Vascular resistance refers to the opposition that blood vessels offer to the flow of blood. It is primarily determined by the diameter of the blood vessels; narrower vessels create more resistance, while wider vessels allow for easier blood flow. This resistance is crucial for regulating blood pressure and ensuring that blood reaches various tissues throughout the body. Factors such as blood vessel elasticity, blood viscosity, and overall vessel length also influence vascular resistance. When resistance increases, the heart must work harder to pump blood, which can lead to conditions like hypertension. Understanding vascular resistance is essential for maintaining cardiovascular health.