Download blood - Yengage

BLOOD
- Dr. Padmini T.
Specific Learning Objectives
 At the end of the class, student should
be able to:
1. Describe composition & functions of
blood
2. Define Packed Cell Volume, factors
affecting & methods of its determination.
3. 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
1. Physiological2. PathologicalIncrease in PCV
1. Physiological2. 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
TypesAlbumin (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