Blood

• Blood is a tissue consisting of plasma, in which the red blood cells, white blood cells and platelets are suspended
• Plasma


  Carries glucose/amino acids, hormones, proteins, antibodies/antitoxins

  • yellow liquid
  • transport blood cells and other substances
  • waste CO2 is transported to lungs
  • Urea formed in the liver is carried to the kidneys where it is removed from your blood to form urine
• Red blood cells


  pick up oxygen from the air in the lungs and carry it to your cells where it is needed

  • no nucleus - more room for haemoglobin
  • packed with red pigment that binds to oxygen
  • bi-concave discs - increase surface area:volume for diffusion
• White blood cells


  form part of the body's immune system against harmful microorganisms

  • have a nucleus
  • lymphocytes - form antibodies against microorganisms and form antitoxins to neutralise toxins
  • phagocytes - engulf and digest invading bacteria and viruses
• Platelets


  protect the body by stopping/reducing bleeding and stopping microorganisms from entering

  • tiny fragment of cells (no nucleus)
  • clump together to help form clots
  • lack of platelets can cause excessive bleeding and bruising