Final answer:
Perfusion pressure is the localized pressure gradient needed for good blood flow.
Step-by-step explanation:
The localized pressure gradient needed to maintain good blood flow is called perfusion pressure. Perfusion pressure is the difference between the arterial pressure and the pressure in the veins, and it is responsible for driving blood through the capillaries and delivering oxygen and nutrients to the tissues. It is an important factor in maintaining proper blood flow and ensuring the optimal functioning of organs and tissues.