# What is the human skeleton?

An episode of [Science for Kids / Science's Not Boring: The Kids Science Podcast](https://invisiblenetwork.ai/podcast/1896928296), 5 Aug 2026, 13 min.

Audio: https://www.buzzsprout.com/2624612/episodes/19568527-what-is-the-human-skeleton.mp3

Did you know you are walking around inside a self-healing superhero suit of armor? It is true! Your bones do so much more than just hold you up. In this episode of Science is Not Boring, Mira and Finn dive deep into the human skeleton to uncover its mind-blowing secrets! Discover why babies are born with around three hundred bones, but adults only have two hundred and six (hint: you didn't lose them!). We will explore the femur, a thigh bone so incredibly strong it could hold the weight of three stacked elephants, and the stapes, a tiny bone hidden in your ear the size of a single sesame seed! But wait, it gets even cooler! Your bones are actually super-busy factories pumping out over two million red blood cells every single second. Plus, find out how microscopic "bulldozers" and "builders" work together to heal broken bones, and why humans share a crazy neck secret with towering giraffes! Get ready to test your skeletal knowledge with our fun trivia quiz at the end!

## Transcript

[0:00] SPEAKER_00: Welcome to Science Is Not Boring by Kidopoly.com.
[0:04] SPEAKER_00: I'm Mira! And I'm Finn.
[0:06] SPEAKER_00: Before we dive in, we have a very special hello for a huge fan named Avon.
[0:12] SPEAKER_00: Avon is six years old, lives all the way in Washington State, and listens every single night at bedtime.
[0:19] SPEAKER_00: That is awesome!
[0:20] SPEAKER_01: Hi Avon.
[0:21] SPEAKER_01: We hear you are an absolute expert at trying to beat your mum at the quizzes.
[0:26] SPEAKER_01: Good luck today.
[0:27] SPEAKER_00: We also want to send a big hello to Avon's big sisters, Audrey and Bailey.
[0:32] SPEAKER_00: And we can't forget about your cat Jimmy.
[0:35] SPEAKER_01: Avon actually sent in an amazing request.
[0:38] SPEAKER_01: He asked us all about bones.
[0:41] SPEAKER_01: Why do we have them?
[0:42] SPEAKER_01: How do they grow?
[0:43] SPEAKER_01: And what are they even made of?
[0:45] SPEAKER_00: It is the perfect topic.
[0:48] SPEAKER_00: Inside you is a whole framework of more than 200 bones that hold you up.
[0:53] SPEAKER_00: But did you know your bones are basically a superpower?
[0:57] SPEAKER_00: Wait, what?
[0:58] SPEAKER_00: Superpowers?
[1:00] SPEAKER_00: Are they unbreakable?
[1:01] SPEAKER_00: Almost.
[1:02] SPEAKER_00: There is a bone in your body that is literally four times stronger than concrete.
[1:07] SPEAKER_01: No way.
[1:08] SPEAKER_01: Stronger than concrete!
[1:10] SPEAKER_00: Yep, and they aren't just dry dusty sticks.
[1:13] SPEAKER_00: Your bones are super busy, living factories.
[1:16] SPEAKER_00: Right now, they are pumping out more than 2.4 million new red blood cells every single second.
[1:23] SPEAKER_01: 2.4 million a second?
[1:26] SPEAKER_01: That means millions of cells just got made while I said that sentence.
[1:31] SPEAKER_01: Let's get to the bones of the matter.
[1:33] SPEAKER_00: To start, think of your skeleton like the heavy wooden frame of a house, or the steel beams inside a tall skyscraper.
[1:40] SPEAKER_00: Without it, you wouldn't be able to stand up, walk, or move at all.
[1:47] SPEAKER_01: I'd just be a giant squishy puddle of thin jelly on the floor.
[1:52] SPEAKER_00: Exactly! You would be a land jellyfish.
[1:55] SPEAKER_00: But bones do more than just hold you up.
[1:58] SPEAKER_00: They form protective cages to keep your soft inside safe.
[2:02] SPEAKER_01: Oh, like how my skull is basically a built-in helmet for my brain.
