According to Poiseuille's Law, which factor has the greatest influence on resistance to blood flow?

Poiseuille's Law describes the flow of fluid through a cylindrical vessel and highlights several factors that contribute to resistance in blood flow. Among these factors, vessel diameter plays a critical role in influencing resistance.

The law states that resistance to flow is inversely proportional to the fourth power of the radius (or diameter) of the vessel. This means that even a small change in the diameter of a vessel can lead to a significant change in resistance. For instance, if the diameter of a blood vessel were to double, resistance would decrease by a factor of 16, significantly enhancing blood flow. This heightened sensitivity highlights why vessel diameter is considered the most powerful influencer of blood flow resistance.

While other factors such as vessel length and blood viscosity do affect flow and resistance, their influence is not as pronounced as that of vessel diameter. Vessel length has a linear relationship with resistance, meaning that if the length increases, resistance increases proportionally, but not as dramatically as changes in diameter. Blood viscosity also contributes to resistance, but variations in viscosity typically do not produce as significant an effect as diameter adjustments. Fluid temperature can affect viscosity but isn't a direct factor in determining resistance according to Poiseuille's Law.

Thus, vessel diameter is the primary factor that has the greatest impact