Blood makes up around 7% of the weight of a human body. Blood contains red blood cells, white blood cells and platelets. These blood cells float in a yellow liquid called blood plasma. Blood plasma is made up of 90% water and also contains various nutrients, electrolytes, gases, proteins, glucose and hormones. Blood plasma can be separated from the cells by spinning blood in a device known as a centrifuge until the cells collect at the bottom of the tube.

A blood donation occurs when a person voluntarily has blood drawn and used for transfusion. The Australian Red Cross blood service collects about a million blood donations a year. Most blood donors are unpaid volunteers who donate their blood for community supply.

Most of this blood is used for people who need treatment that require blood or blood products on a regular basis. Approximately 34% of donated red cells are used to help people with cancer and blood diseases. Donated blood is divided into separate components so that people can receive the most appropriate treatment. A process centrifuging does this by spinning the blood inside a centrifuge at very high speed. This separated the blood cells from the plasma; it is then stored, refrigerated until it is needed.

Blood is a specialized body fluid. It has four main components: plasma, red blood cells, white blood cells and platelets. Blood has many different functions: Transporting oxygen and nutrients to the lungs and tissues Forming blood clots to prevent excess blood loss Carrying cells and antibodies that fight infection Bringing waste products to the kidneys and liver, which filter and clean the blood Regulating body temperature

The blood that runs through the veins, arteries, and capillaries is known as whole blood, a mixture of about 55 percent plasma and 45 percent blood cells. About 7-8 percent of your total body weight is blood. An average sized man has about 5 litres of blood in his body.

Donated blood is used to make a variety of different products, including: Red cells- carry oxygen. Most recipients of donated blood are given red cells to boost the oxygen-carrying abilities of their own blood. Platelets- is needed for blood clotting. People who need extra platelets include those with certain diseases, such as leukaemia, or those recovering from severe blood haemorrhage White cells- makes up part of the immune system. A person with compromised immunity, perhaps following severe infection, may be given white cells to bolster their immune system

Plasma- is the liquid component of blood. Plasma helps boost blood volume. Cryoprecipitate- is found in plasma and contains clotting factors. Cryoprecipitate can be isolated from plasma and is commonly used to treat severe haemorrhage.

The plasma is also used for products such as: Immunoglobulin- to boost the immune system Anti-D- prevent haemolytic disease of the newborn Biostate (factor Vlll)- to treat haemophilia Human prothrombin- used to treat bleeding disorders Human albumin- to treat protein deficiency

Another valuable blood donation is cord blood donation. Cord blood is the blood that is left behind in the umbilical cord and placenta after a baby is born. Cord blood is rich in stem cells and these are the building blocks of all blood cells in our bodies. These cells are used to treat conditions such as: Immune deficiency Leukaemia Thalassaemia And some metabolic diseases

Artificial blood is a life-saving substance that carries oxygen to the body when there is a shortage of red blood cells. Artificial blood has properties that make it more practical to use especially in areas where refrigeration might not be an option, e.g. third world countries and war zones. In addition, artificial blood does not need to be specifically matched for type. While artificial blood does not perform all the functions of real blood, it carries out the necessary task of bringing oxygen to the cells. Two of the most common types of artificial blood are HBCOs (haemoglobin-based oxygen carriers) and PFCs (perflourocarbons).

BIBLIOGRAPHY Sydney Cord Blood Bank. (1995). Retrieved 11 22, 2012, from Sydney Cord Blood Bank: Corporate Communications, D. o. (2000). Better Health. Retrieved 11 22, 2012, from Better Health: Australian Red Cross Blood Servive. (1988). Retrieved 2012, from Australian Red Cross Blood Servive: American Society of Hematology. (2010). Retrieved 11 22, 2012, from American Society of Hematology: