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Blood plasma[edit | edit source]

Blood plasma is a yellowish, weakly basic solution of proteins, electrolytes, and small organic molecules. Its volume corresponds to 5%[1] of the body weight. It makes up approximately 55% of the blood volume and 25%[1] of the extracellular fluid volume. It is not only enclosed in the extracellular compartment but it is exchanged with intracellular fluid – 70% of the blood plasma is exchanged in one minute.[1]

Blood components

Basic parameters of blood plasma[1]

Parameter Value
Volume 2.8-3.5 liters
pH 7.4 ± 0.04
Osmolality 280–300 mosm/l
Osmotic pressure 5150 mmHg

Composition[edit | edit source]

Blood plasma consists of water (93%) and solutes. Dissolved substances in blood plasma can be divided into organic (6%) and inorganic (1%).[2]

Plasma - components

Inorganic substances[1][edit | edit source]

Substance Concentration Importance
Cations Sodium 136-148 mmol/l To maintain constant osmotic pressure, volume, and pH of the ECF.
Potassium 3.7-5.0 mmol/l For the excitability of nerves and muscles (mainly the myocardium); the main cation of ICF.
Calcium 2.15-2.61 mmol/l Occurs approximately one-half ionized (biologically active) and the other half non-ionized (bound to plasma proteins)

For neuromuscular transmission, contractility of the heart muscle, blood clotting. It affects the permeability of cell membranes.

Magnesium 0.66-0.94 mmol/l It has depressant effects on nervous excitement; for enzyme activity.
Iron men

Iron women

12–27 μmol/l

10–24 μmol/l

For the formation of Hb in the bone marrow; part of enzymes is involved in biological oxidation.
Copper 12–22 μmol/l Part of some enzymes; significance for hematopoiesis.
Anions Chlorides 95-110 mmol/l With Na+ osmolality maintaining,constant volume and pH ECF;

For the formation of HCl gastric juice.

Hydrogen carbonate


22-26 mmol/l For CO2 transport + part of the buffer system (buffers);

To maintain the pH of the ECF; volatile, easy to fade and easy to form.

Inorganic phosphorus 0.6-1.4 mmol/l Part of a buffer system (buffers); maintains the pH of the ECT.
Iodine 276–630 μmol/l For the production of thyroid hormones.

Organic substances[1][edit | edit source]

Proteins[edit | edit source]

For more information see the Plasma proteins page.

Total amount: 60-80 g/l

Category Protein Average

concentration (g/l)

Separately Prealbumin 0.3 Transport thyroxine and triiodothyronine, vit A
Albumin 42 Oncotic pressure; transport of MK, bilirubin, drugs; secondary carrier for heme, thyroxine, cortisol; reversible protein
Apolipoproteins (globulins) 4-9 Transport of triacylglycerols, phospholipids, cholesterol
Fibrinogen 4 Blood clotting
α-globulins Transcortin (α1-globulin) 0.04 Transport of cotrisol
Transcobalamin 94 x 10 -8 Vitamin B12 transport
α1-antitrypsin 2.5 Inhibition of proteinases (trypsin, chymotrypsin)
Metal-binding protein


0.055 Transport of barium, strontium, nickel
Antithrombin III (α2-globulin) 0.2 Thrombin inhibition
α2-macroglobulin 2.5 Plasmin and proteinase inhibition; carrier of certain cytokines and hormones
Haptoglobin (α2-globulin) 0.4-1.8 It binds Hb released during the intravascular breakdown of erythrocytes


0.35 Copper transport; ferroxidase enzyme
β-globulins Hemopexin (β1-globulin) 0.7 It binds heme (from Hb)
Transferrin (β1-globulin) 2.9 Iron transport
γ-globulins Immunoglobulins 15–16 Antibodies

Other[edit | edit source]

Substance Concentration
Glucose 3.3-6.1 mmol/l
Amino acids 2.3-3.9 mmol/l
Urea 3.0-7.6 mmol/l
Lipids (total lipemia) 4-9 g/l
Triacylglycerols 0.5-1.8 mmol/l
Phospholipids 1.8-2.5 g/l
Creatinine 55–110 μmol/l
Cholesterol (total) 3.5-5.2 mmol/l
Bilirubin 3.3-18.0 μmol/l
Lactate 0.55-2.22 mmol/l

Functions[edit | edit source]

  • Plasma volume maintenance;
  • transport functions;
  • isolation maintenance;
  • nutritional significance;
  • proteolytic systems;
  • plasma protease inhibitors;
  • defense of the organism against infection.

References[edit | edit source]

Related Articles[edit | edit source]

External links[edit | edit source]

References[edit | edit source]

  1. a b c d e f TROJAN, Stanislav – ET AL.,. Lékařská fyziologie. 4. edition. Grada, 2003. 112-113 pp. pp. 772. ISBN 80-247-0512-5.
  2. KITTNAR, Otomar. Lékařská fyziologie. 1. edition. Praha : Grada, 2011. 121 pp. pp. 790. ISBN 978-80-247-3068-4.

Sources[edit | edit source]

  • TROJAN, Stanislav – ET AL.,. Lékařská fyziologie. 4. edition. Grada, 2003. ISBN 80-247-0512-5.
  • KITTNAR, Otomar – ET AL.,. Lékařská fyziologie. 1. edition. Praha : Grada, 2011. pp. 790. ISBN 978-80-247-3068-4.

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