Dear Dr. Universe,

Why do we have blood? Where does it come from?

Norelle, Olympia

Dear Norelle,

Our bodies have many living parts, like skin, muscle, brain and bones. Blood helps keep these parts alive and healthy. The system that moves our blood around the body is sort of like a city’s postal service, my friend Astrid Suchy-Dicey said.

Suchy-Dicey is a scientist at Washington State University who is really curious about blood. Her research helps people at risk for diseases.

She said it first helps to know that blood is actually made up of different thing...