MICROANATOMY

Detailed explanation-1: -Vasoconstriction reduces the volume or space inside affected blood vessels. When blood vessel volume is lowered, blood flow is also reduced. At the same time, the resistance or force of blood flow is raised. This causes higher blood pressure.

Detailed explanation-2: -Reflex venoconstriction is defined as a neurogenically induced contraction of the smooth muscle in the walls of veins; it causes a reduction in vascular capacity which is seen as a decrease in the volume of blood contained at the same pressure, an increase in the pressure at the same volume, or a combination of both.

Detailed explanation-3: -Venous Resistance. Constriction of the veins decreases their capacity and expels blood from them into the systemic circulation.

Detailed explanation-4: -Now, the amount of blood flow from one end of a blood vessel to another is affected by the blood pressure, and by the resistance, which comes from the vessels themselves. Vasoconstriction, where the vessels constrict, decreases blood flow, and vasodilation, where the blood vessels expand, increases blood flow.