Rocket draws a heart as one big empty space. "Blood goes in, blood goes out. Done!"
Raven tilts her head. "What do you notice about the real heart picture in our book?"
Rocket looks again. There are lines inside, like walls between rooms.
Nova blinks a soft light. "Count the rooms," she says. "Then look for doors between them."
"Oops," Rocket laughs. "My drawing needs a remodel!"
Your heart has four spaces inside. Each one is called a chamber.
There are two chambers on each side of the heart.
The two top chambers are the atria. Say it like this: AY-tree-uh.
The two bottom chambers are the ventricles. Say it like this: VEN-trih-kulz.
A thick wall of muscle, the septum, splits the left side from the right side.
| Chamber | Where it is | Its job |
|---|---|---|
| Atrium (one of the atria) | On top | Fills with blood coming back to the heart |
| Ventricle | On the bottom | Squeezes to pump blood out of the heart |
The heart has four valves. A valve works like a one-way door.
It opens to let blood move ahead. Then it shuts so blood cannot flow backward.
When valves shut, they make a sound: lub-dub, lub-dub.
Your heart is like two pumps side by side.
The right side gets blood from the body. It pumps that blood to the lungs.
In the lungs, blood picks up fresh oxygen.
The left side gets that blood from the lungs. It pumps it out to the whole body.
| Statement | True or false? |
|---|---|
| The septum is a wall between the left and right sides. | ? |
| The ventricles are the top chambers. | ? |
| The left side pumps blood out to the body. | ? |
| The lub-dub sound comes from valves shutting. | ? |
Wonderful work! Mistakes like Rocket's help us learn. Tomorrow we follow blood along its roads.