Plasma is composed of 90% water and 10% dissolved solutes including proteins, electrolytes, nutrients, waste products, and gases. The major plasma proteins are albumin, globulins, fibrinogen, and prothrombin. Albumin is synthesized in the liver and maintains plasma colloidal pressure, while globulins are synthesized in the liver and lymphoid tissues and are involved in defense functions. Plasma proteins regulate osmotic pressure, act as a buffer, aid in blood clotting and viscosity, regulate capillary permeability, transport important substances, and provide amino acids to tissues. The ratio of albumin to globulins indicates liver function and inflammatory states.

1. Plasma
Water
90%
dissolved solutes
10%
blood gases
O2 and Co2
organic substancesIn-organic substances
9.1 %
0.9 %
Various
electrolytes
Plasma
Others
as Na+
proteins
2%
K+
7.1
Lipids, enzymes
Hco3Hormones,
Ca++
nutrients
Po4-Waste products

2. Plasma Proteins
Albumin
globulins
3.5 -5.0 gm%
2.5 – 3.5 gm%
0.3 gm%
0.01 gm%
Types
One type
Several types
One type
One type
M.W
69000
90000 - 156000
340000
Liver except
γ globulins
synthesized in
lymphoid tissues by
plasma cells
liver
Liver
Enzymatic function
Defense function
Blood clotting
Blood viscosity
Blood
clotting
%
Site of
liver
formation
Main
function
Maintaining
plasma colloidal.
Fibrinogen
Prothrombin

4. Dynamic state of plasma proteins
Plasma Proteins
Tissues
Amino acids
Plasma
Liver

5. When the level of plasma proteins decrease as in
:hemorrhage
:it can be regenerated in two phases
Slow phase
Rapid phase
( few hours )
)days(
from tissue proteins.
re-synthesis from
tissue proteins
and
dietary proteins

6. (Albumin / Globulin ratio (A / G
.It is the ratio between plasma levels of albumin and globulins
.The normal value for A/G ratio ranges from 1.2 – 1.6
A / G decreases in:
:Decrease plasma albumin level as in- 1
synthesis by the liver as in liver cirrhosis.
Intake as in malabsorption and mal nutrition
loss by the kidney as in nephrosis
Loss
loss by the skin in severe burns
.Increase plasma globulins level as in severe infections - 2

7. :A / G increases in
Congenital agammaglobulinemia where the
globulin fraction is decreased.

8. Functions of plasma proteins
1-Osmotic function.
2-Buffer function.
3-Defensive function.
4-Blood clotting.
5-Blood viscosity.
6-Regulation of capillary permeability.
7-Transport and conservation of important
elements.
8-Source of amino acids for the tissues

9. 1-Osmotic function.
Arterial end
Capillary B.P. 32 mm.Hg
Venous end
12 mm.Hg
Plasma proteins
No plasma proteins
Cells
Lymph

10. The osmotic pressure of the plasma = 5000 mmHg
Is due to
Crystalloids = Na, Cl, K …
Colloids = plasma proteins
.Crystalloids are present in the plasma and tissue fluid in the same concentration
And So
The net osmotic effect of crystalloids is zero
.The plasma proteins are present only in the plasma
The tissue fluid is almost free of proteins

11. .The plasma proteins are responsible for 25 – 30 mmHg of the plasma O.P
So, some fluid is reabsorbed from tissue fluid to the plasma by the
osmotic effect of plasma proteins.
Albumin is responsible for most ( 80 % ) of the osmotic pressure of the
:plasma due to
Highest concentration
Smallest molecular size = great number of molecules

12. 2-Buffer function:
Buffer system is composed of weak acid + its salt with a strong
base
): At normal Ph of blood ( 7.4, slightly alkaline
Plasma proteins are present in the form of proteinic acid ( weak
acid ) and Na proteinate ( its salt with strong base).
Thus it acts as a buffer system preventing
. excessive changes in Ph
Lactic acid (relatively strong) + Na protinate
proteinic acid ( weak acid )
NaOH (strong alkali) + proteinic acid
Na lactate +
Na proteinate + H2O

13. 3-Defensive function.
Gamma globulins are responsible for
defending the body against micro-organisms
and their toxins {humoral immunity}.

14. 4-Blood clotting.
Fibrinogen, prothrombin and other protein clotting factors
are essential for the coagulation process.

15. 5-Blood viscosity.
Blood
3.0
1.5
1.0
plasma
Water

16. Viscosity is important in the production of the peripheral
resistance and maintenance of arterial blood pressure.
The fibrinogen molecule contributes more than other
plasma proteins to the viscosity of the blood because of its
.elongated shape
RBC’s are the main cause of blood viscosity because it
is the main cellular element of the blood

17. 6-Regulation of capillary permeability
Most of the pores in the capillary wall are closed by
.plasma proteins
Decrease plasma proteins is associated with increasing
Capillary permeability.

18. 7-Transport and conservation of important
elements.
carriers for important substances as hormones**
Significance:
The combined form acts as reservoir from which the free
substance is slowly releases e.g. Free T3
Prevent filtration of substances in the kidney and their
loss in urine.
**Bind harmful substances to prevent their hazards
e.g. bilirubin.

19. 8- Plasma proteins as a source of amino acids for
the tissues
Plasma proteins act as a source for
rapid replacement of tissue proteins
in case of tissue protein depletion.