How Vessel Size Changes Blood Flow

Vascular resistance explains how vessel size, blood thickness, and vessel length affect blood flow and blood pressure. It describes the force blood faces as it moves through blood vessels. This force also helps determine how hard the heart must work to keep blood moving.

Vessel diameter has the b...

When blood flows through the vessels, the friction between the vessel walls and blood creates a resistive force called peripheral or vascular resistance.

This resistance is affected by three main factors.

The first factor is blood viscosity or its thickness. It remains constant except in conditions like polycythemia, where an abnor...