Your Amazing Body: Bones, Heart, and Lungs

Put your hand on the left side of your chest and stay very still. Do you feel a soft thump-thump? That is your heart, and it beats about 100 times every single minute when you are little. That is more than 100,000 thumps a day, and it never takes a break, not even when you sleep! Your body has many busy parts that all work together to keep you running, jumping, and giggling. Today we will meet three of the biggest helpers: your bones, your heart, and your lungs.

By the end of this lesson you will be able to: 1. Say what your bones do for your body. 2. Tell what your heart does. 3. Show how your lungs help you breathe.

Bones are hard and strong. They hold you up so you do not flop like a jellyfish! Your bones give your body its shape and let you stand tall. You have 206 bones, and the longest one is in your leg. Bones also work like a helmet: your skull is a bone that keeps your soft brain safe inside. Wiggle your fingers and feel all the tiny bones moving there!

Your heart is about the size of your own fist. Make a fist and look at it, that is how big your heart is right now. The heart is a pump. Squeeze, squeeze, squeeze! It pushes red blood all around your body to bring food and oxygen to every part. When you run fast, your heart beats quicker to send blood faster. That is why your chest goes thump-thump-thump after you play hard.

You have two lungs, one on each side of your chest. They are soft and squishy, like two balloons. When you breathe in, your lungs fill up with air and grow bigger. When you breathe out, they let the air go and get smaller. Your lungs grab the good part of the air (called oxygen) and give it to your blood. Take a big, slow breath right now and feel your chest get bigger. That is your lungs at work!