Which term describes a decrease in the size of a blood vessel opening?

Which term describes a decrease in the size of a blood vessel opening?

• A. Vasoconstriction
• B. Vasodilation
• C. Goniometry
• D. Hypotension

Answer: (A)

Narrowing of a blood vessel opening is called vasoconstriction. This happens when the smooth muscle in the vessel wall, especially in arteries and arterioles, contracts, reducing the internal diameter (lumen). The smaller diameter increases resistance to flow, which can raise overall blood pressure and help redirect blood to tissues that need it most during stress or cold, or during blood loss to preserve perfusion to vital organs. This is different from vasodilation, which widens the vessel and lowers resistance. The other options aren’t about changing vessel size: goniometry measures joint angles, and hypotension refers to unusually low blood pressure.

Narrowing of a blood vessel opening is called vasoconstriction. This happens when the smooth muscle in the vessel wall, especially in arteries and arterioles, contracts, reducing the internal diameter (lumen). The smaller diameter increases resistance to flow, which can raise overall blood pressure and help redirect blood to tissues that need it most during stress or cold, or during blood loss to preserve perfusion to vital organs. This is different from vasodilation, which widens the vessel and lowers resistance. The other options aren’t about changing vessel size: goniometry measures joint angles, and hypotension refers to unusually low blood pressure.