5. Flow versus velocity and total cross-sectional area

As a vascular tree branches, the total cross-sectional area changes. The total cross-sectional area is _ in the aorta and vena cava, _ across all capillaries combined, and then _ again as vessels merge on the venous side.

small, much larger, becomes smaller

Flow rate through the overall circulation is _, expect for _.

continuous, temporary storage

Velocity is fastest where _, and slowest where _.

the total cross-sectional area is smallest, the total cross-sectional area is greatest

Slow capillary velocity provides time for _.

exchange and helps protect fragile capillary walls

The slow velocity is a consequence of the _.

large total area of many capillaries, not the small diameter of one capillary considered in

isolation