Final answer:
In the circulatory system, the length and diameter of blood vessels contribute to resistance. Longer vessels have greater resistance, while shorter vessels have lower resistance. The diameter of blood vessels can rapidly change, impacting resistance and flow.
Step-by-step explanation:
In the circulatory system, the length and diameter of blood vessels contribute to resistance. Longer vessels have greater resistance and lower flow, while shorter vessels have lower resistance and greater flow. The diameter of blood vessels, through vasodilation and vasoconstriction, can rapidly change and have a significant impact on resistance and flow. The radius of a vessel is inversely proportional to resistance, meaning that even small changes in radius can greatly affect flow.