C HAPTER . Blood . Lymph (Tissue Fluid) . Circulatory Pathways .
Double Circulation . Regulation of Cardiac Activity . Disorders of Circulatory System Fibrinogens are needed for clotting or coagulation of blood. Globulins primarly are involved in defense mechanisms of the body and the albumins help in osmotic balance.
Plasma also contains small amounts of minerals like Na + , Ca ++ , Mg ++ , HCO – , Cl – , etc. Glucose, amino acids, lipids, etc., are also present in the plasma as they are always in transit in the body. Factors for coagulation or clotting of blood are also present in the plasma in an inactive form. Plasma without the clotting factors is called serum.
. . Formed Elements Erythrocytes, leucocytes and platelets are collectively called formed elements (Figure . ) and they constitute nearly per cent of the blood.
Erythrocytes or red blood cells (RBC) are the most abundant of all the cells in blood. A healthy adult man has, on an average, millions to . millions of RBCs mm – of blood. RBCs are formed in the red bone marrow in the adults.
RBCs are devoid of nucleus in most of the mammals and are biconcave in shape. They have a red coloured, iron containing complex protein called haemoglobin, hence the colour and name of these cells. A healthy individual has - gms of haemoglobin in every ml of blood. These molecules play a significant role in transport of respiratory gases.
RBCs have an average life span of days after which they are destroyed in the spleen (graveyard of RBCs). Leucocytes are also known as white blood cells (WBC) as they are colourless due to the lack of haemoglobin. They are nucleated and are relatively lesser in number which averages - mm – of blood. Leucocytes are generally short lived.
We have two main categories of WBCs – granulocytes and agranulocytes. Neutrophils, eosinophils and basophils are different types of granulocytes, while lymphocytes and monocytes are the agranulocytes. Neutrophils are the most abundant cells ( - per cent) of the total