In Comparison to a Vessel with a Large Diameter, a Vessel

Question

In comparison to a vessel with a large diameter, a vessel with a small diameter has
A) less resistance to blood flow.
B) the same amount of pressure as resistance.
C) a greater resistance to blood flow.
D) a higher blood pressure.
E) a greater blood flow.

Accepted Answer

A vessel with a small diameter has a smaller cross-sectional area, leading to a greater resistance to blood flow. According to Poiseuille's law, resistance to flow is directly proportional to the length of the vessel and the viscosity of the fluid, and inversely proportional to the fourth power of the vessel radius. This means that a smaller radius (diameter) leads to a greater resistance to blood flow.