What is blood?
Blood contains red and white blood cells that float inside a liquid called plasma. It also contains thousands of different substances needed by the body. Blood carries all these things around the body and also removes waste products. It is part of the body’s communication system, carrying chemical messengers called hormones that switch organs on and off as required.
Blood carries the white cells and chemical substances that attack invading bacteria and viruses. It also helps control body temperature. Red blood cells carry oxygen collected from the lungs to all parts of the body, releasing it where required. White bloods cells help protect the body from infection. They can produce disease-fighting substances called antibodies.
What are blood groups?
A blood group is a particular type of blood that may not match with other blood types when given in a blood transfusion. Blood groups differ from person to person. There are four main blood groups: O, A, B and AB. These letters refer to chemicals on the surface of red blood cells that are recognized by the body’s defences. When a person receives a blood transfusion, the blood groups need to be carefully matched to make sure that they are compatible.
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