What is the function of Plasma protein?

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Plasma is present in the blood and constitutes the liquid part of the blood. It is made up of 90% water which is required for hydration of body tissues. 7% of plasma is composed of proteins and looks like a pale yellow liquid. Blood plasma is made up of approximately 20% of extracellular body fluid and the composition is almost similar to interstitial fluid. The major difference between the two fluids is the presence of protein content. Interstial fluid comprise of only 2% of protein because the plasma protein molecules are way too large and hence cannot penetrate through the capillary walls located in the interstitial area. And when protein does leak in small volume, the lymph takes it up and returns it back to the blood.

What are the different types of plasma proteins?

There are three main groups of plasma protein:

  • Albumin: It comprises of 60% of overall plasma protein and hence Albumins are the highly abundant plasma proteins. These are produced by the liver and helps in transportation of different components in blood, along with drugs. Albumins also help to maintain water balance in the body and  contribute to osmotic pressure.
  • Globulin: These comprise of 36% of overall plasma protein and include protein carriers, enzymes, gamma globulin and antibodies. Globulins are fractionized into alpha, beta and gamma and although all the globulins are manufactured in liver, gamma globulins are especially produced by lymphocytes also termed as plasma cells.
  • Fibrinogen: These comprise of merely 4% of overall plasma protein and are also called as Factor I. This plasma protein is also created by liver and its only function is to make clots and stop bleeding. It is very sticky and is a fibrous coagulant present in blood which produces thrombin. This thrombin then gets transformed into fibrin which is the major protein in blood clot.

 

What are the disorders caused by fibrinogen deficiency?

Hemophilia or bleeding disease is caused due to the deficiency of Factor I and can be hereditary problem. Absence of fibrinogen plasma protein causes a serious disease called as fibrinogenemia . Hypofibrigenemia is although a lower form of hemophilia, it also produces medium bleeding problems. Many times the fibrinogen levels are normal but the functioning of protein is normal. Such a condition is called as Dysfibrinogenemia. People with such disorders never have problem clotting; rather they have been found to clot abnormally.

What are the functions of plasma protein?

The functions of plasma proteins include:

  • Osmotic or intravascular effect of plasma protein maintains fluid as well as electrolyte balance
  • Viscosity of plasma is maintained by the plasma protein
  • These are the protein reserves of our body
  • Performs the important function of clotting
  • Responds with inflammation in case of wound or injury
  • The gamma globulins act as antibodies and protect our body from infection
  • Plasma protein also maintains acid base balance

 

What are the disorders associated with plasma protein?

Decrease in albumin percentage in plasma protein is an indication of kidney or liver disease. In these diseases the albumin enters the urine. High albumin levels are the indication of dehydration or congestive heart failure. Liver disease, chronic infection or rheumatoid arthritis is also indicated by the increase in the level of globulin levels. Low level globulin presence indicates liver dysfunction, anemia or even emphysema. When the fibrinogens level increases, it is an indication of increase in stroke risk, and if the patient also has blood pressure, the risk is even more. The fibrinogen levels are maintained by regular exercise, quitting smoking, maintaining ideal weight and taking proper medication.

 

How does protein binding help in drug action?

Recent studies have revealed that extensive plasma protein binding increases the measure of drug to be absorbed, even before the therapeutic drug levels are reached. For example, acidic drugs like aspirin more often than not have been found to get substantially bounded to albumin.

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