If resistance vessels constrict, what happens to overall blood flow?

When resistance vessels constrict, the overall blood flow decreases. This is due to the fundamental principles of hemodynamics, where narrowing of the blood vessels increases resistance to flow. According to Poiseuille's law, blood flow is inversely proportional to resistance, implying that as resistance increases, the flow rate decreases proportionately.

In the circulatory system, resistance vessels include arterioles and small arteries, which regulate blood flow to various tissues. When these vessels constrict, they create a smaller lumen through which blood must pass, thereby elevating the resistance. As a result, the heart has to work harder to maintain blood pressure, but this often leads to a reduction in the volume of blood that can move through these constricted vessels.

Thus, when resistance vessels constrict, blood flow diminishes overall, highlighting the critical role that vessel diameter plays in regulating circulation throughout the body.