Final answer:
Blood flow through vessels is directly related to the pressure difference between the two ends of the vessel. As arteries become smaller, blood flow encounters more resistance due to friction against the arterial walls, resulting in a decrease in blood pressure. The pressure difference in the circulatory system is created by the pumping force of the heart and is regulated by varying vessel diameters.
Step-by-step explanation:
Blood flow through vessels is directly related to the pressure difference between the two ends of the vessel. As arteries become smaller, blood flow encounters more resistance due to friction against the arterial walls, resulting in a decrease in blood pressure. This reduction in pressure ensures that capillaries, the tiniest vessels, can withstand the blood flow without bursting. The pressure difference in the circulatory system is created by the pumping force of the heart and is regulated by varying vessel diameters.