Knowledge Explorer lesson
Heart, Lungs, Bones, and Muscles
What do the heart and lungs do?
Your heart is a muscle about the size of your fist. It pumps blood all around your body. Blood carries oxygen and food to every part of you.
You have two lungs. When you breathe in, they fill with air and take in oxygen, which your body needs. When you breathe out, they let out carbon dioxide.
Your skeleton is made of bones. Bones hold your body up and protect soft parts inside: your skull protects your brain, and your ribs protect your heart and lungs. An adult has 206 bones.
Muscles move your body. Muscles attached to bones pull on them to make you walk, jump, and smile. Your heart is a special muscle that works all the time.
What you will learn
- Describe what the heart and lungs do
- Explain how bones support and protect the body
- Explain how muscles move the body
Key facts
- The heart pumps blood through the body.
- The lungs take in oxygen and let out carbon dioxide.
- People have 2 lungs.
- An adult human has 206 bones.
- The skull protects the brain. The ribs protect the heart and lungs.
- Muscles move bones by pulling on them.