types of blood vessels

• Arteries


  Carry blood away from the heart
• Arteries


  • Carry blood under pressure
  • Have strong and elastic walls
  • Have thick walls compared to the size of the lumen
  • Contain thick layers to make them strong
• Aorta


  The largest artery in the body
• Veins


  Take blood back to the heart
• Veins


  • Have a bigger lumen than arteries to help the blood flow despite the lower pressure
  • Have valves to keep the blood flowing in the right direction
• Vena cava


  The largest vein in the body
• Arteries to capillaries to veins

  1. Arteries branch into capillaries

  2. Capillaries join into veins
• Capillaries


  • Are very tiny, too small to see
  • Carry blood very close to every cell in the body to exchange substances with them
  • Have permeable walls so substances can diffuse in and out
  • Supply food and oxygen and take away waste like CO2
  • Have walls that are usually one cell thick which increases the rate of diffusion by decreasing the distance over which it happens