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BLOOD. - Dr. Padmini T. Specific Learning Objectives. At the end of the class, student should be able to: Describe composition & functions of blood Define Packed Cell Volume, factors affecting & methods of its determination.
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BLOOD - Dr. Padmini T.
Specific Learning Objectives • At the end of the class, student should be able to: • Describe composition & functions of blood • Define Packed Cell Volume, factors affecting & methods of its determination. • Describe plasma proteins – types, concentration, functions and variations.
Composition of blood • Total blood volume – 5- 6 litres • Specific gravity – 1.050-1.060 • pH – 7.4+ 0.05 , alkaline • Cells (45%) and plasma (55%)
Functions of blood 1. Respiratory 2. Nutritive 3. Excretory 4. Homeostatic 5. Regulation of body temperature 6. Role in immunity 7. Plasma protein functions
Packed Cell Volume • ‘ Haematocrit’ • Definition: Percentage of volume of the packed red cells following centrifugation. • Normal values: Male – 40% - 50% Female – 37%- 47%
Factors affecting PCV: Decrease in PCV • Physiological- • Pathological- Increase in PCV • Physiological- • Pathological-
Methods of determination of PCV • Manual method – Macrohaematocrit method ( Wintrobe’s method) • Automated method
Plasma Proteins • Normal total concentration – 6.4-8.3g/dLof blood • Types- Albumin (55%) Fibrinogen (7%) Globulin (38%)
Forms of plasma proteins • Prealbumin , albumin • Globulin- glycoprotein, lipoprotein, transferrin, haptoglobins, ceruloplasmins, coagulation factors, angiotensinogen, haemagglutinins, immunoglobulins.
FUNCTIONS 1. Helps in coagulation of blood 2. To maintain colloid osmotic pressure 3. Maintains viscosity of blood 4. Maintains systemic arterial pressure constant 5. Provides stability to blood 6. Maintains acid base balance in the body 7. Immune function 8. Transport function 9. Reservoir function
Variations 1. Decrease- infancy, newborn, pregnancy, haemorrhage 2. Increase- burns, dehydration, diabetes insipidus. 3. Decrease in albumin- pathological causes 4. Increase in gamma globulin – multiple myeloma, TB, cirrhosis etc. 5. Fibrinogen – decrease –DIC increase – malaria, pregnancy, infections