Vein
Any one of a series of blood vessels of the vascular system that carries blood from various parts of the body back to the heart, returning oxygen-poor blood to the heart.
Anatomy
Vascular
Pertains to the blood vessels.
Valve
A structure in a blood vessel or the heart which ensures blood flows only one way. They are constructed of single or multiple flaps which swing open to allow blood to flow forwards and swing shut to prevent back flow. The valve flaps are referred to as ‘leaflets’ or ‘cusps’.