Vasoconstriction - GCSE Biology Definition

Vasoconstriction is a process where blood vessels become narrower. This happens when the muscles in the walls of the blood vessels tighten, making the lumen (the space inside the vessel) smaller. This process helps to direct blood flow to where it is most needed in the body and helps to increase blood pressure. It is an important response when the body needs to conserve heat in cold weather, as less blood flows to the surface of the skin, helping to keep warmth inside the body. Vasoconstriction is controlled by the nervous system and is one way the body maintains a stable internal environment, known as homeostasis.