Blood

• Red blood cells carry oxygen
• RBC's have a large surface area for absorbing oxygen
• RBC's contain haemoglobin, a red pigment, which binds to oxygen in the lungs to become oxyhaemoglobin. In body cells the reverse happens, oxyhaemoglobin splits up to release oxygen to the cells
• White blood cells defend against infection
• Some WBC's change shape to engulf unwelcome organisms in a process called phagocytosis
• Other WBC's produce antibodies to fight microorganisms as well as antitoxins.
• RBC's do not have a nucleus
• WBC's do have a nucleus
• Platelets help the blood to clot
• Platelets are small fragments of cells with no nucleus
• Lack of platelets can cause excessive bleeding and bruising
• Plasma carries all the substances in the blood
• Plasma carrys red and white blood cells, platelets and plasma proteins
• Plasma also carrys nutrients like glucose and amino acids
• Substances carried by plasma:

  • RBC & WBC
  • Platelets
  • Nutrients like glucose and amino acids
  • CO2 from the organs to the lungs
  • Urea from the liver to the kidneys
  • Hormones
  • Proteins
  • Antiodies and antitoxins produced by WBC's