blood

• what are the components of blood?

  1. plasma - transports blood cells and other substances around the body
  2. red blood cells - pick up o2 from the lungs and carry it to cells
  3. white blood cells - form part of the body's defence system
  4. platelets - cell fragments that start the clotting process at wound sites
• what does blood plasma do as a transport medium?


  1. waste carbon dioxide produced by cells is carried to the lungs
  2. urea is formed in the liver from breakdown of excess proteins is carried to kidneys when its removed from the blood to urine
  3. small soluble products of digestion pass into plasma from small intestines and are transported to the individual cells
• how are red blood cells adapted?


  1. biconcave discs - increased SA to volume ratio for diffusion
  2. have haemoglobin that binds to oxygen
  3. no nucleus - space for haemoglobin
• what is the difference between lymphocytes and phagocytes?


  Lymphocytes: Adaptive immune cells that produce antibodies and target specific pathogens. Phagocytes: Innate immune cells that engulf and digest pathogens.
• white blood cells


  • some can change shape to engulf unwelcome microorganisms in a process called phagocytosis
  • others produce antibodies to fight microorganisms as well as antitoxins to neutralise toxins produced by microorganisms
  • have a nucleus
• platelets


  • small fragments of cells with no nucleus
  • help blood to clot at a wound
  • lack of platelets causes excessive bleeding and bruising
• plasma is a liquid that carries:

  • red and white blood cells
  • glucose and amino acids to taste to the cells of the body
  • carbon dioxide
  • urea
  • hormones
  • proteins
  • antibodies and antitoxins