Blood vessels

• Blood vessels


  • Arteries
  • Capillaries
  • Veins
• Arteries


  Move away from the heart
• Veins


  Move to the heart
• Capillaries


  • Involved in exchanging material at the tissues
  • Wall one cell thick to allow diffusion of substances to happen easily (increase rate of diffusion)
  • Very small
  • Carry the blood really close to every cell to exchange substances
  • Permeable walls
  • Supply food and oxygen and take away waste like carbon dioxide
• Veins


  • Have valves to prevent the backflow of blood
  • Large lumen to help blood flow
  • Low pressure so walls are not thick
• Arteries


  • Have thick, strong and elastic artery walls to prevent them from breaking under high pressure of the blood
  • Thick layers of muscle make it strong
  • Elastic fibres allow it to spring back
• Blood flow


  1. Arteries branch into capillaries

  2. Capillaries join up to form veins