Have you ever thought about blood? It’s something we all have inside us, but did you know that not all animals have red blood like we do? Some creatures, like horseshoe crabs and certain octopuses, have blue blood. There’s even a special lizard with green blood! Isn’t that cool?
Our friend Beckett asked a great question: Why do we need blood? Let’s dive into the answer! Blood travels through tiny tubes in our bodies called blood vessels. These vessels are like highways for blood, and they all connect to the heart. There are two main types of blood vessels: arteries and veins. Arteries carry blood away from the heart to different parts of your body, like your feet, head, and hands. Veins bring the blood back to the heart.
Think of blood’s journey like a racetrack. It goes out from the heart, circles around your body, and comes back again. But why does it do this? Well, blood has some very important jobs!
One of blood’s super important jobs is to carry nutrients from the food you eat to all parts of your body. When you eat, your food gets broken down into tiny nutrients in your stomach and small intestine. Blood picks up these nutrients and delivers them to where they’re needed, helping you grow and stay healthy.
Blood also carries oxygen, which is something your body needs to survive. When you breathe in, your lungs take oxygen from the air. Blood picks up this oxygen and delivers it to your muscles and other parts of your body. Without oxygen, you wouldn’t be able to live for more than a few minutes!
Have you ever noticed that veins look bluish under your skin? Some people wonder if blood changes color. The truth is, blood is always red, but it can look a little darker when it has less oxygen. This darker color can make veins appear bluish, but they’re not actually blue.
Thanks to Beckett for the awesome question about blood! Remember, there are so many mysteries in the world waiting to be explored. Keep asking questions and stay curious. Who knows what amazing things you’ll discover next?
Sure! Here’s a sanitized version of the transcript:
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(phone ringing) – Hi, it’s Doug. Blood is something we all have. Personally, it makes me a little squeamish or lightheaded if I see it. Maybe you’re tougher than I am. I heard that not every living thing has red blood. Some animals, like horseshoe crabs and certain types of octopuses, have blue blood. There’s even a type of lizard that lives on some islands in the Southern Pacific Ocean that has green blood. Isn’t that interesting?
Someone named Beckett has a question about blood. Let’s give them a call now. (phone ringing) – Hi, Doug. – Hi, Beckett! – I have a question for you. Why do we need blood? – That’s a great question. You might have heard that blood flows inside something called blood vessels in your body. These are small tubes that you might even be able to see from the outside. All of these blood vessels connect together at the heart. One set of vessels, the arteries, carries blood away from the heart to all the different parts of your body—down to your feet, up to your head, out to your hands, and to all of your muscles. Then another set of vessels, the veins, takes that blood back toward the heart.
In a way, it’s a lot like a racetrack, with blood going out one way, circling around, and coming back again. But why? Why would there be all these vessels to take blood away from the heart and then bring it back again? What do you think blood does for our body? Now would be a good time to pause the video and discuss.
Okay, you ready? Well, here’s one clue about what blood might be doing for our body. Scientists discovered that there are many small blood vessels that connect to the small intestine, which is the tube that food moves through after going through your stomach. As your food gets broken down into tiny nutrients while traveling through your stomach and small intestine, those nutrients get absorbed into your blood vessels.
This is one super important thing that blood does for our body: it carries all the nutrients from the food you’ve eaten to the different parts of your body that need those nutrients. Without blood, the nutrients in the food you eat wouldn’t be able to reach the rest of your body, where they help you grow and make repairs. But that’s not all blood does.
There’s even more. One job, especially, is so important that without it, you can’t live longer than a few minutes. Here’s a clue: scientists found out that once the blood comes back to the heart through the veins, it goes to the lungs, which are involved in breathing. As you breathe in air, your lungs take oxygen out of the air. Just like all the different parts of your body need nutrients from your food, they also need oxygen.
Take your muscles, for example. They need oxygen to be healthy and work properly. But how do they get oxygen if they’re inside your arm? The answer is blood. Blood carries both nutrients from your food and oxygen that it gets by stopping off at your lungs. Once the different parts of your body grab the oxygen from the blood, that blood goes back to the heart to get more oxygen again. Oxygen is so important that you can’t live longer than just a few minutes without it.
Now, one quick thing about the diagram I’ve been showing you. Many diagrams showing blood vessels often depict veins as looking blue. In fact, if you can see your own veins, many people describe them as looking bluish. Some have wondered if blood changes color. Is the blood carrying oxygen red while the blood low in oxygen is blue?
It’s easy to think that might be true, but scientists have found that the answer is a bit more complicated. Blood does change color slightly when it’s low on oxygen; it gets a little darker. We could say it looks more purplish-red. This partly explains why some people describe veins as looking bluish. But it’s not actually blue; it’s dark purplish-red.
That’s all for this week’s question. Thanks, Beckett, for asking it. Now for the next episode, I have three questions sent to me that I’m thinking about answering next. When this video is done playing, you’ll get to vote on one. You can choose from: Are there any flowers that bloom in the winter? Why do bears hibernate? Or, where does rain come from? So submit your vote when the video is over. I want to hear from all of you watching. There are mysteries all around us. Stay curious, and see you next week.
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