Vascular resistance refers to the resistance that must be overcome to push blood through the circulatory system and create flow. The resistance offered by the peripheral circulation is known as the systemic vascular resistance (SVR) or may sometimes be referred to the antiquated term total peripheral resistance (TPR), while the resistance offered by the vasculature of the lungs is known as the pulmonary vascular resistance (PVR). Systemic vascular resistance is used in calculations of blood pressure, blood flow, and cardiac function. Vasoconstriction (i.e., decrease in blood vessel diameter) increases SVR, whereas vasodilation (increase in diameter) decreases SVR.