Vasodilation results in what?

• A. A widening of the diameter of a blood vessel, which reduces blood pressure.
• B. A narrowing of a blood vessel.
• C. An Increase In Blood Viscosity.
• D. A Change In Heart Rate.

Answer: (A)

Vasodilation is the widening of a blood vessel due to relaxation of the smooth muscle in its walls. This increase in diameter lowers vascular resistance, allowing blood to flow more easily. Because flow changes with the radius to a high power, vasodilation can significantly increase blood flow to tissues. If cardiac output stays the same, this reduced resistance tends to lower arterial blood pressure. The other ideas aren’t direct results of vasodilation: narrowing would be vasoconstriction; blood viscosity is a property of the blood itself and doesn’t change with vessel diameter; heart rate is influenced by multiple factors and isn’t a direct consequence of vasodilation.