Poiseuille's law relates the flow rate with the pressure, viscosity, vessel radius and length. For the purposes of this exhibit, we will assume that the vessel in consideration is a small artery or an arteriole. Specifically, the complete circulatory system has a mean pressure drop of approximately 98 mmHg and the arterioles comprise 50% of this decrease. Using the mean velocity, blood pressure gradient can be expressed in terms of the velocity of the arteriole flow. Based on Poiseuille's law, this paper presented how the blood flow depends on the pressure and diameter of arteriole.