a: Circulatory system ~
b: delivery service
What: " The circulatory system is like a delivery service. It picks up stuff and drops off stuff. It does that by traveling all over the body, to reach most cells... as long as it comes close enough to every cell to pick up and drop off stuff by diffusion, it has done its job. There are different types of circulatory systems that animals use-- but all take care of distributing nutrients and picking up wastes. "
Writer: Dawn A. Tamarkin, Ph.D.
Date: Jun 11 2014 5:38 PM
# 5814 Critique Analogy