Blood Plasma
Plasma is a pale yellowish fluid with a total volume of 2-3 liters in a normal adult.

Its contents are :

Water 90.0%
Protein 8.0%
Inorganic Ions 0.9%
Organic Substances 1.1%
 

Plasma Proteins
Plasma proteins are made up of 3 main types.

  • Serum Albumin
  • Serum Globulin
  • Fibrinogen
  • Prothrombin

Most of the proteins are produced by the liver apart from the Serum Globulin which is produced by the body's immune system. Serum Albumin composed of 60% of the total plasma protein. It is the smallest of the 4 plasma proteins and can pass through capillary walls. Hence this will usually lead to a small leakage into the intestinal fluid. Nonetheless, this has been exploited by medical science to be an effective medium of testing for abnormalities in the body and damaged organs or diseases. Serum Globulins make up 36% of the total plasma protein. This can be further split into 3 fragments, the alpha, beta and gamma. Globulins aid in the inflammatory response of the body. Fibrinogen and prothrombin are important in the clotting process of blood.

Protein Functions Include:

  • Transportation of insoluble substances around the body by allowing them to bind to protein molecules.
  • Protein reserve for the body
  • Blood clotting
  • Responses in accordance to disease (inflammatory response)
  • Protection from infection the gamma globulins function
  • Striking balance for the pH of the blood

Inorganic Ions
Inorganic ions play a very important role in the blood.

ION SYMBOL CONCENTRATION (mmol/l)
Sodium Na+ 135-146
Potassium K+ 3.5-5.2
Calcium Ca++ 2.1-2.7
Chloride Cl- 98-108
Hydrogen Carbonate HCO3- 23-31
Phosphate PO4-- 0.7-1.4

Without sodium, the body will lack extracellular fluid and might affect the blood pressure, leading to insufficient circulation of oxygen causing drowsiness, nausea etc. Lack of potassium will result in muscle abnormalities and weakness, leading to vomiting and diarrhea. Hence all the inorganic ions facilitate in a very important role as do other cells within the blood.

Organic Substances
Blood plasma carry organic substances such as nutrients. They may include digested food substances like glucose, sucrose and amino acids. Other nutrients in transit in the plasma include glycerol, triglycerides, cholesterol and vitamins. Waste products of the body are also transmitted in the blood plasma. They include urea and cellular waste that will be excreted out of the body. Hormones, such as cortisol and thyroxine are also transported around the body in plasma attached to plasma proteins. Medicine and drugs also circulate within the plasma.

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