Blood vessels are hollow tubes in your body that carry blood to and from your heart. They help deliver important things like oxygen and nutrients to all your body parts, and they also carry away waste like carbon dioxide.
There are three main kinds:
Arteries: These carry oxygen-rich blood away from your heart to the rest of your body. They have thick walls to handle strong blood flow.
Veins: These bring oxygen-poor blood back to your heart. They have valves that stop blood from flowing backward.
Capillaries: The smallest vessels that connect arteries and veins. They allow oxygen and nutrients to move from blood into your body’s cells and waste to move back into the blood.
Together, these vessels form a huge network — if stretched out, they would wrap around the Earth multiple times! This network keeps your body working by constantly moving blood where it’s needed.