal’s circulatory system.
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