[2:07] SPEAKER_00: Exactly! And your ribs are a flexible cage protecting your heart and lungs.
[2:12] SPEAKER_00: Your bones are the ultimate body armour.
[2:15] SPEAKER_01: Okay, so they are my armour and my frame.
[2:18] SPEAKER_01: How many bones do I actually have in my armour?
[2:21] SPEAKER_00: Well, as a grown-up, a human has exactly 206 bones.
[2:26] SPEAKER_00: But Finn, when you were a baby, you had around 300.
[2:30] SPEAKER_01: Wait, what?
[2:32] SPEAKER_01: Hold on.
[2:33] SPEAKER_01: Did I lose almost a hundred bones somewhere?
[2:35] SPEAKER_01: Did they fall out?
[2:37] SPEAKER_00: Nope, you didn't lose them.
[2:39] SPEAKER_00: When babies are born, lots of their skeleton isn't hard bone yet.
[2:43] SPEAKER_00: It's made of a flexible rubbery tissue called cartilage.
[2:47] SPEAKER_01: Wait, isn't that the squishy stuff in my ears and the tip of my nose?
[2:52] SPEAKER_00: That's exactly what it is.
[2:54] SPEAKER_00: Having a flexible skeleton helps babies bend and squeeze safely when they are growing.
[2:59] SPEAKER_00: But as you get older, an amazing biological process called ossification takes place.
[3:05] SPEAKER_00: Ossification?
[3:07] SPEAKER_00: That sounds like a wizard's magic spell.
[3:09] SPEAKER_00: It kind of is.
[3:11] SPEAKER_00: Over the years, that soft cartilage absorbs minerals and hardens into solid bone.
[3:16] SPEAKER_00: And as it hardens, many of those smaller baby bones actually fuse or melt together into larger single bones.
[3:25] SPEAKER_01: Oh, so a bunch of my little baby bones click together like Lego bricks to make bigger kid bones.
[3:31] SPEAKER_01: That is brilliant.
[3:32] SPEAKER_00: It gets even wilder when you look at how strong those grown-up bones are.
[3:37] SPEAKER_00: Let's talk about the biggest, strongest bone in your entire body.
[3:42] SPEAKER_00: Which one is it?
[3:43] SPEAKER_00: My skull.
[3:45] SPEAKER_00: Nope.
[3:46] SPEAKER_00: It's called the femur, which is your thigh bone in your leg.
[3:50] SPEAKER_00: It carries all your weight when you walk and run.
[3:53] SPEAKER_01: How strong is it?
[3:54] SPEAKER_01: Really?
[3:55] SPEAKER_01: Like lifting a car strong?
[3:57] SPEAKER_00: Actually, yes.
[3:59] SPEAKER_00: Scientists have tested this.
[4:01] SPEAKER_00: Just one cubic inch of human bone can withstand a crushing load of up to 19,000 pounds.
[4:10] SPEAKER_00: 19,000 pounds?
[4:12] SPEAKER_00: What does that even look like?
[4:14] SPEAKER_00: Imagine taking three adult elephants, stacking them on top of each other, and balancing them all on a piece of bone the size of a small matchbox.
[4:24] SPEAKER_00: The bone wouldn't even be crushed.
[4:27] SPEAKER_01: That is unbelievable.
[4:29] SPEAKER_01: It really is stronger than a block of concrete.
[4:32] SPEAKER_01: But wait, if my leg bone is that strong, why doesn't my leg feel like a heavy concrete pillar?
[4:39] SPEAKER_00: Because bones have a genius chemical recipe.
[4:42] SPEAKER_00: They are composite materials, meaning they mix two different things together.
[4:47] SPEAKER_00: They are made of a stretchy protein called collagen, mixed with a super hard mineral called calcium.
[4:54] SPEAKER_01: So it's kind of like how construction workers put flexible steel bars inside hard concrete when they build tall towers.
[5:00] SPEAKER_00: You nailed it! The calcium makes the bone hard enough to hold your weight, but the collagen makes it just flexible enough that it can bend slightly without snapping when you jump.
[5:12] SPEAKER_01: Wow.
[5:12] SPEAKER_01: Nature basically invented reinforced concrete before humans did.
