BLOOD

 What is blood?

Blood is the special connective tissue. It cosist of a fluid matrix, plasma, formed element. Blood is the softest tissue in the body. Blood is slightly alkaline , having pH 7.4 . plasma is straw coloured ,viscous fluid consisting nearly 55% of the blood. Rest 45% are formed element .90-92% of plasma is water and 6-8% are protein . The proteins are- Fibrinogen, Globulin and Albumin. These proteins are synthesised in liver. 

Fibrinogen needs for clotting or coagulation of blood. Globulin involves in defense mechenism of the body. Albumin helps in osmotic balance. 

Plasma also contains small amount of minerals like Ca++,Na+, Mg++,HCO3-,Cl- etc. Glucose , amino acid, lipid etc also present in blood. 

Plasma without clotting factor is called serum.

Erythrocytes, leucocytes and platelets are collectively called formed element . They constitute nearly 45% of blood cell.

Blood= Plasma + RBC+ WBC+ platelets.

Erythrocytes or RBC are most abundant of all blood cell in the blood. A healthy man has on an average 5 -5.5 millions of RBCs mm-3 of blood. 

Leucocytes or WBCs are clourless due to lack of heamoglobin. They are nucleated and are lesser in number which are average 6000-8000mm-3 of blood.

Platelets also called thrombocytes . Blood normally contains 1,500,00-3,500,00 platelets mm-3. Platelets are involve in coagulating or clotting of blood. A reduction in their number can lead to clotting disorder.