The Blood Highways
Arteries, veins and the muscle pump
Your muscles need fuel and oxygen for every step, sprint and jump. Delivering it is a vast highway system â arteries, veins and capillaries â that would circle the Earth if laid end to end!
Arteries and veins feeding a muscle
Real anatomy picture coming soon
Real anatomy photo spot: red arteries and blue veins branching through muscle
Out and back
Arteries are the outbound highways â they carry oxygen-rich blood from your heart out to your muscles. Veins are the return roads â they carry the used blood back. In between are the capillaries: highways so thin that blood cells squeeze through one at a time, dropping off oxygen and food while collecting carbon dioxide and waste.
The muscle pump
Here's the clever bit: veins have one-way valves, like little doors that only swing one way. When your muscles squeeze the veins as you walk, they squash the blood upward â your muscles literally help pump blood back to your heart! That's why walking keeps your legs healthy and sitting still for hours makes them feel heavy.
Mr. Bones says: I'm a fictional skeleton, not a doctor! This is for learning and fun. If anything hurts, stop and tell a grown-up you trust.
