Blood vessels form the body's essential transport network. Through the circulatory system, oxygen, nutrients and hormones are delivered to trillions of cells, while waste products are carried away. We explore how this complex network functions and why healthy blood vessels are so important. We also look at varicose veins and modern treatment options, the use of compression stockings for venous conditions, and cholesterol as a key risk factor in the development of plaque in the arteries.