Bloodis crucial for transportation of nutrients and gases from an external

environment to cells, plus, transporting wastes from cells to be excreted from the body

By Kirsten Cluett

Composition of Blood

If a mammal’s blood was sampled and spun in a centrifuge…

• The blood would split into cellular matter and plasma

• Plasma making up 55% by volume

• Cell fraction making up 45%- Consisting of red and white blood cells and platelets

Components - Plasma

• Sticky, off-white slightly salty liquid• (Suspends) Red and White Blood cells

and platelets• Transports nutrients, and other

substances e.g. Carbon Dioxide waste• Contain substances that stabilise pH and

osmotic pressure• Substances in plasma clot blood when

needed act in immune response

Components – Cellular MatterRED BLOOD CELL: (erythrocytes)• Biconcave, disc-shaped• In humans have no nuclei• Remain in the blood for 3 months• Contain haemoglobin (oxy-haemoglobin transporting oxygen) and other respiratory

gases are transported• 1mL = 5-6 million in blood

WHITE BLOOD CELL: (leucocytes)• Contain a nucleus• Larger than red blood cells• Phagocytes – collects at areas of infection, ingesting foreign bodies. Lymphocytes – act

against foreign material, and make antibodies to fight against disease • Important in immune response• 1mL = 4000-12000 in blood

PLATELETS:• Makes up a tiny <0.01% part in one blood part• Helps the blood to clot• Aids in inflammation

Blood Composition - Centrifuged

Donated Blood• Usually 450 mL given each

donation• Donors are screened and

regulated• Checked to prevent antibodies

in donation do not react with patient’s red cell antigens

Packaged into products:• Whole blood• Packaged red blood cells• Plasma• Platelet concentrate• Cryopreciptated AHF• Plasma fractions

Donated BloodExtracted Parts

Various components of blood can be separated from whole blood to help a patient’s specific needs

• Red Blood Cells: Increase oxygen carried to body’s tissues.Given to people with… anaemia, blood loss patients and patients with bone marrow red blood cell deficiency

• Platelets: Are essential for blood clottingFor cancer of the blood, Leukaemia (Cancer patients often don’t make enough blood platelets)

• Plasma: Blood-clotting factors, adjusts osmotic pressure of bloodFor people with clotting disorders like Haemophilia. Adjusts osmotic pressure of blood

• Immunoglobins: Antibodies. Infection-fighting part of blood plasma For people with difficulty fighting infections and immune system malfunction e.g. AIDS.

• Clotting factors 8 and 11 • Granulocytes

How are These Parts Separated?

Packaged red blood cells: • Extracted from whole blood by removing liquid plasma. • The blood is centrifuged and red blood cells will fall the

bottom, the heaviest particle• Suitable for sufferers of kidney failure and chronic

anaemia

Cryoprecipitated AHF: • To be removed from plasma, it is frozen then thawed• Controls or prevents bleeding – suitable for people with

haemophilia

Continued.• Blood processing allows blood parts to be separated from each other. There are different methods to achieve this

• A hematocrit tube holds blood and is placed in a centrifuge - causing components to split and red blood cells falling to the bottom of the tube

• Blood component therapy allows an extracted component of the blood (e.g. plasma) to be given to a patient by method of blood transfusion (here the same blood type must be donated)

• Blood component therapy allows specific blood components to be brought together for a patient’s needs

Uses of Extracted Parts of BloodRed blood cells• Majority to people with cancer• Traumatic accidents (with dramatic blood loss) • Burns victims or surgery patientsPlasma• Trauma, burns and blood disease• Makes up 17 life-saving productsPlatelets• People with low platelet count• Bleeding or risk of bleeding patients with non-functioning platelets• Cancer patients (chemotherapy)• Bone marrow transplant• Liver disease• Major trauma• Surgery patients

Red Cross Blood Service

Artificial Blood

• Used when a patient suffers large volumes of blood loss

• Carry oxygen and carbon dioxide• Do not clot blood or involved in immune

defence• Substitute for plasma to maintain blood

pressure (but do not supply oxygen to tissues)• Two types of oxygen carriers: haemoglobin-

based and Perfluerochemicals

Artificial blood fluids: • Normal saline (same concentration as blood

0.9%)• Dextrose 4% in a 0.18% saline solution

Need for Artificial Blood• Advantageous: Free of infectious agents, non-toxic and disease free which

is important in countries where blood transfusions contain diseases e.g. Nigeria has AIDS spreading in blood transfusions

• Universal acceptance• Stored at room temperature• Available in large supplies• PFC-based artificial blood can be used temporarily during open heart

surgery – minimises blood loss during operation• Transfusion without any tests required (blood type does not need to be

matched and antigens will not interfere)• Can be kept for long periods of time (2-3 years) compared to human blood’s

3 weeks• Rapid treatment in trauma patients• Oxygen carrying blood substitutes can be used for religious/cultural

objectors of blood transfusions • Currently cost-effective• Useful in surgery, trauma and oxygenation of tumours during chemotherapy

Bibliography• Hill, J. and Alford, D. (2004). Excel

HSC Biology. New South Wales: Pascal Press

• Humphreys, K. (2004). Surfing. New South Wales: Science Press

• Mudie, K. and brotherton, J. (2004). Heinemann Biology. Victoria: Reed International Books Australia Pty Ltd

• ‘How donated blood is used’ http://www.donateblood.com.au/why-donate/blood-use (24 Nov 2012)