blood

• Blood


  • Transports materials around the body
  • Distributes heat around the body
  • Helps to protect against disease
• Plasma


  A liquid that cells and cell fragments are suspended in
• Plasma is a straw-coloured liquid that makes up just over half the volume of blood
• Types of blood cell and cell fragments

  • Red blood cells
  • White blood cells
  • Platelets
• Red blood cells


  • Transport the oxygen required for aerobic respiration in body cells
  • Absorb oxygen in the lungs
  • Pass through narrow blood capillaries
  • Release oxygen to respiring cells
• Adaptations of red blood cells

  • Enable them to carry a maximum amount of oxygen
  • They contain the protein haemoglobin, which gives them their red colour
• Haemoglobin


  Can combine reversibly with oxygen
• Haemoglobin combining reversibly with oxygen


  Important - it means that it can combine with oxygen as blood passes through the lungs, and release the oxygen when it reaches the cells
• Red blood cells


  • They have no nucleus - they lose it during their development - so they can pack in more haemoglobin
  • They are small and flexible so that they can fit through narrow blood capillaries
  • They have a biconcave shape - they are the shape of a disc that is curved inwards on both sides - to maximise their surface area for oxygen absorption
  • They are thin, so there is only a short distance for the oxygen to diffuse to reach the centre of the cell
• what is the function of plasma in the blood?


  transporting carbon dioxide, digested food molecules, urea & hormones; distributing heat
• what is the function of red blood fells in the blood?

  Oxygen transport
• what is the function of white blood cells in the blood?


  Immune defense (ingesting pathogens and producing antibodies)
• what is the function of platelets in the blood?


  Clotting blood