Circulatory system - blood

• Red Blood Cells

  • carry oxygen from the lungs to all the cells in the body
  • their shape is a biconcave disc (large surface area) absorbing O2
  • they contain a red pigment called haemoglobin
• White blood cells

  • some can change shape to gobble up unwelcomed microorganisms, by a process called phagocytosis
  • others produce antibodies to fight microorganisms as well as antitoxins to neutralise any toxins produced
  • unlike red blood cells they do have a nucleus
• Platelets

  • these are small fragmets of cells - they have no nucleus
  • they help the blood to clot at a wound - to stop blood pour out
  • lack of platelets can cause excessive bleeding and bruising
• Plasma

  Is the liquid that carries everything in blood:

  • red and white blood cells and platelets
  • nutrients like glucose and amino acids
  • carbon dioxide from the organs to the lungs
  • urea from the liver to the kidneys
  • hormones
  • proteins
  • antibodies and antitoxins