Circulatory system - Blood

• What is the job of red blood cells?


  Carry oxygen from the lungs to all the cells in the body.
• The RBC is a biconcave shape in order to store more haemoglobin which binds to the oxygen.
• The RBc does not have a nucleus to allow more room to carry oxygen.
• In the lungs, haemoglobin (red pigment) binds to oxygen forming oxyhaemoglobin.
• Some white blood cells change shape to absorb the unwelcome microorganisms. This process is called phagocytosis.
• Some WBC produce antibodies to fight microorganisms, as well as antitoxins to neutralise any toxins produced by the microorganisms.
• WBC do have a nucleus.
• Platelets are small fragments of cells which have no nucleus.
• Platelets help to clot a wound - to stop the blood pouring out and stop microorganisms getting in.
• Lack of platelets can cause excessive bleeding and bruising.
• Plasma is a pale straw-coloured liquid.
• Plasma carries the following:

  • Red and white blood cells and platelets.
  • Nutrients and glucose and amino acids.
  • $CO_2$
  • Urea from the luver to the kidneys.
  • Hormones
  • Protiens
  • Antibodies and antitoxins produced by WBC.