Red Blood Cells Say: red blud sels Red blood cells have the important job of carrying oxygen. These cells, which float in your blood, begin their journey in the lungs, where they pick up oxygen from the air you breathe. Then they travel to the heart, which pumps out the blood, delivering oxygen to all parts of your body. Back to Articles Related Articles Note: All information is for educational purposes only. For specific medical advice, diagnoses, and treatment, consult your doctor. © 1995-2021 KidsHealth®. All rights reserved. Images provided by The Nemours Foundation, iStock, Getty Images, Veer, Shutterstock, and Clipart.com.