blood

• Why do red blood cells have a biconcave shape?


  give larger surface area to volume ratio for absorbing oxygen
• Why don't red blood cells have a nucleus?

  to create more room for carrying oxygen
• What do white blood cells do?

  fight infections by engulfing pathogens, producing antibodies and producing antitoxins to neutralise the toxins produced by bacteria
• What are the platelets and what do they do?

  small fragments of cells that have no nucleus. They help blood to clot around a wound to stop microorganisms from getting in
• What happens if you don't have platelets?

  excessive bleeding and bruising
• What is the plasma?

  liquid that carries soluble products of digestion in blood
• What are examples of what plasma carry?

  carbon dioxide, urea, hormones, proteins, red blood cells, white blood cells, platelets, antibodies, antitoxins
• What is the role of haemoglobin?

  for oxygen to bind to red blood cell
• 4 marker explain why and how a scab forms

  platelets arrive a site. fibrinogen form mesh over wound. red blood cells stick to mesh. clot form
• what are the risks of blood transfusions and what can be done to limit risk?


  infection. clotting. immune response. screen blood donated. test blood group of patient. use anti clotting drugs