• Red blood cells are?specialised cells?which carry?oxygen to respiring cells
• They are adapted for this function in 3 key ways
  • They are full of?haemoglobin, a protein that binds to oxygen to form oxyhaemoglobin
  • They have?no nucleus?which allows more space for haemoglobin to be packed in
  • The shape of a red blood cell is described as being a?'biconcave disk'??this shape gives them a?large surface area to volume ratio?to maximise diffusion of oxygen in and out

   

Red blood cells

• Plasma?is a straw coloured liquid which the other components of the blood are suspended within
• Plasma is important for the transport of many substances including:
  • Carbon dioxide -?the waste product of?respiration,?dissolved in the plasma as hydrogencarbonate ions and transported from?respiring cells?to the?lungs
  • Digested food and mineral ions -?dissolved particles absorbed from the small intestine and delivered to?requiring cells?around the body
  • Urea?- the waste substance produced in the?breakdown of proteins?by the liver. Urea is dissolved in the plasma and transported to the?kidneys
  • Hormones - chemical messengers?released into the blood from the endocrine organs (glands) and delivered to?target tissues/organs of the body
  • Heat energy -?created in?respiration?(an exothermic reaction), heat energy is transferred to?cooler parts?of the body or to the?skin?where heat can be lost

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