Rocket races through the lab with a paper heart. "The heart does everything!" he shouts.
Raven holds up the paper lungs. "What do you notice? Can the heart work alone?"
Rocket stops. "Hmm. Blood needs oxygen from somewhere."
Nova hovers between the paper organs. "Follow the oxygen," she says. "Which organs pass it along?"
A system is a group of organs that work together on a big job.
Scientists list ten major systems in the human body.
Here are six we will meet in Body Lab.
| System | Some parts | Big job |
|---|---|---|
| skeletal | bones | Gives shape, support and protection |
| muscular | muscles | Moves the body |
| nervous | brain, spinal cord, nerves | Sends and controls messages |
| circulatory | heart, blood vessels | Carries blood around the body |
| respiratory | lungs, windpipe | Brings in oxygen, sends out carbon dioxide |
| digestive | stomach, intestines | Breaks down food |
No system works alone. They pass jobs along like a team.
The lungs bring oxygen into the blood.
The heart pumps that blood through the body.
Then oxygen moves from the blood into the cells.
The brain sends messages that tell muscles when to move.
| Statement | True or false? |
|---|---|
| The heart and blood vessels work as a system. | ? |
| Each system works all alone. | ? |
| The brain sends messages to muscles. | ? |
| Bones belong to the digestive system. | ? |
Super system spotting! Tomorrow we put every level together and make a claim like real scientists.