Red blood cells are designed to pick up oxygen in the lungs and transport it throughout the body via the circulatory system. |
![](https://webarchive.library.unt.edu/eot2008/20081105222558im_/http://www.nlm.nih.gov/exhibition/changingthefaceofmedicine/img/spacer.gif) |
Their donut-like shape and water-balloon-like flexibility allows them to pass through even the tiniest blood vessels.
View the text-only version |