Precapillary sphincters

Definition

Precapillary sphincters are rings of smooth muscle located at the entrance to capillary beds, which regulate blood flow into the capillaries. They contract or relax in response to the body's needs, controlling the blood supply to tissues and organs.

Related terms

Capillaries: Small blood vessels where the exchange of oxygen, nutrients, and waste products takes place between blood and tissues.

Vasodilation: The widening of blood vessels resulting from relaxation of smooth muscle cells within the vessel walls, particularly in large veins and arteries.

Vasoconstriction: The narrowing of blood vessels resulting from contraction of muscular wall of the vessels, primarily in small arteries and arterioles