Explain the statement servicing the capillaries is the essential function of the organs of the circulatory system?

The capillaries are where the actual transfer of oxygen to the cells happen making it the absolute essential part of the system. The lungs/gills/skin whole job is to get oxygen into the bloodstream so that the capillaries have oxygen to transfer to the cells. The hearts whole job is to supply enough pressure to circulate the blood past the capillaries so it constantly has new oxygenated blood to transfer oxygen to the cells.

--Ryan F