BLOOD By: Sathish Rajamani Associate Professor

INTRODUCTION Blood is a connective tissue in fluid form. It is considered as the ‘Fluid of Life’, ‘fluid of growth’ and ‘fluid of health’

Properties of Blood Color: Red, Arteria Blood is Scarlet red and Venous Blood is Purple red. Volume: Average Volume is 5 L in normal adult. In newborn it is 450 ml. in female it is 4.5L. Reaction and pH: Slightly alkaline (ph value is 7.4) Viscosity: More Viscous than water Specific Gravity: Total blood cells – to Blood Cells:1.092 – to Plasma: to 1.026

Blood Cells There are 3 types of blood cells 1. Red Blood Cells or Erythrocytes White Blood Cells or Leukocytes Platelets or Thrombocytes

Hematocrit Volume Volume of red blood cells expressed in percentage is called as Hematocrit Volume, or Packed Cell Volume. If a blood is collected in a hematocrit tube along with a suitable anti coagulant and centrifuged for 30 minutes at a speed of 3000 revolutions per minute, the red blood cells settle down at the bottom having a clear plasma at the top. Plasma forms 55% and red blood cells forms 45 % of the total blood. In between plasma and red blood cells, there is a thin layer of White Buffy Coat. This is formed due to the aggregation of WBC and Platelets.

Plasma and Serum Plasma is a straw colored clear liquid part of blood. It contains 91 to 92 % of water and 8 to 9 % of solids. Serum is a straw colored fluid that oozes from the blood clot. When the blood is shed or collected in a container, it clots, in this process, the fibrinogen is converted into fibrin and the blood cells are trapped in this fibrin forming the blood clot. After about 45 minutes, serum oozes out of the blood clot. Serum = Plasma minus Fibrinogen

FUNCTIONS OF BLOOD Nutritive Function Respiratory Function Excretory Function Transport of Hormones & Enzymes Regulation of Water Balance Regulation of Acid – Base Balance Regulation of Body Temperature Storage Function Defenseive Function