Blood and lymph are special types of fluid connective tissues derived from mesoderm.
Blood transports respiratory gases, waste products, hormones and enzymes.
Blood constitutes about 8% of the total body weight; blood volume is 5-6 litres in man and 4-5 litres in female.
pH of blood is 7.4 (slightly alkaline), pH of blood in arteries is more than in veins and is maintained by balancing the ratio of sodium bicarbonate and carbonic acid. Sodium bicarbonate is called the buffer of the blood.
With increase in acidity of blood, the efficiency of hemoglobin decreases and it carries less oxygen.
The blood is composed of a pale yellow transparent fluid known as plasma and contains floating cells or corpuscles. The plasma constitutes 55% and corpuscles 45% of the volume of blood.
Hematocrit value of blood is the index of the percentage of blood occupied by RBC’s. It is important in diagnosing the cases of anaemia or polycythemia.
Plasma is composed of 90-92% water and 8% of plasma proteins. Major plasma proteins are albumin, globulin, immunoglobulin, prothrombin and fibrinogen.
Albumin maintains normal blood pressure and helps in osmo-regulation in cells and tissue fluids.
Immunoglobulins (Ig) act as antibodies and help to develop immunity in the body.
Prothrombin and fibrinogen are essential for blood clotting.
