Human Circulatory System
Primary 6 · Science and Elementary Technology
Human Circulatory System
Lesson 1 of 6
25 min
Let's begin
At break time, Byiringiro sprints from one end of the football pitch to the other. When he stops, he puts his hand on his chest: thump-thump-thump-thump, much faster than in class. "What is my heart doing?" he asks. "And why is it going so fast now?"
His heart is the pump of a system that reaches every part of his body. Today you will find out what this system is made of and what it does.
To circulate means to move around and come back. The circulatory system moves blood around the body, all the time, from before you are born until the end of your life.
| Part | What it is | Its job |
|---|---|---|
| Heart | A strong muscle in the middle of your chest | Pumps blood around the body |
| Blood vessels | Tubes: arteries, veins and capillaries | Carry blood to and from every part of the body |
| Blood | A red liquid made of plasma and cells | Carries substances around the body |
The lungs work very closely with the circulatory system: that is where the blood picks up oxygen and gets rid of carbon dioxide.
Blood always stays inside the heart and blood vessels, so we call it a closed system. Think of Kigali's roads: trucks travel along them to deliver food to every shop and house, and collect the rubbish. The heart is like the engine that keeps the trucks moving, the blood vessels are the roads, and the blood is the trucks with their loads.
Your heart beats about 100,000 times a day. When Byiringiro runs, his muscles need more oxygen and food, so his heart beats faster to deliver them.
Tip
H-V-B: the Heart pumps, the Vessels are the roads, and the Blood carries the load.
Answers
What you learned today
Sources and credits
The exercises (Try it yourself and the practice questions) are written by Ganzaa.
Quick check
The circulatory system is like Kigali's roads and trucks. Match each part to what it is like.
Tap one on the left, then its partner on the right.
