[Science Form 3] Blood vessels and their functions

There are 3 types of blood vessels.

• Arteries
  Have a thick muscular walls to withstand high pressure.
  
  
• Veins
  The pressure in veins is usually low. Therefore, veins are wide and have thin walls with few muscles, which allow blood to flow more easily.
  
  
• Capillaries
  Capillaries, which have very thin walls, join veins and arteries. They transfer gases, food and excretory products between blood and body cell by diffusion through their thin walls.