Arteries, veins and the circulation
The circulatory system carries blood around the body to supply the tissues with oxygen and other vital nutrients. There are three main types of blood vessel - the veins, the arteries and the tiny capillaries in between.
The arteries carry blood from the heart around the body to the capillaries, from where nutrients and oxygen flow out into the tissues. The veins then collect the blood and carry it back to the heart for replenishment and the process starts all over again.
The function of the leg veins is particularly important to our health.