Veins

• Veins take blood back to the heart under low pressure
• Veins have have wider lumen than arteries and have very little elastic or muscle tissue
• Veins contains valves to stop backflow of blood
• Blood flow through veins is helped by contraction of the body muscles surrounding them
• All veins carry deoxygenated blood ( because oxygen has been used up by body cells ) except for the pulmonary veins, which carry oxygenated blood from the heart to the lungs
• Veins have large lumen
• wide lumen offers less resistance to blood flow