blood vessels

• arteries

  • carry oxygenated blood away from the heart
  • they have thick elastic and muscular walls
  • they have small passageways for blood
  • contain blood under high pressure
• veins

  • carry deoxygenated blood to the heart
  • have thin, less muscular walls
  • have larger passageways for blood
  • contain blood under low pressure
  • have valves to prevent back flow of blood