circulatory system 3 - blood

• name the 4 components of the blood

  • red blood cells
  • white blood cells
  • platelets
  • plasma
• what is blood plasma

  a yellow liquid within blood that transports substances around the body
• which substances are dissolved in the blood plasma

  • nutrients - glucose, amino acid, and glycerol
  • waste products - carbon dioxide and urea
  • other - antibodies and hormones
  • plasma also transports red blood cells, white blood cells, and platelets, but these are not dissolved in the plasma
• what is the role of red blood cells in blood

  to transport oxygen around the body
• how are red blood cels adapted to their function

  • contain haemoglobin - which binds to oxygen
  • biconcave shape - which increases the surface area to volume ratio
  • no nucleus - so can fit more haemoglobin in the cell
• what is the role of white blood cells in blood

  they form part of the immune system, which protects the body from invading pathogens, such as bacteria or viruses
• how are white blood cells adapted for their function

  • some can produces antibodies
  • some can produce antitoxins
  • some can engulf ad digest pathogens (‘phagocytosis’)
• what is the role of platelets in blood

  platelets are small call fragments (so have no nucleus), which help the blood to clot at the site of a wound
• give two reasons why blood clotting is important

  • it prevents blood from leaving the bloodstream
  • it prevents microorganisms from entering the bloodstream (which could cause infection)