Lumen

Definition

In the context of blood vessels within the cardiovascular system, the lumen is the inner open space or cavity through which blood flows. It varies in diameter in different types of vessels, affecting blood flow and pressure.

Related terms

Vasoconstriction:

The narrowing of the blood vessels’ lumen due to contraction of muscular walls, which decreases blood flow and increases blood pressure.

Vasodilation:

The widening of the blood vessels’ lumen due to relaxation of muscular walls, which increases blood flow and decreases blood pressure.

Endothelium:

A thin layer of cells that lines the interior surface (lumen) of blood vessels, playing a key role in vascular functions such as controlling blood pressure and preventing clotting