PLASMA PROTEIN Flashcards
Plasma Protein
❖Major solid constituent of the plasma
❖Total plasma protein concentration is
7.4 g/dL (6.4 - 8.3 g/dL)
types of plasma protein
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Albumin features
- Plasma levels are 4.8 g/dL (range 3–5 g/dL)
- Molecular weight of prealbumin is 60,000 and of albumin is 69,000
- Synthesis - Liver
Globulin
- Plasma levels are 2.3 g/dL (range 2 to 3 g/dL).
- Molecular weight varies from 90,000 to 156,000.
- Types include α1, α2, β1, β2 and γ globulins.
Fibrinogen
- Plasma levels are 0.3 g/dL.
- Molecular weight is 500,000.
- Synthesized in the liver.
Synthesis of Plasma Proteins
embryo- mesenchymal cells
adult- ❖Albumin and fibrinogen - RES (reticuloendothelial system) of liver
❖α & β globulins- liver, spleen and bone
marrow
❖γ globulins- B lymphocytes
Functions of Plasma Proteins (11)
Exert Osmotic Pressure
Blood coagulation
Maintain acid-base balance
Role as preserve protein
Fibrinolytic function
Nourishment of tissue cells
Contribution to blood viscosity
Defense mechanism
Transport function
Role in suspension stability of RBCs
Role ingenetic information
Exert Osmotic Pressure
-Protein molecules unable to pass caused exert colloid osmotic pressure
❖ Pressure - Important in exchange of water between the blood and tissue fluid
Contribution to blood viscosity
❖ Fibrinogen and globulins are significant contributors
❖ The blood viscosity plays an important role in the maintenance of blood pressure→resistance to flow of blood in blood vessels
Blood coagulation
❖ The fibrinogen, prothrombin and other coagulation proteins present in the plasma play an important role in the coagulation of blood.
Defense mechanism
❖ The γ globulins – antibodies which play an important role in the immune system – against the microorganisms.
Maintain acid-base balance
❖ Plasma proteins act as buffers and contribute for about 15% of the buffering capacity of blood.
Transport function
❖ Plasma proteins combine easily with many substances and play an essential role in their transport as i.e. carbon dioxide, thyroxine, cortisol, vitamin A, D and Vitamin B12, bilirubin, drugs, calcium & copper
Role as preserve protein
❖ Plasma proteins serve as reserve proteins and are utilized by the body tissues during conditions like: Fasting, inadequate protein intake and excessive catabolism of body proteins
Role in suspension stability of RBCs
❖ Property of RBCs - remain uniformly suspended in the blood. Globulins and fibrinogen accelerate this property
Fibrinolytic function
❖ The enzymes of the fibrinolytic system digest the blood clot (thrombus)
Role in genetic information
❖ Many plasma proteins exhibit polymorphism. Polymorphism is a Mendelian trait that exists in the population with differing prevalence.
Nourishment of tissue cells
❖ The plasma proteins are utilized by the leucocytes to produce the substances known as trephones or carrel – nourishment of tissue cells
Changes of Plasma Protein in Health & Diseases
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DESCRIBE Physiological Variations
Infant
The total protein level is low (about 5.5 g/dL) due to low γ globulins.
Old age
There is a tendency for the albumin level to fall and the total globulin level to rise.
Pregnancy
During first 6 months, the albumin and globulin levels decrease while the fibrinogen level increases.
DESCRIBE Abnormalities of Plasma Protein
Hypo-proteinaemia
Decrease in the levels of plasma proteins.
Hyper-proteinaemia
Increase in the levels of plasma proteins.
Reversal of normal A/G ratio
* The (A/G) ratio (1.7:1) is reversed in the following conditions:
i. When the albumin synthesis is decreased
ii. When the globulin levels are increased
There is pressure between blood vessel and
ECF
Why??
Differences in pressure in the blood pressure and osmotic pressure helps fluids move out of capillaries at the arterial end and into capillaries at the venous end
There is pressure between blood vessel and
ECF
Why??
Differences in pressure in the blood pressure and osmotic pressure helps fluids move out of capillaries at the arterial end and into capillaries at the venous end
Capillary Fluid Exchange
-When capillary pressure increases, fluid is filtered into the interstitial fluid due to hydrostatic force
-When capillary pressure decreases, fluid is absorbed into the capillary due to oncotic pressure
So, what is the role of plasma proteins in starling force
Starling’s forces
Forces that control the movement of fluid in/out of a capillary
Hydrostatic Pressure, P
Pressure exerted by blood (water) on the walls of blood vessel
-13 mmHg filtration pressure
Colloid osmotic (oncotic) Pressure, π
-Pressure created by non-diffusible plasma protein inside the blood vessel
-7 mmHg
-hyperprotein- higher pressure
- hypoprotein- low pressure
The Lymphatic System
❖ The lymphatic system – which fluid can flow from the interstitial spaces into the blood.
❖ can carry proteins and large particulate matter away from the tissue spaces
❖ This return of proteins to the blood from the interstitial spaces is an essential function without which we would die within about 24 hours
Importance of The Lymphatic System
control:
-The concentration of proteins in the interstitial fluids
-The volume of interstitial fluid
-The interstitial fluid pressure
Negative pressure
cause edema- Atypical accumulation of fluid in the interstitial space, leading to tissue swelling
