Arteries veins Capillaries

• Arteries

  Arteries carry blood away from the heart; blood is pumped through arteries at high pressure; arteries have an outer layer of connective tissue containing elastic fibres; a thick middle layer containing elastic fibres; relatively narrow lumen; elastic walls of the arteries stretch and recoil to accommodate the surge of blood pressure after each contraction of the heart
• Veins

  Veins carry blood towards the heart; veins have an outer layer of connective tissue containing elastic fibres; thinner muscular wall than arteries; the lumen of a vein is wider than that of an artery; valves are present in veins to prevent backflow of blood; valves needed as the blood is flowing back to the heart at low pressure
• Capillaries

  Capillaries are only one cell thick; allows quick/efficient exchange of materials/substances with tissues