Download FUNCTIONS OF PLASMA PROTEINS

FUNCTIONS OF PLASMA
PROTEINS
Dr. B. L. Mtinangi
Department of Physiology
University of Dar es Salaam
November, 2015
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PLASMA
Is an extracellular fluid in the
INTRAVASCULAR compartment
 A straw coloured fluid at the top after
centrifugation of uncoagulated blood
 Contain 7% protein
 Normal total plasma protein is about 77.5g/dl and Albumin is about 4.8gm%,
Globulin-2.3gm%, Fibrinogen- 0.3gm%
& Protrombin 0.03gm%

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PLASMA COMPOSITION
Water is about 91% to 92%
 Inorganic substances Na+, Ca2+
Cl-,K+ etc
 Organic substances like Amino
acids ( AA), Glucose, Free Fatty
Acids etc
 Internal secretion like hormones,
enzymes, antibodies etc

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SERUM
Serum is a clear fluid from the
clotted blood ie Plasma without
some clotting factors or
 A clear fluid at the top after
centrifugation of coagulated blood

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SOME SPECIFIC FUNCTIONS
OF PLASMA PROTEINS
Maintainance of Colloid Osmotic
Pressure ie Plasma Colloid Osmotic
Pressure especially albumin (PCOP)
 Maintainance of PH and electrolytes
balance
 Transport of metal ions e.g copper, iron
etc.
 Transport of fatty acids, Steroids,
hormones & drugs

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COMPOSITION OF PLASMA
PROTEIN
Plasma protein is mainly composed
of:
 Albumin
for Plasma colloidal
osmotic pressure (PCOP)
 Fibrinogen and other clotting
factors like prothrombin etc
 Globulins: subtypes alpha1 &
2, beta 1 & 2, and gamma
globulins for body immunity
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METHODS OF PLASMA
PROTEIN SEPARATION
COMMON METHODS of protein
separation into albumin,
fibrinogen, alpha, beta and
gamma globulins
 Paper electrophoresis
 Ultracentrifugation
 Affinity chromatography
 Fractional precipitation method
 Immune electrophoresis
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SEPARATION CONT.
For example Electrophoresis
separation pattern depends on:
 Size
 Shape
 Composition
 Physiological function of each
plasma protein
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SPECIFIC PLASMA PROTEIN
Plasma Albumin.
 Forms 60% total plasma proteins
 Normal value 3.4 to 4.5g/dl
 Responsible for 80% PCOP
 Acts as a carrier of e.g bilirubin
and drugs
 Synthetized in the liver
 Molecular Weight (MW). 69000
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PLASMA GLOBULINS
Plasma Globulins stands for alpha1,
alpha2, beta and gammaglobulins.
 alpha1 globulins is a glycoprotein
which binds two thirds of glucose.
 Alpha2 globulins consists of
haptoglobin which binds free
haemoglobin and ceruloplasmin
which binds copper
 Beta globulins has MW 90,000
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GLOBULINS CONT.
beta globulins is a lipoprotein a
protein that carries LIPIDS (75%)
and polysaccharides.
It also binds and transport IRON
 gamma globulins (MW 156,000) it
is for IMMUNOGLOBULINS
(antibodies ) ie it is responsible
for body protection and defence

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FIBRINOGEN
Fibrinogen:
 Is a plasma clotting factor
 Manufactured in the liver
 Normal value is 4% to 6%
of total plasma protein
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SUMMARY OF PLASMA PROTEINS
Exerts Colloid Osmotic Pressure
 Viscosity of blood ie 50% is due to
plasma proteins and 50% due to
Rbcs
 Role in coagulation of blood
 Acts as buffers ie contribute 15%
of the buffering power of blood
 Transport function ie Oxygen
combines with haemoglobin & CO2
combines with plasma proteins
 Defence function eg gamma

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Thank you