Biochemistry of blood plasma

Organic constituents of blood plasma

Blood consists of 55%of plasma and 45% of cells (44% of erythrocytes and 1% of white blood cells).

Blood carries out the next functions:

1. trophic

2. respiratory

3. excretory

4. regulatory

5. preventive

Blood plasma consists of 90% of water and 10% of dry rest. Dry part of blood plasma is subdivided into 8-9% of organic constituents and 1-2% of inorganic constituents (cations and anions). Organic part of blood plasma consists of 6-8% of nitrogen-containing substances and 1-2% of nitrogenless substances (lipids, glucose and products of their metabolism).

Nitrogen-containing substances include 6-8% of proteins (60-80g/L of total protein) and 15-30mM/L of residual nitrogen (rest nitricum).

Total protein of blood plasma includes albumins (35-55g/L), globulins (25-30g/L) and fibrinogen (2-6g/L). If the content of proteins in blood serum to consider as 100%, so albumins make up 50-60%; globulins do 30-40%. Such percentage representation is characteristically for blood serum which differs from plasma of blood by absence of fibrinogen. Globulins have some fractions – alfa1 (0-5%), alfa2(5-10%), beta(10-15%) and gamma (15-20%).

Table 10 a main biochemical indices in the blood plasma (serum)

Index

Normal value

Proteins Total protein Albumins Globulins α1-globulins α2-globulins β-globulins γ-globulins Fibrinogen Residual nitrogen Urea Uric acid Uric acid Creatine Creatinine Total bilirubin Direct bilirubin Indirect bilirubin Compounds not containing nitrogen Glucose Lactic acid Pyruvic acid Total lipids TAG Total cholesterol Ketone bodies Inorganic compounds pH of art.blood Sodium Potassium Calcium Total phosphorus Inorganic phosphorus Chlorides

60-80g/L 35-55g/L 20-35g/L 0-5% 5-10% 10-15% 15-20% 2-6g/L 15-30mM/L 2.9-8.9mM/L 0.18-0.54mM/L (m) 0.15-0.45 mM/L (f) 50-70mcM/L 62-132 mcM/L 3.5-20.5mcM/L until 7mcM/L until 13mcM/L 3.3-6.0mM/L 0.44-1.8 mM/L 70-114mcM/L 4-7g/L 0.5-2.0mM/L 4.0-7.8mM/L (generally): until 20years old – 4.0-5.0 mM/L 20-30 – 4.0-6.0 mM/L 30-49 – 4.0-7.0mM/L after 50 – 4.0-7.8mM/L 0.2-0.6 mM/L 7.35-7.45 135-145 mM/L 2.5-5.0mM/L 2.1-2.75 mM/L 3.0-5.0mM/L 1.0-1.5mM/L 95-110mM/L

Proteins of blood plasma carry out the next functions:

1. maintenance of oncotic pressure (albumins)

2. maintenance of pH (in norm it is equal 7.35-7.44), i.e. proteins form buffer system: HxPr/NaxPr

3. coagulating and anticoagulating function

4. transport function, e.g. albumins transfer bilirubin, FFA, hormones, drugs; alfa-globulins transfer copper and lipids; beta-globulins transfer iron and cholesterol

5. prevent from infectious agents and other antigens (gamma-globulins)

There are hyper-, hypo-, dis- and paraproteinemia. Hyper- and hypoproteinemia can be absolute and relative. Absolute hyperproteinemia is associated with chronic inflammation and infections. Relative hyperproteinemia is associated with dehydration (serum deprivation). Absolute hypoproteinemia is associated with alimentary deficiency of proteins, infringement of digestion, absorption and metabolism of food proteins, neoplasm, deseases of liver and kidneys, increase of catabolism of tissue proteins, e.g. in burns, after operations, traumas. Relative hypoproteinemia is associated with hydration (increase of blood volume).

Paraproteinemia is associated with appearance of a new proteins, e.g. crioglobulins in some kinds of lymphopathies

Disproteinemia is shown in practictical lesson or see textbook on biochemistry.