In Which of the Following Would the Blood Flow Be

Question

In which of the following would the blood flow be highest?
A) a vessel 0.5 cm in diameter and 2 meters long
B) a vessel 1.0 cm in diameter and 10 meters long
C) a vessel 0.5 cm in diameter and 4 meters long
D) a vessel 1.0 cm in diameter and 2 meters long

Accepted Answer

Blood flow is directly proportional to the fourth power of the vessel radius. Therefore, the vessel with the larger diameter will have higher blood flow. The length of the vessel does not affect blood flow as much as the diameter, so the vessel with the shorter length is preferred. Therefore, the vessel with 1.0 cm diameter and 2 meters length will have the highest blood flow.