[5:17] SPEAKER_01: Literally.
[5:18] SPEAKER_00: In fact, researchers at Princeton University recently created a brand new type of building material, inspired directly by the microscopic structures inside the human femur.
[5:29] SPEAKER_00: Did it work?
[5:30] SPEAKER_01: Was it strong?
[5:32] SPEAKER_00: It was amazing! Their bone-inspired concrete was over five times stronger than regular concrete.
[5:39] SPEAKER_01: That is so cool.
[5:41] SPEAKER_01: Human bones are literally teaching scientists how to build better cities.
[5:45] SPEAKER_00: Now, if the femur is the absolute biggest bone, what do you think the smallest bone is?
[5:51] SPEAKER_01: Hmm.
[5:53] SPEAKER_01: I'm guessing it's one of my pinky toes?
[5:55] SPEAKER_01: Or maybe a tiny bone inside my wrist?
[5:59] SPEAKER_00: Nope, it's nowhere near your hands or feet.
[6:02] SPEAKER_00: The smallest bone is hidden deep inside your head.
[6:06] SPEAKER_00: It's in your middle ear, and it's called the stapes, or the stirrup bone.
[6:12] SPEAKER_01: Wait, how small are we talking?
[6:15] SPEAKER_01: Like the size of an apple seed?
[6:17] SPEAKER_00: Way smaller.
[6:18] SPEAKER_00: The stapes is only about 2.5 to 3 millimeters long.
[6:24] SPEAKER_00: That is the exact size of a sesame seed.
[6:27] SPEAKER_01: A sesame seed?
[6:29] SPEAKER_01: What is a bone that tiny even do in there?
[6:32] SPEAKER_00: It is absolutely critical for your hearing.
[6:35] SPEAKER_00: When sound waves enter your ear, they bounce off your eardrum, which moves three tiny bones.
[6:42] SPEAKER_00: The stapes acts like a tiny piston, sending those sound vibrations deep into your inner ear.
[6:49] SPEAKER_01: So without a bone the size of a sesame seed, I wouldn't be able to hear music or you talking right now.
[6:55] SPEAKER_01: That is wild.
[6:56] SPEAKER_00: It is.
[6:57] SPEAKER_00: And while the stapes is busy vibrating, the big bones in your body are busy manufacturing.
[7:04] SPEAKER_00: Because bones aren't just solid rock, they are hollow inside.
[7:08] SPEAKER_00: Hollow?
[7:09] SPEAKER_00: Like a pipe?
[7:11] SPEAKER_00: What's inside them?
[7:12] SPEAKER_00: Inside the hard outer shell of your larger bones is a squishy jelly-like centre called bone marrow.
[7:19] SPEAKER_00: And this marrow is an incredibly busy factory.
[7:23] SPEAKER_01: Oh wait! Is that the factory that makes 2.4 million blood cells every second?
[7:28] SPEAKER_00: Exactly! Your red bone marrow creates red blood cells to carry oxygen.
[7:34] SPEAKER_00: It also creates white blood cells, which fight off infections and viruses to keep you healthy.
[7:40] SPEAKER_01: 2.4 million a second.
[7:43] SPEAKER_01: That means while we've been talking for just five minutes, my bones have manufactured over 700 million new blood cells.
[7:51] SPEAKER_00: Your math is spot on! These red blood cells act like a fleet of microscopic delivery trucks, rushing oxygen from your lungs to every single muscle and organ in your body.
[8:04] SPEAKER_01: Okay, so my skeleton is an armour, a frame, a sound amplifier, and a blood factory.
[8:11] SPEAKER_01: But what happens if a bone breaks?
[8:13] SPEAKER_00: Can it fix itself?
[8:14] SPEAKER_00: It sure can! The moment a bone breaks, your body sounds an alarm.
[8:19] SPEAKER_00: It rushes blood to the crack to form a protective clot.
[8:23] SPEAKER_00: Then, a cleanup crew of cells called osteoclasts arrive to clear away any sharp broken edges.
[8:30] unknown: Haha!
[8:31] SPEAKER_01: Osteoclasts! They sound like little microscopic bulldozers.
