WHAT’S THE DIFFERENCE ...

. . . between a vein and a valve?

VEINS are vessels in the body that transport blood, without oxygen and nutrients, back to the heart.

Valves are tubes of tissue inside the veins, which control the direction of blood flow, via flap-like structures within them.

They ensure the blood keeps flowing back from distant parts of the body, such as the legs or arms, to the heart.

Different veins, in different parts of the body, vary in the number of valves within them. For instance, the veins in the thigh – femoral veins – contain between one and six valves, whereas veins in the knee, or popliteal area, can, in some people, have no valves at all.