Blood is essential for life! It delivers necessary substances such as nutrients and oxygen to the cells as well as transporting metabolic waste products away from the cells. It is made up of blood cells suspended in blood plasma. Plasma is mostly water but it also contains proteins, glucose, mineral ions, hormones, carbon dioxide and blood cells. The blood cells are mainly red blood cells, white blood cells and platelets. The red blood cells contain haemoglobin. This is an iron-containing protein which transports oxygen to the organs. Without enough blood the body cannot function.