[8:36] SPEAKER_01: What happens next?
[8:37] SPEAKER_00: After the bulldozers finish, the builders arrive.
[8:41] SPEAKER_00: Special cells called osteoblasts start laying down fresh collagen and minerals.
[8:46] SPEAKER_00: They literally build a bridge of new solid bone across the brake.
[8:51] SPEAKER_01: That is basically a self-healing superpower suit.
[8:54] SPEAKER_01: Are human bones the coolest in the whole animal kingdom?
[8:58] SPEAKER_00: They are pretty amazing, but animal bones have wild secrets too.
[9:02] SPEAKER_00: Here is one of my favourite weird facts.
[9:05] SPEAKER_00: Did you know that humans and giraffes have the exact same number of bones in their necks?
[9:11] SPEAKER_00: No way! A giraffe's neck can be over six feet long.
[9:15] SPEAKER_00: How is that possible?
[9:17] SPEAKER_00: It is totally true.
[9:19] SPEAKER_00: We both have exactly seven neck bones.
[9:22] SPEAKER_00: The only difference is that a giraffe's seven bones are just massively stretched out, with each one measuring about ten inches long.
[9:30] SPEAKER_00: Alright Finn, it is quiz time! Let's see if Avon can beat you to the answers from his bed in Washington.
[9:37] SPEAKER_01: Oh man, the pressure is on! Okay, Avon, let's do this.
[9:42] SPEAKER_00: First question.
[9:44] SPEAKER_00: How many bones does a human baby have when they are first born?
[9:51] SPEAKER_00: Next one.
[9:53] SPEAKER_00: What is the scientific name of the biggest and strongest bone in the human body?
[10:02] SPEAKER_00: Question three.
[10:03] SPEAKER_00: Where exactly in your body is the smallest bone called the stapes located?
[10:12] SPEAKER_00: Here's number four.
[10:14] SPEAKER_00: What is the name of the squishy stuff inside your bones that produces millions of red blood cells?
[10:24] SPEAKER_00: Last question.
[10:26] SPEAKER_00: How many neck bones do humans and giraffes both have?
[10:33] SPEAKER_00: Great job! Let's see how you did and go through the answers.
[10:38] SPEAKER_00: The first answer is, a baby is born with around 300 bones, which later fuse together.
[10:45] SPEAKER_00: For question two, the strongest and longest bone is the femur, also known as the thigh bone.
[10:52] SPEAKER_00: Number three, the answer is the tiny stapes bone is located hidden deep inside your middle ear.
[11:00] SPEAKER_00: Question 4.
[11:02] SPEAKER_00: The squishy factory that makes your blood is called bone marrow.
[11:06] SPEAKER_00: And the final answer is both humans and giraffes have exactly seven neck bones.
[11:13] SPEAKER_01: I am seriously never going to look at my skeleton the same way again.
[11:17] SPEAKER_01: I'm practically walking around inside a self-healing, blood-making superhero suit.
[11:23] SPEAKER_00: It really is spectacular.
[11:25] SPEAKER_00: I hope you had fun learning all about bones, Avon, and that you totally crushed the quiz against your mun tonight.
[11:31] SPEAKER_01: Hey everyone, if you love discovering wild, mind-blowing science facts with us, please leave our show a five-star review.
[11:39] SPEAKER_00: Yes, leave a review and tell us which bone fact blew your mind the most.
[11:44] SPEAKER_00: Was it the tiny earbone or the super strong femur?
[11:48] SPEAKER_00: Just scroll down on your podcast app and tap the five stars.
[11:51] SPEAKER_01: Oh, and don't forget to head over to our site kidopoly.com.
[11:55] SPEAKER_01: We've got tons of fun learning games, activities, and awesome resources there to keep exploring.
[12:01] SPEAKER_00: And if you want to shout out on the show, just like Avon, or want to send us some feedback, send us an email at hello at kidopoly.com.
[12:09] SPEAKER_00: We would love to hear from you.
[12:11] SPEAKER_01: Thanks for listening, and see you next time on Science is Not Boring.
[12:15] SPEAKER_01: Bye everyone, keep exploring.

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