Blood is a complex mixture of cells and liquid which is responsible for the transport of a range of substances around the body.
Blood is made up of a liquid called plasma which carries the red and white blood cells and platelets (involved in the clotting process).
Blood plasma is a yellow coloured liquid. The plasma transports the blood cells and a number of other substances around the body.
Small soluble products of digestion (e.g. glucose) move out of the gut and into the blood plasma. They are then carried by the plasma to the cells that need them.
Carbon Dioxide produced in respiration is carried by the blood plasma, The carbon dioxide diffuses into the blood plasma at the cells where it is produced and diffuses out of the plasma at the lungs.
Urea (formed from the breakdown of proteins) is another waste product carried by the plasma. It's removed from the plasma by the kidneys where it becomes part…