Blood and Blood Components

Normally, 7-8% of human body weight is from blood.  

In adults, this amounts to 4.5-6 quarts of blood.  

This essential fluid carries out the critical functions of transporting oxygen and nutrients to our cells and getting rid of carbon dioxide, ammonia, and other waste products.  

In addition, it plays a vital role in our immune system and in maintaining a relatively constant body temperature.  

Blood is a highly specialized tissue composed of more than 4,000 different kinds of components.  

The components of human blood are:

•  Red blood cells (erythrocytes). These carry oxygen from the lungs to the rest of the     body
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•  White blood cells (leukocytes). These help fight infections and aid in the   immune process. Types of white blood cells include:

1.  Lymphocytes
2.  Monocytes
3.  Eosinophils
4.  Basophils
5.  Neutrophils

         Plasma. The liquid component of the blood in which the following blood cells are suspended:

        Platelets (Thrombocytes). These help in blood clotting.

Components Separating in Blood Bank:

The whole blood which is a mixture of cells, colloids and crystalloids can be separated into different blood components namely 

• Packed Red Blood Cell (PRBC) concentrate, 
• Platelet Concentrate, 
• Fresh Frozen Plasma,
• Cryoprecipitate. 

Each blood component is used for a different indication; thus the component separation has maximized the utility of one whole blood unit. 

Different components need different storage conditions and temperature requirements for therapeutic efficacy. 

A variety of equipment to maintain suitable ambient conditions during storage and transportation are in vogue. 

The blood components being foreign to a patient may produce adverse effects that may range from mild allergic manifestations to fatal reactions. Such reactions are usually caused by plasma proteins, leukocytes, red cell antigens, plasma and other pathogens. 

To avoid and reduce such complications, blood products are modified as leukoreduced products, irradiated products, volume reduced products, saline washed products and pathogen inactivated products. 

The maintenance of blood inventory forms a major concern of blood banking particularly of rare blood groups routinely and common blood groups during disasters. PRBCs can be stored for years using cryopreservation techniques. New researches in red cell cultures and blood substitutes herald new era in blood banking.