AAMC FL Practice Exam 2025 – The Comprehensive All-in-One Guide to Exam Success!

Poiseuille's law describes how the flow of a fluid through a cylindrical vessel is influenced by several key factors, namely the radius of the vessel, the length of the vessel, and the viscosity of the fluid. The law indicates that resistance to flow increases with longer vessel lengths and higher fluid viscosity, while resistance decreases with larger vessel radii.

In this context, the density of the fluid is not a factor that directly affects the resistance to flow as described by Poiseuille's law. Density can influence the behavior of a fluid under certain conditions, such as buoyancy and gravitational force, but it does not enter into the equation for resistance to laminar flow. Therefore, since resistance is a function of radius, length, and viscosity, the factor that does not influence resistance in this scenario is indeed the density of the fluid.

Understanding the application of Poiseuille's law helps clarify the conditions under which blood flow can be optimized or hindered, particularly in physiological or pathological states.