Mainly to make life easier.
if one layer changes than scientists don't need to change all of their data.
it also helps keep organized.
hope this helped
ebs02
:)
Answer:
The circulatory system consists of the heart, the arteries, veins, and capillaries.
Explanation:
Efferent nerve any nerve that carries impulses from the central nervous system toward the periphery, such as a motor nerve